All but two of the callers already have a folio; pass a folio into
try_to_free_buffers(). This removes the last user of cancel_dirty_page()
so remove that wrapper function too.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
swap_writepage() is given one page at a time, but may be called repeatedly
in succession.
For block-device swapspace, the blk_plug functionality allows the multiple
pages to be combined together at lower layers. That cannot be used for
SWP_FS_OPS as blk_plug may not exist - it is only active when
CONFIG_BLOCK=y. Consequently all swap reads over NFS are single page
reads.
With this patch we pass a pointer-to-pointer via the wbc. swap_writepage
can store state between calls - much like the pointer passed explicitly to
swap_readpage. After calling swap_writepage() some number of times, the
state will be passed to swap_write_unplug() which can submit the combined
request.
Link: https://lkml.kernel.org/r/164859778128.29473.5191868522654408537.stgit@noble.brown
Signed-off-by: NeilBrown <neilb@suse.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Tested-by: David Howells <dhowells@redhat.com>
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Hugh Dickins <hughd@google.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Trond Myklebust <trond.myklebust@hammerspace.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
If swap-out is using filesystem operations (SWP_FS_OPS), then it is not
safe to enter the FS for reclaim. So only down-grade the requirement for
swap pages to __GFP_IO after checking that SWP_FS_OPS are not being used.
This makes the calculation of "may_enter_fs" slightly more complex, so
move it into a separate function. with that done, there is little value
in maintaining the bool variable any more. So replace the may_enter_fs
variable with a may_enter_fs() function. This removes any risk for the
variable becoming out-of-date.
Link: https://lkml.kernel.org/r/164859778124.29473.16176717935781721855.stgit@noble.brown
Signed-off-by: NeilBrown <neilb@suse.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Tested-by: David Howells <dhowells@redhat.com>
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Hugh Dickins <hughd@google.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Trond Myklebust <trond.myklebust@hammerspace.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "MM changes to improve swap-over-NFS support".
Assorted improvements for swap-via-filesystem.
This is a resend of these patches, rebased on current HEAD. The only
substantial changes is that swap_dirty_folio has replaced
swap_set_page_dirty.
Currently swap-via-fs (SWP_FS_OPS) doesn't work for any filesystem. It
has previously worked for NFS but that broke a few releases back. This
series changes to use a new ->swap_rw rather than ->readpage and
->direct_IO. It also makes other improvements.
There is a companion series already in linux-next which fixes various
issues with NFS. Once both series land, a final patch is needed which
changes NFS over to use ->swap_rw.
This patch (of 10):
Many functions declared in include/linux/swap.h are only used within mm/
Create a new "mm/swap.h" and move some of these declarations there.
Remove the redundant 'extern' from the function declarations.
[akpm@linux-foundation.org: mm/memory-failure.c needs mm/swap.h]
Link: https://lkml.kernel.org/r/164859751830.29473.5309689752169286816.stgit@noble.brown
Link: https://lkml.kernel.org/r/164859778120.29473.11725907882296224053.stgit@noble.brown
Signed-off-by: NeilBrown <neilb@suse.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Tested-by: David Howells <dhowells@redhat.com>
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Trond Myklebust <trond.myklebust@hammerspace.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Pass a folio instead of a page to aops->is_dirty_writeback().
Convert both implementations and the caller.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Since commit 791b48b642 ("mm: vmscan: scan until it finds eligible
pages"), splicing any skipped pages to the tail of the LRU list won't put
the system at risk of premature OOM but will waste lots of cpu cycles.
Correct the comment accordingly.
Link: https://lkml.kernel.org/r/20220416025231.8082-1-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Since commit 6d6435811c19 ("remove bdi_congested() and wb_congested() and
related functions"), there is no congested backing device check anymore.
Correct the comment accordingly.
[akpm@linux-foundation.org: tweak grammar]
Link: https://lkml.kernel.org/r/20220414120202.30082-1-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Since commit 1431d4d11a ("mm: base LRU balancing on an explicit cost
model"), the relative value of each set of LRU lists is based on cost
model instead of rotated/scanned ratio. Cleanup the relevant comment.
Link: https://lkml.kernel.org/r/20220409030245.61211-1-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
lruvec_lru_size() is only used in get_scan_count(), so the only possible
zone_idx is sc->reclaim_idx. Since sc->reclaim_idx is ensured to be a
valid zone idex, we can remove the extra check for zone iteration.
Link: https://lkml.kernel.org/r/20220317234624.23358-1-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
As mentioned in commit 6aa303defb ("mm, vmscan: only allocate and
reclaim from zones with pages managed by the buddy allocator") , reclaim
only affects managed_zones.
Let's adjust the code and comment accordingly.
Link: https://lkml.kernel.org/r/20220327024101.10378-1-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
- Rewrite how munlock works to massively reduce the contention
on i_mmap_rwsem (Hugh Dickins):
https://lore.kernel.org/linux-mm/8e4356d-9622-a7f0-b2c-f116b5f2efea@google.com/
- Sort out the page refcount mess for ZONE_DEVICE pages (Christoph Hellwig):
https://lore.kernel.org/linux-mm/20220210072828.2930359-1-hch@lst.de/
- Convert GUP to use folios and make pincount available for order-1
pages. (Matthew Wilcox)
- Convert a few more truncation functions to use folios (Matthew Wilcox)
- Convert page_vma_mapped_walk to use PFNs instead of pages (Matthew Wilcox)
- Convert rmap_walk to use folios (Matthew Wilcox)
- Convert most of shrink_page_list() to use a folio (Matthew Wilcox)
- Add support for creating large folios in readahead (Matthew Wilcox)
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Merge tag 'folio-5.18c' of git://git.infradead.org/users/willy/pagecache
Pull folio updates from Matthew Wilcox:
- Rewrite how munlock works to massively reduce the contention on
i_mmap_rwsem (Hugh Dickins):
https://lore.kernel.org/linux-mm/8e4356d-9622-a7f0-b2c-f116b5f2efea@google.com/
- Sort out the page refcount mess for ZONE_DEVICE pages (Christoph
Hellwig):
https://lore.kernel.org/linux-mm/20220210072828.2930359-1-hch@lst.de/
- Convert GUP to use folios and make pincount available for order-1
pages. (Matthew Wilcox)
- Convert a few more truncation functions to use folios (Matthew
Wilcox)
- Convert page_vma_mapped_walk to use PFNs instead of pages (Matthew
Wilcox)
- Convert rmap_walk to use folios (Matthew Wilcox)
- Convert most of shrink_page_list() to use a folio (Matthew Wilcox)
- Add support for creating large folios in readahead (Matthew Wilcox)
* tag 'folio-5.18c' of git://git.infradead.org/users/willy/pagecache: (114 commits)
mm/damon: minor cleanup for damon_pa_young
selftests/vm/transhuge-stress: Support file-backed PMD folios
mm/filemap: Support VM_HUGEPAGE for file mappings
mm/readahead: Switch to page_cache_ra_order
mm/readahead: Align file mappings for non-DAX
mm/readahead: Add large folio readahead
mm: Support arbitrary THP sizes
mm: Make large folios depend on THP
mm: Fix READ_ONLY_THP warning
mm/filemap: Allow large folios to be added to the page cache
mm: Turn can_split_huge_page() into can_split_folio()
mm/vmscan: Convert pageout() to take a folio
mm/vmscan: Turn page_check_references() into folio_check_references()
mm/vmscan: Account large folios correctly
mm/vmscan: Optimise shrink_page_list for non-PMD-sized folios
mm/vmscan: Free non-shmem folios without splitting them
mm/rmap: Constify the rmap_walk_control argument
mm/rmap: Convert rmap_walk() to take a folio
mm: Turn page_anon_vma() into folio_anon_vma()
mm/rmap: Turn page_lock_anon_vma_read() into folio_lock_anon_vma_read()
...
With the advent of various new memory types, some machines will have
multiple types of memory, e.g. DRAM and PMEM (persistent memory). The
memory subsystem of these machines can be called memory tiering system,
because the performance of the different types of memory are usually
different.
In such system, because of the memory accessing pattern changing etc,
some pages in the slow memory may become hot globally. So in this
patch, the NUMA balancing mechanism is enhanced to optimize the page
placement among the different memory types according to hot/cold
dynamically.
In a typical memory tiering system, there are CPUs, fast memory and slow
memory in each physical NUMA node. The CPUs and the fast memory will be
put in one logical node (called fast memory node), while the slow memory
will be put in another (faked) logical node (called slow memory node).
That is, the fast memory is regarded as local while the slow memory is
regarded as remote. So it's possible for the recently accessed pages in
the slow memory node to be promoted to the fast memory node via the
existing NUMA balancing mechanism.
The original NUMA balancing mechanism will stop to migrate pages if the
free memory of the target node becomes below the high watermark. This
is a reasonable policy if there's only one memory type. But this makes
the original NUMA balancing mechanism almost do not work to optimize
page placement among different memory types. Details are as follows.
It's the common cases that the working-set size of the workload is
larger than the size of the fast memory nodes. Otherwise, it's
unnecessary to use the slow memory at all. So, there are almost always
no enough free pages in the fast memory nodes, so that the globally hot
pages in the slow memory node cannot be promoted to the fast memory
node. To solve the issue, we have 2 choices as follows,
a. Ignore the free pages watermark checking when promoting hot pages
from the slow memory node to the fast memory node. This will
create some memory pressure in the fast memory node, thus trigger
the memory reclaiming. So that, the cold pages in the fast memory
node will be demoted to the slow memory node.
b. Define a new watermark called wmark_promo which is higher than
wmark_high, and have kswapd reclaiming pages until free pages reach
such watermark. The scenario is as follows: when we want to promote
hot-pages from a slow memory to a fast memory, but fast memory's free
pages would go lower than high watermark with such promotion, we wake
up kswapd with wmark_promo watermark in order to demote cold pages and
free us up some space. So, next time we want to promote hot-pages we
might have a chance of doing so.
The choice "a" may create high memory pressure in the fast memory node.
If the memory pressure of the workload is high, the memory pressure
may become so high that the memory allocation latency of the workload
is influenced, e.g. the direct reclaiming may be triggered.
The choice "b" works much better at this aspect. If the memory
pressure of the workload is high, the hot pages promotion will stop
earlier because its allocation watermark is higher than that of the
normal memory allocation. So in this patch, choice "b" is implemented.
A new zone watermark (WMARK_PROMO) is added. Which is larger than the
high watermark and can be controlled via watermark_scale_factor.
In addition to the original page placement optimization among sockets,
the NUMA balancing mechanism is extended to be used to optimize page
placement according to hot/cold among different memory types. So the
sysctl user space interface (numa_balancing) is extended in a backward
compatible way as follow, so that the users can enable/disable these
functionality individually.
The sysctl is converted from a Boolean value to a bits field. The
definition of the flags is,
- 0: NUMA_BALANCING_DISABLED
- 1: NUMA_BALANCING_NORMAL
- 2: NUMA_BALANCING_MEMORY_TIERING
We have tested the patch with the pmbench memory accessing benchmark
with the 80:20 read/write ratio and the Gauss access address
distribution on a 2 socket Intel server with Optane DC Persistent
Memory Model. The test results shows that the pmbench score can
improve up to 95.9%.
Thanks Andrew Morton to help fix the document format error.
Link: https://lkml.kernel.org/r/20220221084529.1052339-3-ying.huang@intel.com
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Tested-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Wei Xu <weixugc@google.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: zhongjiang-ali <zhongjiang-ali@linux.alibaba.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Feng Tang <feng.tang@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit b518154e59 ("mm/vmscan: protect the workingset on anonymous
LRU") requires to look twice for both mapped anon/file pages are used
more than once to take the decission of reclaim or activation. Correct
the documentation accordingly.
Link: https://lkml.kernel.org/r/1646925640-21324-1-git-send-email-quic_charante@quicinc.com
Signed-off-by: Charan Teja Kalla <quic_charante@quicinc.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
__isolate_lru_page_prepare() conflates two unrelated functions, with the
flags to one disjoint from the flags to the other; and hides some of the
important checks outside of isolate_migratepages_block(), where the
sequence is better to be visible. It comes from the days of lumpy
reclaim, before compaction, when the combination made more sense.
Move what's needed by mm/compaction.c isolate_migratepages_block() inline
there, and what's needed by mm/vmscan.c isolate_lru_pages() inline there.
Shorten "isolate_mode" to "mode", so the sequence of conditions is easier
to read. Declare a "mapping" variable, to save one call to page_mapping()
(but not another: calling again after page is locked is necessary).
Simplify isolate_lru_pages() with a "move_to" list pointer.
Link: https://lkml.kernel.org/r/879d62a8-91cc-d3c6-fb3b-69768236df68@google.com
Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: David Rientjes <rientjes@google.com>
Reviewed-by: Alex Shi <alexs@kernel.org>
Cc: Alexander Duyck <alexander.duyck@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
PF_SWAPWRITE has been redundant since v3.2 commit ee72886d8e ("mm:
vmscan: do not writeback filesystem pages in direct reclaim").
Coincidentally, NeilBrown's current patch "remove inode_congested()"
deletes may_write_to_inode(), which appeared to be the one function which
took notice of PF_SWAPWRITE. But if you study the old logic, and the
conditions under which may_write_to_inode() was called, you discover that
flag and function have been pointless for a decade.
Link: https://lkml.kernel.org/r/75e80e7-742d-e3bd-531-614db8961e4@google.com
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: NeilBrown <neilb@suse.de>
Cc: Jan Kara <jack@suse.de>
Cc: "Darrick J. Wong" <djwong@kernel.org>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
These functions are no longer useful as no BDIs report congestions any
more.
Removing the test on bdi_write_contested() in current_may_throttle()
could cause a small change in behaviour, but only when PF_LOCAL_THROTTLE
is set.
So replace the calls by 'false' and simplify the code - and remove the
functions.
[akpm@linux-foundation.org: fix build]
Link: https://lkml.kernel.org/r/164549983742.9187.2570198746005819592.stgit@noble.brown
Signed-off-by: NeilBrown <neilb@suse.de>
Acked-by: Ryusuke Konishi <konishi.ryusuke@gmail.com> [nilfs]
Cc: Anna Schumaker <Anna.Schumaker@Netapp.com>
Cc: Chao Yu <chao@kernel.org>
Cc: Darrick J. Wong <djwong@kernel.org>
Cc: Ilya Dryomov <idryomov@gmail.com>
Cc: Jaegeuk Kim <jaegeuk@kernel.org>
Cc: Jan Kara <jack@suse.cz>
Cc: Jeff Layton <jlayton@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Lars Ellenberg <lars.ellenberg@linbit.com>
Cc: Miklos Szeredi <miklos@szeredi.hu>
Cc: Paolo Valente <paolo.valente@linaro.org>
Cc: Philipp Reisner <philipp.reisner@linbit.com>
Cc: Trond Myklebust <trond.myklebust@hammerspace.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
inode_congested() reports if the backing-device for the inode is
congested. No bdi reports congestion any more, so this always returns
'false'.
So remove inode_congested() and related functions, and remove the call
sites, assuming that inode_congested() always returns 'false'.
Link: https://lkml.kernel.org/r/164549983741.9187.2174285592262191311.stgit@noble.brown
Signed-off-by: NeilBrown <neilb@suse.de>
Cc: Anna Schumaker <Anna.Schumaker@Netapp.com>
Cc: Chao Yu <chao@kernel.org>
Cc: Darrick J. Wong <djwong@kernel.org>
Cc: Ilya Dryomov <idryomov@gmail.com>
Cc: Jaegeuk Kim <jaegeuk@kernel.org>
Cc: Jan Kara <jack@suse.cz>
Cc: Jeff Layton <jlayton@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Lars Ellenberg <lars.ellenberg@linbit.com>
Cc: Miklos Szeredi <miklos@szeredi.hu>
Cc: Paolo Valente <paolo.valente@linaro.org>
Cc: Philipp Reisner <philipp.reisner@linbit.com>
Cc: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Cc: Trond Myklebust <trond.myklebust@hammerspace.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This function already required a head page to be passed, so this
just adds type-safety and removes a few implicit calls to
compound_head().
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
We always write out an entire folio at once. This conversion removes
a few calls to compound_head() and gets the NR_VMSCAN_WRITE statistic
right when writing out a large folio.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
This function only has one caller, and it already has a folio. This
removes a number of calls to compound_head().
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
The statistics we gather should count the number of pages, not the
number of folios. The logic in this function is somewhat convoluted,
but even if we split the folio, I think the accounting is now correct.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
A large folio which is smaller than a PMD does not need to do the extra
work in try_to_unmap() of trying to split a PMD entry.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
We have to allocate memory in order to split a file-backed folio, so
it's not a good idea to split them in the memory freeing path. It also
doesn't work for XFS because pages have an extra reference count from
page_has_private() and split_huge_page() expects that reference to have
already been removed. Unfortunately, we still have to split shmem THPs
because we can't handle swapping out an entire THP yet.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Both its callers pass a page which was previously on an LRU list,
so were passing a folio by definition. Use the type system to enforce
that and remove a few calls to compound_head().
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
This is a convenience function; split_huge_page_to_list() can take
any page in a folio (and does so on purpose because that page will
be the one which keeps the refcount). But it's convenient for the
callers to pass the folio instead of the first page in the folio.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Add kernel-doc and return the number of pages removed in order to
get the statistics right in __invalidate_mapping_pages().
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
This removes a few hidden calls to compound_head().
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Add a putback_lru_page() wrapper. Removes a couple of compound_head()
calls.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
This removes an assumption that THPs are the only kind of compound
pages and removes a couple of hidden calls to compound_head. It
also documents that you can't pass a tail page to mem_cgroup_swapout().
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
This removes an assumption that THPs are the only kind of compound
pages and removes a few hidden calls to compound_head().
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Add isolate_lru_page() as a wrapper around isolate_lru_folio().
TestClearPageLRU() would have always failed on a tail page, so
returning -EBUSY is the same behaviour.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
4.8 commit 7751b2da6b ("vmscan: split file huge pages before paging
them out") inserted a split_huge_page_to_list() into shrink_page_list()
without considering the mlock case: no problem if the page has already
been marked as Mlocked (the !page_evictable check much higher up will
have skipped all this), but it has always been the case that races or
omissions in setting Mlocked can rely on page reclaim to detect this
and correct it before actually reclaiming - and that remains so, but
what a shame if a hugepage is needlessly split before discovering it.
It is surprising that page_check_references() returns PAGEREF_RECLAIM
when VM_LOCKED, but there was a good reason for that: try_to_unmap_one()
is where the condition is detected and corrected; and until now it could
not be done in page_referenced_one(), because that does not always have
the page locked. Now that mlock's requirement for page lock has gone,
copy try_to_unmap_one()'s mlock restoration into page_referenced_one(),
and let page_check_references() return PAGEREF_ACTIVATE in this case.
But page_referenced_one() may find a pte mapping one part of a hugepage:
what hold should a pte mapped in a VM_LOCKED area exert over the entire
huge page? That's debatable. The approach taken here is to treat that
pte mapping in page_referenced_one() as if not VM_LOCKED, and if no
VM_LOCKED pmd mapping is found later in the walk, and lack of reference
permits, then PAGEREF_RECLAIM take it to attempted splitting as before.
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
A soft lockup bug in kcompactd was reported in a private bugzilla with
the following visible in dmesg;
watchdog: BUG: soft lockup - CPU#33 stuck for 26s! [kcompactd0:479]
watchdog: BUG: soft lockup - CPU#33 stuck for 52s! [kcompactd0:479]
watchdog: BUG: soft lockup - CPU#33 stuck for 78s! [kcompactd0:479]
watchdog: BUG: soft lockup - CPU#33 stuck for 104s! [kcompactd0:479]
The machine had 256G of RAM with no swap and an earlier failed
allocation indicated that node 0 where kcompactd was run was potentially
unreclaimable;
Node 0 active_anon:29355112kB inactive_anon:2913528kB active_file:0kB
inactive_file:0kB unevictable:64kB isolated(anon):0kB isolated(file):0kB
mapped:8kB dirty:0kB writeback:0kB shmem:26780kB shmem_thp:
0kB shmem_pmdmapped: 0kB anon_thp: 23480320kB writeback_tmp:0kB
kernel_stack:2272kB pagetables:24500kB all_unreclaimable? yes
Vlastimil Babka investigated a crash dump and found that a task
migrating pages was trying to drain PCP lists;
PID: 52922 TASK: ffff969f820e5000 CPU: 19 COMMAND: "kworker/u128:3"
Call Trace:
__schedule
schedule
schedule_timeout
wait_for_completion
__flush_work
__drain_all_pages
__alloc_pages_slowpath.constprop.114
__alloc_pages
alloc_migration_target
migrate_pages
migrate_to_node
do_migrate_pages
cpuset_migrate_mm_workfn
process_one_work
worker_thread
kthread
ret_from_fork
This failure is specific to CONFIG_PREEMPT=n builds. The root of the
problem is that kcompact0 is not rescheduling on a CPU while a task that
has isolated a large number of the pages from the LRU is waiting on
kcompact0 to reschedule so the pages can be released. While
shrink_inactive_list() only loops once around too_many_isolated, reclaim
can continue without rescheduling if sc->skipped_deactivate == 1 which
could happen if there was no file LRU and the inactive anon list was not
low.
Link: https://lkml.kernel.org/r/20220203100326.GD3301@suse.de
Fixes: d818fca1ca ("mm/vmscan: throttle reclaim and compaction when too may pages are isolated")
Signed-off-by: Mel Gorman <mgorman@suse.de>
Debugged-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
drop_slab_node is only used in drop_slab. So remove it's declaration
from header file and add keyword static for it's definition.
Link: https://lkml.kernel.org/r/20211111062445.5236-1-ligang.bdlg@bytedance.com
Signed-off-by: Gang Li <ligang.bdlg@bytedance.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Hugh Dickins reported the following
My tmpfs swapping load (tweaked to use huge pages more heavily
than in real life) is far from being a realistic load: but it was
notably slowed down by your throttling mods in 5.16-rc, and this
patch makes it well again - thanks.
But: it very quickly hit NULL pointer until I changed that last
line to
if (first_pgdat)
consider_reclaim_throttle(first_pgdat, sc);
The likely issue is that huge pages are a major component of the test
workload. When this is the case, first_pgdat may never get set if
compaction is ready to continue due to this check
if (IS_ENABLED(CONFIG_COMPACTION) &&
sc->order > PAGE_ALLOC_COSTLY_ORDER &&
compaction_ready(zone, sc)) {
sc->compaction_ready = true;
continue;
}
If this was true for every zone in the zonelist, first_pgdat would never
get set resulting in a NULL pointer exception.
Link: https://lkml.kernel.org/r/20211209095453.GM3366@techsingularity.net
Fixes: 1b4e3f26f9 ("mm: vmscan: Reduce throttling due to a failure to make progress")
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Reported-by: Hugh Dickins <hughd@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Rik van Riel <riel@surriel.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Darrick J. Wong <djwong@kernel.org>
Cc: Shakeel Butt <shakeelb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Mike Galbraith, Alexey Avramov and Darrick Wong all reported similar
problems due to reclaim throttling for excessive lengths of time. In
Alexey's case, a memory hog that should go OOM quickly stalls for
several minutes before stalling. In Mike and Darrick's cases, a small
memcg environment stalled excessively even though the system had enough
memory overall.
Commit 69392a403f ("mm/vmscan: throttle reclaim when no progress is
being made") introduced the problem although commit a19594ca4a
("mm/vmscan: increase the timeout if page reclaim is not making
progress") made it worse. Systems at or near an OOM state that cannot
be recovered must reach OOM quickly and memcg should kill tasks if a
memcg is near OOM.
To address this, only stall for the first zone in the zonelist, reduce
the timeout to 1 tick for VMSCAN_THROTTLE_NOPROGRESS and only stall if
the scan control nr_reclaimed is 0, kswapd is still active and there
were excessive pages pending for writeback. If kswapd has stopped
reclaiming due to excessive failures, do not stall at all so that OOM
triggers relatively quickly. Similarly, if an LRU is simply congested,
only lightly throttle similar to NOPROGRESS.
Alexey's original case was the most straight forward
for i in {1..3}; do tail /dev/zero; done
On vanilla 5.16-rc1, this test stalled heavily, after the patch the test
completes in a few seconds similar to 5.15.
Alexey's second test case added watching a youtube video while tail runs
10 times. On 5.15, playback only jitters slightly, 5.16-rc1 stalls a
lot with lots of frames missing and numerous audio glitches. With this
patch applies, the video plays similarly to 5.15.
[lkp@intel.com: Fix W=1 build warning]
Link: https://lore.kernel.org/r/99e779783d6c7fce96448a3402061b9dc1b3b602.camel@gmx.de
Link: https://lore.kernel.org/r/20211124011954.7cab9bb4@mail.inbox.lv
Link: https://lore.kernel.org/r/20211022144651.19914-1-mgorman@techsingularity.net
Link: https://lore.kernel.org/r/20211202150614.22440-1-mgorman@techsingularity.net
Link: https://linux-regtracking.leemhuis.info/regzbot/regression/20211124011954.7cab9bb4@mail.inbox.lv/
Reported-and-tested-by: Alexey Avramov <hakavlad@inbox.lv>
Reported-and-tested-by: Mike Galbraith <efault@gmx.de>
Reported-and-tested-by: Darrick J. Wong <djwong@kernel.org>
Reported-by: kernel test robot <lkp@intel.com>
Acked-by: Hugh Dickins <hughd@google.com>
Tracked-by: Thorsten Leemhuis <regressions@leemhuis.info>
Fixes: 69392a403f ("mm/vmscan: throttle reclaim when no progress is being made")
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Merge more updates from Andrew Morton:
"87 patches.
Subsystems affected by this patch series: mm (pagecache and hugetlb),
procfs, misc, MAINTAINERS, lib, checkpatch, binfmt, kallsyms, ramfs,
init, codafs, nilfs2, hfs, crash_dump, signals, seq_file, fork,
sysvfs, kcov, gdb, resource, selftests, and ipc"
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (87 commits)
ipc/ipc_sysctl.c: remove fallback for !CONFIG_PROC_SYSCTL
ipc: check checkpoint_restore_ns_capable() to modify C/R proc files
selftests/kselftest/runner/run_one(): allow running non-executable files
virtio-mem: disallow mapping virtio-mem memory via /dev/mem
kernel/resource: disallow access to exclusive system RAM regions
kernel/resource: clean up and optimize iomem_is_exclusive()
scripts/gdb: handle split debug for vmlinux
kcov: replace local_irq_save() with a local_lock_t
kcov: avoid enable+disable interrupts if !in_task()
kcov: allocate per-CPU memory on the relevant node
Documentation/kcov: define `ip' in the example
Documentation/kcov: include types.h in the example
sysv: use BUILD_BUG_ON instead of runtime check
kernel/fork.c: unshare(): use swap() to make code cleaner
seq_file: fix passing wrong private data
seq_file: move seq_escape() to a header
signal: remove duplicate include in signal.h
crash_dump: remove duplicate include in crash_dump.h
crash_dump: fix boolreturn.cocci warning
hfs/hfsplus: use WARN_ON for sanity check
...
Historically (pre-2.5), the inode shrinker used to reclaim only empty
inodes and skip over those that still contained page cache. This caused
problems on highmem hosts: struct inode could put fill lowmem zones
before the cache was getting reclaimed in the highmem zones.
To address this, the inode shrinker started to strip page cache to
facilitate reclaiming lowmem. However, this comes with its own set of
problems: the shrinkers may drop actively used page cache just because
the inodes are not currently open or dirty - think working with a large
git tree. It further doesn't respect cgroup memory protection settings
and can cause priority inversions between containers.
Nowadays, the page cache also holds non-resident info for evicted cache
pages in order to detect refaults. We've come to rely heavily on this
data inside reclaim for protecting the cache workingset and driving swap
behavior. We also use it to quantify and report workload health through
psi. The latter in turn is used for fleet health monitoring, as well as
driving automated memory sizing of workloads and containers, proactive
reclaim and memory offloading schemes.
The consequences of dropping page cache prematurely is that we're seeing
subtle and not-so-subtle failures in all of the above-mentioned
scenarios, with the workload generally entering unexpected thrashing
states while losing the ability to reliably detect it.
To fix this on non-highmem systems at least, going back to rotating
inodes on the LRU isn't feasible. We've tried (commit a76cf1a474
("mm: don't reclaim inodes with many attached pages")) and failed
(commit 69056ee6a8 ("Revert "mm: don't reclaim inodes with many
attached pages"")).
The issue is mostly that shrinker pools attract pressure based on their
size, and when objects get skipped the shrinkers remember this as
deferred reclaim work. This accumulates excessive pressure on the
remaining inodes, and we can quickly eat into heavily used ones, or
dirty ones that require IO to reclaim, when there potentially is plenty
of cold, clean cache around still.
Instead, this patch keeps populated inodes off the inode LRU in the
first place - just like an open file or dirty state would. An otherwise
clean and unused inode then gets queued when the last cache entry
disappears. This solves the problem without reintroducing the reclaim
issues, and generally is a bit more scalable than having to wade through
potentially hundreds of thousands of busy inodes.
Locking is a bit tricky because the locks protecting the inode state
(i_lock) and the inode LRU (lru_list.lock) don't nest inside the
irq-safe page cache lock (i_pages.xa_lock). Page cache deletions are
serialized through i_lock, taken before the i_pages lock, to make sure
depopulated inodes are queued reliably. Additions may race with
deletions, but we'll check again in the shrinker. If additions race
with the shrinker itself, we're protected by the i_lock: if find_inode()
or iput() win, the shrinker will bail on the elevated i_count or
I_REFERENCED; if the shrinker wins and goes ahead with the inode, it
will set I_FREEING and inhibit further igets(), which will cause the
other side to create a new instance of the inode instead.
Link: https://lkml.kernel.org/r/20210614211904.14420-4-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Roman Gushchin <guro@fb.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Dave Chinner <david@fromorbit.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Merge misc updates from Andrew Morton:
"257 patches.
Subsystems affected by this patch series: scripts, ocfs2, vfs, and
mm (slab-generic, slab, slub, kconfig, dax, kasan, debug, pagecache,
gup, swap, memcg, pagemap, mprotect, mremap, iomap, tracing, vmalloc,
pagealloc, memory-failure, hugetlb, userfaultfd, vmscan, tools,
memblock, oom-kill, hugetlbfs, migration, thp, readahead, nommu, ksm,
vmstat, madvise, memory-hotplug, rmap, zsmalloc, highmem, zram,
cleanups, kfence, and damon)"
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (257 commits)
mm/damon: remove return value from before_terminate callback
mm/damon: fix a few spelling mistakes in comments and a pr_debug message
mm/damon: simplify stop mechanism
Docs/admin-guide/mm/pagemap: wordsmith page flags descriptions
Docs/admin-guide/mm/damon/start: simplify the content
Docs/admin-guide/mm/damon/start: fix a wrong link
Docs/admin-guide/mm/damon/start: fix wrong example commands
mm/damon/dbgfs: add adaptive_targets list check before enable monitor_on
mm/damon: remove unnecessary variable initialization
Documentation/admin-guide/mm/damon: add a document for DAMON_RECLAIM
mm/damon: introduce DAMON-based Reclamation (DAMON_RECLAIM)
selftests/damon: support watermarks
mm/damon/dbgfs: support watermarks
mm/damon/schemes: activate schemes based on a watermarks mechanism
tools/selftests/damon: update for regions prioritization of schemes
mm/damon/dbgfs: support prioritization weights
mm/damon/vaddr,paddr: support pageout prioritization
mm/damon/schemes: prioritize regions within the quotas
mm/damon/selftests: support schemes quotas
mm/damon/dbgfs: support quotas of schemes
...
Tracing indicates that tasks throttled on NOPROGRESS are woken
prematurely resulting in occasional massive spikes in direct reclaim
activity. This patch wakes tasks throttled on NOPROGRESS if reclaim
efficiency is at least 12%.
Link: https://lkml.kernel.org/r/20211022144651.19914-9-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: "Darrick J . Wong" <djwong@kernel.org>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: NeilBrown <neilb@suse.de>
Cc: Rik van Riel <riel@surriel.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Tracing of the stutterp workload showed the following delays
1 usect_delayed=124000 reason=VMSCAN_THROTTLE_NOPROGRESS
1 usect_delayed=128000 reason=VMSCAN_THROTTLE_NOPROGRESS
1 usect_delayed=176000 reason=VMSCAN_THROTTLE_NOPROGRESS
1 usect_delayed=536000 reason=VMSCAN_THROTTLE_NOPROGRESS
1 usect_delayed=544000 reason=VMSCAN_THROTTLE_NOPROGRESS
1 usect_delayed=556000 reason=VMSCAN_THROTTLE_NOPROGRESS
1 usect_delayed=624000 reason=VMSCAN_THROTTLE_NOPROGRESS
1 usect_delayed=716000 reason=VMSCAN_THROTTLE_NOPROGRESS
1 usect_delayed=772000 reason=VMSCAN_THROTTLE_NOPROGRESS
2 usect_delayed=512000 reason=VMSCAN_THROTTLE_NOPROGRESS
16 usect_delayed=120000 reason=VMSCAN_THROTTLE_NOPROGRESS
53 usect_delayed=116000 reason=VMSCAN_THROTTLE_NOPROGRESS
116 usect_delayed=112000 reason=VMSCAN_THROTTLE_NOPROGRESS
5907 usect_delayed=108000 reason=VMSCAN_THROTTLE_NOPROGRESS
71741 usect_delayed=104000 reason=VMSCAN_THROTTLE_NOPROGRESS
All the throttling hit the full timeout and then there was wakeup delays
meaning that the wakeups are premature as no other reclaimer such as
kswapd has made progress. This patch increases the maximum timeout.
Link: https://lkml.kernel.org/r/20211022144651.19914-8-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: "Darrick J . Wong" <djwong@kernel.org>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: NeilBrown <neilb@suse.de>
Cc: Rik van Riel <riel@surriel.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Neil Brown raised concerns about callers of reclaim_throttle specifying
a timeout value. The original timeout values to congestion_wait() were
probably pulled out of thin air or copy&pasted from somewhere else.
This patch centralises the timeout values and selects a timeout based on
the reason for reclaim throttling. These figures are also pulled out of
the same thin air but better values may be derived
Running a workload that is throttling for inappropriate periods and
tracing mm_vmscan_throttled can be used to pick a more appropriate
value. Excessive throttling would pick a lower timeout where as
excessive CPU usage in reclaim context would select a larger timeout.
Ideally a large value would always be used and the wakeups would occur
before a timeout but that requires careful testing.
Link: https://lkml.kernel.org/r/20211022144651.19914-7-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: "Darrick J . Wong" <djwong@kernel.org>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: NeilBrown <neilb@suse.de>
Cc: Rik van Riel <riel@surriel.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Memcg reclaim throttles on congestion if no reclaim progress is made.
This makes little sense, it might be due to writeback or a host of other
factors.
For !memcg reclaim, it's messy. Direct reclaim primarily is throttled
in the page allocator if it is failing to make progress. Kswapd
throttles if too many pages are under writeback and marked for immediate
reclaim.
This patch explicitly throttles if reclaim is failing to make progress.
[vbabka@suse.cz: Remove redundant code]
Link: https://lkml.kernel.org/r/20211022144651.19914-4-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: "Darrick J . Wong" <djwong@kernel.org>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: NeilBrown <neilb@suse.de>
Cc: Rik van Riel <riel@surriel.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Page reclaim throttles on congestion if too many parallel reclaim
instances have isolated too many pages. This makes no sense, excessive
parallelisation has nothing to do with writeback or congestion.
This patch creates an additional workqueue to sleep on when too many
pages are isolated. The throttled tasks are woken when the number of
isolated pages is reduced or a timeout occurs. There may be some false
positive wakeups for GFP_NOIO/GFP_NOFS callers but the tasks will
throttle again if necessary.
[shy828301@gmail.com: Wake up from compaction context]
[vbabka@suse.cz: Account number of throttled tasks only for writeback]
Link: https://lkml.kernel.org/r/20211022144651.19914-3-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: "Darrick J . Wong" <djwong@kernel.org>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: NeilBrown <neilb@suse.de>
Cc: Rik van Riel <riel@surriel.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "Remove dependency on congestion_wait in mm/", v5.
This series that removes all calls to congestion_wait in mm/ and deletes
wait_iff_congested. It's not a clever implementation but
congestion_wait has been broken for a long time [1].
Even if congestion throttling worked, it was never a great idea. While
excessive dirty/writeback pages at the tail of the LRU is one
possibility that reclaim may be slow, there is also the problem of too
many pages being isolated and reclaim failing for other reasons
(elevated references, too many pages isolated, excessive LRU contention
etc).
This series replaces the "congestion" throttling with 3 different types.
- If there are too many dirty/writeback pages, sleep until a timeout or
enough pages get cleaned
- If too many pages are isolated, sleep until enough isolated pages are
either reclaimed or put back on the LRU
- If no progress is being made, direct reclaim tasks sleep until
another task makes progress with acceptable efficiency.
This was initially tested with a mix of workloads that used to trigger
corner cases that no longer work. A new test case was created called
"stutterp" (pagereclaim-stutterp-noreaders in mmtests) using a freshly
created XFS filesystem. Note that it may be necessary to increase the
timeout of ssh if executing remotely as ssh itself can get throttled and
the connection may timeout.
stutterp varies the number of "worker" processes from 4 up to NR_CPUS*4
to check the impact as the number of direct reclaimers increase. It has
four types of worker.
- One "anon latency" worker creates small mappings with mmap() and
times how long it takes to fault the mapping reading it 4K at a time
- X file writers which is fio randomly writing X files where the total
size of the files add up to the allowed dirty_ratio. fio is allowed
to run for a warmup period to allow some file-backed pages to
accumulate. The duration of the warmup is based on the best-case
linear write speed of the storage.
- Y file readers which is fio randomly reading small files
- Z anon memory hogs which continually map (100-dirty_ratio)% of memory
- Total estimated WSS = (100+dirty_ration) percentage of memory
X+Y+Z+1 == NR_WORKERS varying from 4 up to NR_CPUS*4
The intent is to maximise the total WSS with a mix of file and anon
memory where some anonymous memory must be swapped and there is a high
likelihood of dirty/writeback pages reaching the end of the LRU.
The test can be configured to have no background readers to stress
dirty/writeback pages. The results below are based on having zero
readers.
The short summary of the results is that the series works and stalls
until some event occurs but the timeouts may need adjustment.
The test results are not broken down by patch as the series should be
treated as one block that replaces a broken throttling mechanism with a
working one.
Finally, three machines were tested but I'm reporting the worst set of
results. The other two machines had much better latencies for example.
First the results of the "anon latency" latency
stutterp
5.15.0-rc1 5.15.0-rc1
vanilla mm-reclaimcongest-v5r4
Amean mmap-4 31.4003 ( 0.00%) 2661.0198 (-8374.52%)
Amean mmap-7 38.1641 ( 0.00%) 149.2891 (-291.18%)
Amean mmap-12 60.0981 ( 0.00%) 187.8105 (-212.51%)
Amean mmap-21 161.2699 ( 0.00%) 213.9107 ( -32.64%)
Amean mmap-30 174.5589 ( 0.00%) 377.7548 (-116.41%)
Amean mmap-48 8106.8160 ( 0.00%) 1070.5616 ( 86.79%)
Stddev mmap-4 41.3455 ( 0.00%) 27573.9676 (-66591.66%)
Stddev mmap-7 53.5556 ( 0.00%) 4608.5860 (-8505.23%)
Stddev mmap-12 171.3897 ( 0.00%) 5559.4542 (-3143.75%)
Stddev mmap-21 1506.6752 ( 0.00%) 5746.2507 (-281.39%)
Stddev mmap-30 557.5806 ( 0.00%) 7678.1624 (-1277.05%)
Stddev mmap-48 61681.5718 ( 0.00%) 14507.2830 ( 76.48%)
Max-90 mmap-4 31.4243 ( 0.00%) 83.1457 (-164.59%)
Max-90 mmap-7 41.0410 ( 0.00%) 41.0720 ( -0.08%)
Max-90 mmap-12 66.5255 ( 0.00%) 53.9073 ( 18.97%)
Max-90 mmap-21 146.7479 ( 0.00%) 105.9540 ( 27.80%)
Max-90 mmap-30 193.9513 ( 0.00%) 64.3067 ( 66.84%)
Max-90 mmap-48 277.9137 ( 0.00%) 591.0594 (-112.68%)
Max mmap-4 1913.8009 ( 0.00%) 299623.9695 (-15555.96%)
Max mmap-7 2423.9665 ( 0.00%) 204453.1708 (-8334.65%)
Max mmap-12 6845.6573 ( 0.00%) 221090.3366 (-3129.64%)
Max mmap-21 56278.6508 ( 0.00%) 213877.3496 (-280.03%)
Max mmap-30 19716.2990 ( 0.00%) 216287.6229 (-997.00%)
Max mmap-48 477923.9400 ( 0.00%) 245414.8238 ( 48.65%)
For most thread counts, the time to mmap() is unfortunately increased.
In earlier versions of the series, this was lower but a large number of
throttling events were reaching their timeout increasing the amount of
inefficient scanning of the LRU. There is no prioritisation of reclaim
tasks making progress based on each tasks rate of page allocation versus
progress of reclaim. The variance is also impacted for high worker
counts but in all cases, the differences in latency are not
statistically significant due to very large maximum outliers. Max-90
shows that 90% of the stalls are comparable but the Max results show the
massive outliers which are increased to to stalling.
It is expected that this will be very machine dependant. Due to the
test design, reclaim is difficult so allocations stall and there are
variances depending on whether THPs can be allocated or not. The amount
of memory will affect exactly how bad the corner cases are and how often
they trigger. The warmup period calculation is not ideal as it's based
on linear writes where as fio is randomly writing multiple files from
multiple tasks so the start state of the test is variable. For example,
these are the latencies on a single-socket machine that had more memory
Amean mmap-4 42.2287 ( 0.00%) 49.6838 * -17.65%*
Amean mmap-7 216.4326 ( 0.00%) 47.4451 * 78.08%*
Amean mmap-12 2412.0588 ( 0.00%) 51.7497 ( 97.85%)
Amean mmap-21 5546.2548 ( 0.00%) 51.8862 ( 99.06%)
Amean mmap-30 1085.3121 ( 0.00%) 72.1004 ( 93.36%)
The overall system CPU usage and elapsed time is as follows
5.15.0-rc3 5.15.0-rc3
vanilla mm-reclaimcongest-v5r4
Duration User 6989.03 983.42
Duration System 7308.12 799.68
Duration Elapsed 2277.67 2092.98
The patches reduce system CPU usage by 89% as the vanilla kernel is rarely
stalling.
The high-level /proc/vmstats show
5.15.0-rc1 5.15.0-rc1
vanilla mm-reclaimcongest-v5r2
Ops Direct pages scanned 1056608451.00 503594991.00
Ops Kswapd pages scanned 109795048.00 147289810.00
Ops Kswapd pages reclaimed 63269243.00 31036005.00
Ops Direct pages reclaimed 10803973.00 6328887.00
Ops Kswapd efficiency % 57.62 21.07
Ops Kswapd velocity 48204.98 57572.86
Ops Direct efficiency % 1.02 1.26
Ops Direct velocity 463898.83 196845.97
Kswapd scanned less pages but the detailed pattern is different. The
vanilla kernel scans slowly over time where as the patches exhibits
burst patterns of scan activity. Direct reclaim scanning is reduced by
52% due to stalling.
The pattern for stealing pages is also slightly different. Both kernels
exhibit spikes but the vanilla kernel when reclaiming shows pages being
reclaimed over a period of time where as the patches tend to reclaim in
spikes. The difference is that vanilla is not throttling and instead
scanning constantly finding some pages over time where as the patched
kernel throttles and reclaims in spikes.
Ops Percentage direct scans 90.59 77.37
For direct reclaim, vanilla scanned 90.59% of pages where as with the
patches, 77.37% were direct reclaim due to throttling
Ops Page writes by reclaim 2613590.00 1687131.00
Page writes from reclaim context are reduced.
Ops Page writes anon 2932752.00 1917048.00
And there is less swapping.
Ops Page reclaim immediate 996248528.00 107664764.00
The number of pages encountered at the tail of the LRU tagged for
immediate reclaim but still dirty/writeback is reduced by 89%.
Ops Slabs scanned 164284.00 153608.00
Slab scan activity is similar.
ftrace was used to gather stall activity
Vanilla
-------
1 writeback_wait_iff_congested: usec_timeout=100000 usec_delayed=16000
2 writeback_wait_iff_congested: usec_timeout=100000 usec_delayed=12000
8 writeback_wait_iff_congested: usec_timeout=100000 usec_delayed=8000
29 writeback_wait_iff_congested: usec_timeout=100000 usec_delayed=4000
82394 writeback_wait_iff_congested: usec_timeout=100000 usec_delayed=0
The fast majority of wait_iff_congested calls do not stall at all. What
is likely happening is that cond_resched() reschedules the task for a
short period when the BDI is not registering congestion (which it never
will in this test setup).
1 writeback_congestion_wait: usec_timeout=100000 usec_delayed=120000
2 writeback_congestion_wait: usec_timeout=100000 usec_delayed=132000
4 writeback_congestion_wait: usec_timeout=100000 usec_delayed=112000
380 writeback_congestion_wait: usec_timeout=100000 usec_delayed=108000
778 writeback_congestion_wait: usec_timeout=100000 usec_delayed=104000
congestion_wait if called always exceeds the timeout as there is no
trigger to wake it up.
Bottom line: Vanilla will throttle but it's not effective.
Patch series
------------
Kswapd throttle activity was always due to scanning pages tagged for
immediate reclaim at the tail of the LRU
1 usec_timeout=100000 usect_delayed=72000 reason=VMSCAN_THROTTLE_WRITEBACK
4 usec_timeout=100000 usect_delayed=20000 reason=VMSCAN_THROTTLE_WRITEBACK
5 usec_timeout=100000 usect_delayed=12000 reason=VMSCAN_THROTTLE_WRITEBACK
6 usec_timeout=100000 usect_delayed=16000 reason=VMSCAN_THROTTLE_WRITEBACK
11 usec_timeout=100000 usect_delayed=100000 reason=VMSCAN_THROTTLE_WRITEBACK
11 usec_timeout=100000 usect_delayed=8000 reason=VMSCAN_THROTTLE_WRITEBACK
94 usec_timeout=100000 usect_delayed=0 reason=VMSCAN_THROTTLE_WRITEBACK
112 usec_timeout=100000 usect_delayed=4000 reason=VMSCAN_THROTTLE_WRITEBACK
The majority of events did not stall or stalled for a short period.
Roughly 16% of stalls reached the timeout before expiry. For direct
reclaim, the number of times stalled for each reason were
6624 reason=VMSCAN_THROTTLE_ISOLATED
93246 reason=VMSCAN_THROTTLE_NOPROGRESS
96934 reason=VMSCAN_THROTTLE_WRITEBACK
The most common reason to stall was due to excessive pages tagged for
immediate reclaim at the tail of the LRU followed by a failure to make
forward. A relatively small number were due to too many pages isolated
from the LRU by parallel threads
For VMSCAN_THROTTLE_ISOLATED, the breakdown of delays was
9 usec_timeout=20000 usect_delayed=4000 reason=VMSCAN_THROTTLE_ISOLATED
12 usec_timeout=20000 usect_delayed=16000 reason=VMSCAN_THROTTLE_ISOLATED
83 usec_timeout=20000 usect_delayed=20000 reason=VMSCAN_THROTTLE_ISOLATED
6520 usec_timeout=20000 usect_delayed=0 reason=VMSCAN_THROTTLE_ISOLATED
Most did not stall at all. A small number reached the timeout.
For VMSCAN_THROTTLE_NOPROGRESS, the breakdown of stalls were all over
the map
1 usec_timeout=500000 usect_delayed=324000 reason=VMSCAN_THROTTLE_NOPROGRESS
1 usec_timeout=500000 usect_delayed=332000 reason=VMSCAN_THROTTLE_NOPROGRESS
1 usec_timeout=500000 usect_delayed=348000 reason=VMSCAN_THROTTLE_NOPROGRESS
1 usec_timeout=500000 usect_delayed=360000 reason=VMSCAN_THROTTLE_NOPROGRESS
2 usec_timeout=500000 usect_delayed=228000 reason=VMSCAN_THROTTLE_NOPROGRESS
2 usec_timeout=500000 usect_delayed=260000 reason=VMSCAN_THROTTLE_NOPROGRESS
2 usec_timeout=500000 usect_delayed=340000 reason=VMSCAN_THROTTLE_NOPROGRESS
2 usec_timeout=500000 usect_delayed=364000 reason=VMSCAN_THROTTLE_NOPROGRESS
2 usec_timeout=500000 usect_delayed=372000 reason=VMSCAN_THROTTLE_NOPROGRESS
2 usec_timeout=500000 usect_delayed=428000 reason=VMSCAN_THROTTLE_NOPROGRESS
2 usec_timeout=500000 usect_delayed=460000 reason=VMSCAN_THROTTLE_NOPROGRESS
2 usec_timeout=500000 usect_delayed=464000 reason=VMSCAN_THROTTLE_NOPROGRESS
3 usec_timeout=500000 usect_delayed=244000 reason=VMSCAN_THROTTLE_NOPROGRESS
3 usec_timeout=500000 usect_delayed=252000 reason=VMSCAN_THROTTLE_NOPROGRESS
3 usec_timeout=500000 usect_delayed=272000 reason=VMSCAN_THROTTLE_NOPROGRESS
4 usec_timeout=500000 usect_delayed=188000 reason=VMSCAN_THROTTLE_NOPROGRESS
4 usec_timeout=500000 usect_delayed=268000 reason=VMSCAN_THROTTLE_NOPROGRESS
4 usec_timeout=500000 usect_delayed=328000 reason=VMSCAN_THROTTLE_NOPROGRESS
4 usec_timeout=500000 usect_delayed=380000 reason=VMSCAN_THROTTLE_NOPROGRESS
4 usec_timeout=500000 usect_delayed=392000 reason=VMSCAN_THROTTLE_NOPROGRESS
4 usec_timeout=500000 usect_delayed=432000 reason=VMSCAN_THROTTLE_NOPROGRESS
5 usec_timeout=500000 usect_delayed=204000 reason=VMSCAN_THROTTLE_NOPROGRESS
5 usec_timeout=500000 usect_delayed=220000 reason=VMSCAN_THROTTLE_NOPROGRESS
5 usec_timeout=500000 usect_delayed=412000 reason=VMSCAN_THROTTLE_NOPROGRESS
5 usec_timeout=500000 usect_delayed=436000 reason=VMSCAN_THROTTLE_NOPROGRESS
6 usec_timeout=500000 usect_delayed=488000 reason=VMSCAN_THROTTLE_NOPROGRESS
7 usec_timeout=500000 usect_delayed=212000 reason=VMSCAN_THROTTLE_NOPROGRESS
7 usec_timeout=500000 usect_delayed=300000 reason=VMSCAN_THROTTLE_NOPROGRESS
7 usec_timeout=500000 usect_delayed=316000 reason=VMSCAN_THROTTLE_NOPROGRESS
7 usec_timeout=500000 usect_delayed=472000 reason=VMSCAN_THROTTLE_NOPROGRESS
8 usec_timeout=500000 usect_delayed=248000 reason=VMSCAN_THROTTLE_NOPROGRESS
8 usec_timeout=500000 usect_delayed=356000 reason=VMSCAN_THROTTLE_NOPROGRESS
8 usec_timeout=500000 usect_delayed=456000 reason=VMSCAN_THROTTLE_NOPROGRESS
9 usec_timeout=500000 usect_delayed=124000 reason=VMSCAN_THROTTLE_NOPROGRESS
9 usec_timeout=500000 usect_delayed=376000 reason=VMSCAN_THROTTLE_NOPROGRESS
9 usec_timeout=500000 usect_delayed=484000 reason=VMSCAN_THROTTLE_NOPROGRESS
10 usec_timeout=500000 usect_delayed=172000 reason=VMSCAN_THROTTLE_NOPROGRESS
10 usec_timeout=500000 usect_delayed=420000 reason=VMSCAN_THROTTLE_NOPROGRESS
10 usec_timeout=500000 usect_delayed=452000 reason=VMSCAN_THROTTLE_NOPROGRESS
11 usec_timeout=500000 usect_delayed=256000 reason=VMSCAN_THROTTLE_NOPROGRESS
12 usec_timeout=500000 usect_delayed=112000 reason=VMSCAN_THROTTLE_NOPROGRESS
12 usec_timeout=500000 usect_delayed=116000 reason=VMSCAN_THROTTLE_NOPROGRESS
12 usec_timeout=500000 usect_delayed=144000 reason=VMSCAN_THROTTLE_NOPROGRESS
12 usec_timeout=500000 usect_delayed=152000 reason=VMSCAN_THROTTLE_NOPROGRESS
12 usec_timeout=500000 usect_delayed=264000 reason=VMSCAN_THROTTLE_NOPROGRESS
12 usec_timeout=500000 usect_delayed=384000 reason=VMSCAN_THROTTLE_NOPROGRESS
12 usec_timeout=500000 usect_delayed=424000 reason=VMSCAN_THROTTLE_NOPROGRESS
12 usec_timeout=500000 usect_delayed=492000 reason=VMSCAN_THROTTLE_NOPROGRESS
13 usec_timeout=500000 usect_delayed=184000 reason=VMSCAN_THROTTLE_NOPROGRESS
13 usec_timeout=500000 usect_delayed=444000 reason=VMSCAN_THROTTLE_NOPROGRESS
14 usec_timeout=500000 usect_delayed=308000 reason=VMSCAN_THROTTLE_NOPROGRESS
14 usec_timeout=500000 usect_delayed=440000 reason=VMSCAN_THROTTLE_NOPROGRESS
14 usec_timeout=500000 usect_delayed=476000 reason=VMSCAN_THROTTLE_NOPROGRESS
16 usec_timeout=500000 usect_delayed=140000 reason=VMSCAN_THROTTLE_NOPROGRESS
17 usec_timeout=500000 usect_delayed=232000 reason=VMSCAN_THROTTLE_NOPROGRESS
17 usec_timeout=500000 usect_delayed=240000 reason=VMSCAN_THROTTLE_NOPROGRESS
17 usec_timeout=500000 usect_delayed=280000 reason=VMSCAN_THROTTLE_NOPROGRESS
18 usec_timeout=500000 usect_delayed=404000 reason=VMSCAN_THROTTLE_NOPROGRESS
20 usec_timeout=500000 usect_delayed=148000 reason=VMSCAN_THROTTLE_NOPROGRESS
20 usec_timeout=500000 usect_delayed=216000 reason=VMSCAN_THROTTLE_NOPROGRESS
20 usec_timeout=500000 usect_delayed=468000 reason=VMSCAN_THROTTLE_NOPROGRESS
21 usec_timeout=500000 usect_delayed=448000 reason=VMSCAN_THROTTLE_NOPROGRESS
23 usec_timeout=500000 usect_delayed=168000 reason=VMSCAN_THROTTLE_NOPROGRESS
23 usec_timeout=500000 usect_delayed=296000 reason=VMSCAN_THROTTLE_NOPROGRESS
25 usec_timeout=500000 usect_delayed=132000 reason=VMSCAN_THROTTLE_NOPROGRESS
25 usec_timeout=500000 usect_delayed=352000 reason=VMSCAN_THROTTLE_NOPROGRESS
26 usec_timeout=500000 usect_delayed=180000 reason=VMSCAN_THROTTLE_NOPROGRESS
27 usec_timeout=500000 usect_delayed=284000 reason=VMSCAN_THROTTLE_NOPROGRESS
28 usec_timeout=500000 usect_delayed=164000 reason=VMSCAN_THROTTLE_NOPROGRESS
29 usec_timeout=500000 usect_delayed=136000 reason=VMSCAN_THROTTLE_NOPROGRESS
30 usec_timeout=500000 usect_delayed=200000 reason=VMSCAN_THROTTLE_NOPROGRESS
30 usec_timeout=500000 usect_delayed=400000 reason=VMSCAN_THROTTLE_NOPROGRESS
31 usec_timeout=500000 usect_delayed=196000 reason=VMSCAN_THROTTLE_NOPROGRESS
32 usec_timeout=500000 usect_delayed=156000 reason=VMSCAN_THROTTLE_NOPROGRESS
33 usec_timeout=500000 usect_delayed=224000 reason=VMSCAN_THROTTLE_NOPROGRESS
35 usec_timeout=500000 usect_delayed=128000 reason=VMSCAN_THROTTLE_NOPROGRESS
35 usec_timeout=500000 usect_delayed=176000 reason=VMSCAN_THROTTLE_NOPROGRESS
36 usec_timeout=500000 usect_delayed=368000 reason=VMSCAN_THROTTLE_NOPROGRESS
36 usec_timeout=500000 usect_delayed=496000 reason=VMSCAN_THROTTLE_NOPROGRESS
37 usec_timeout=500000 usect_delayed=312000 reason=VMSCAN_THROTTLE_NOPROGRESS
38 usec_timeout=500000 usect_delayed=304000 reason=VMSCAN_THROTTLE_NOPROGRESS
40 usec_timeout=500000 usect_delayed=288000 reason=VMSCAN_THROTTLE_NOPROGRESS
43 usec_timeout=500000 usect_delayed=408000 reason=VMSCAN_THROTTLE_NOPROGRESS
55 usec_timeout=500000 usect_delayed=416000 reason=VMSCAN_THROTTLE_NOPROGRESS
56 usec_timeout=500000 usect_delayed=76000 reason=VMSCAN_THROTTLE_NOPROGRESS
58 usec_timeout=500000 usect_delayed=120000 reason=VMSCAN_THROTTLE_NOPROGRESS
59 usec_timeout=500000 usect_delayed=208000 reason=VMSCAN_THROTTLE_NOPROGRESS
61 usec_timeout=500000 usect_delayed=68000 reason=VMSCAN_THROTTLE_NOPROGRESS
71 usec_timeout=500000 usect_delayed=192000 reason=VMSCAN_THROTTLE_NOPROGRESS
71 usec_timeout=500000 usect_delayed=480000 reason=VMSCAN_THROTTLE_NOPROGRESS
79 usec_timeout=500000 usect_delayed=60000 reason=VMSCAN_THROTTLE_NOPROGRESS
82 usec_timeout=500000 usect_delayed=320000 reason=VMSCAN_THROTTLE_NOPROGRESS
82 usec_timeout=500000 usect_delayed=92000 reason=VMSCAN_THROTTLE_NOPROGRESS
85 usec_timeout=500000 usect_delayed=64000 reason=VMSCAN_THROTTLE_NOPROGRESS
85 usec_timeout=500000 usect_delayed=80000 reason=VMSCAN_THROTTLE_NOPROGRESS
88 usec_timeout=500000 usect_delayed=84000 reason=VMSCAN_THROTTLE_NOPROGRESS
90 usec_timeout=500000 usect_delayed=160000 reason=VMSCAN_THROTTLE_NOPROGRESS
90 usec_timeout=500000 usect_delayed=292000 reason=VMSCAN_THROTTLE_NOPROGRESS
94 usec_timeout=500000 usect_delayed=56000 reason=VMSCAN_THROTTLE_NOPROGRESS
118 usec_timeout=500000 usect_delayed=88000 reason=VMSCAN_THROTTLE_NOPROGRESS
119 usec_timeout=500000 usect_delayed=72000 reason=VMSCAN_THROTTLE_NOPROGRESS
126 usec_timeout=500000 usect_delayed=108000 reason=VMSCAN_THROTTLE_NOPROGRESS
146 usec_timeout=500000 usect_delayed=52000 reason=VMSCAN_THROTTLE_NOPROGRESS
148 usec_timeout=500000 usect_delayed=36000 reason=VMSCAN_THROTTLE_NOPROGRESS
148 usec_timeout=500000 usect_delayed=48000 reason=VMSCAN_THROTTLE_NOPROGRESS
159 usec_timeout=500000 usect_delayed=28000 reason=VMSCAN_THROTTLE_NOPROGRESS
178 usec_timeout=500000 usect_delayed=44000 reason=VMSCAN_THROTTLE_NOPROGRESS
183 usec_timeout=500000 usect_delayed=40000 reason=VMSCAN_THROTTLE_NOPROGRESS
237 usec_timeout=500000 usect_delayed=100000 reason=VMSCAN_THROTTLE_NOPROGRESS
266 usec_timeout=500000 usect_delayed=32000 reason=VMSCAN_THROTTLE_NOPROGRESS
313 usec_timeout=500000 usect_delayed=24000 reason=VMSCAN_THROTTLE_NOPROGRESS
347 usec_timeout=500000 usect_delayed=96000 reason=VMSCAN_THROTTLE_NOPROGRESS
470 usec_timeout=500000 usect_delayed=20000 reason=VMSCAN_THROTTLE_NOPROGRESS
559 usec_timeout=500000 usect_delayed=16000 reason=VMSCAN_THROTTLE_NOPROGRESS
964 usec_timeout=500000 usect_delayed=12000 reason=VMSCAN_THROTTLE_NOPROGRESS
2001 usec_timeout=500000 usect_delayed=104000 reason=VMSCAN_THROTTLE_NOPROGRESS
2447 usec_timeout=500000 usect_delayed=8000 reason=VMSCAN_THROTTLE_NOPROGRESS
7888 usec_timeout=500000 usect_delayed=4000 reason=VMSCAN_THROTTLE_NOPROGRESS
22727 usec_timeout=500000 usect_delayed=0 reason=VMSCAN_THROTTLE_NOPROGRESS
51305 usec_timeout=500000 usect_delayed=500000 reason=VMSCAN_THROTTLE_NOPROGRESS
The full timeout is often hit but a large number also do not stall at
all. The remainder slept a little allowing other reclaim tasks to make
progress.
While this timeout could be further increased, it could also negatively
impact worst-case behaviour when there is no prioritisation of what task
should make progress.
For VMSCAN_THROTTLE_WRITEBACK, the breakdown was
1 usec_timeout=100000 usect_delayed=44000 reason=VMSCAN_THROTTLE_WRITEBACK
2 usec_timeout=100000 usect_delayed=76000 reason=VMSCAN_THROTTLE_WRITEBACK
3 usec_timeout=100000 usect_delayed=80000 reason=VMSCAN_THROTTLE_WRITEBACK
5 usec_timeout=100000 usect_delayed=48000 reason=VMSCAN_THROTTLE_WRITEBACK
5 usec_timeout=100000 usect_delayed=84000 reason=VMSCAN_THROTTLE_WRITEBACK
6 usec_timeout=100000 usect_delayed=72000 reason=VMSCAN_THROTTLE_WRITEBACK
7 usec_timeout=100000 usect_delayed=88000 reason=VMSCAN_THROTTLE_WRITEBACK
11 usec_timeout=100000 usect_delayed=56000 reason=VMSCAN_THROTTLE_WRITEBACK
12 usec_timeout=100000 usect_delayed=64000 reason=VMSCAN_THROTTLE_WRITEBACK
16 usec_timeout=100000 usect_delayed=92000 reason=VMSCAN_THROTTLE_WRITEBACK
24 usec_timeout=100000 usect_delayed=68000 reason=VMSCAN_THROTTLE_WRITEBACK
28 usec_timeout=100000 usect_delayed=32000 reason=VMSCAN_THROTTLE_WRITEBACK
30 usec_timeout=100000 usect_delayed=60000 reason=VMSCAN_THROTTLE_WRITEBACK
30 usec_timeout=100000 usect_delayed=96000 reason=VMSCAN_THROTTLE_WRITEBACK
32 usec_timeout=100000 usect_delayed=52000 reason=VMSCAN_THROTTLE_WRITEBACK
42 usec_timeout=100000 usect_delayed=40000 reason=VMSCAN_THROTTLE_WRITEBACK
77 usec_timeout=100000 usect_delayed=28000 reason=VMSCAN_THROTTLE_WRITEBACK
99 usec_timeout=100000 usect_delayed=36000 reason=VMSCAN_THROTTLE_WRITEBACK
137 usec_timeout=100000 usect_delayed=24000 reason=VMSCAN_THROTTLE_WRITEBACK
190 usec_timeout=100000 usect_delayed=20000 reason=VMSCAN_THROTTLE_WRITEBACK
339 usec_timeout=100000 usect_delayed=16000 reason=VMSCAN_THROTTLE_WRITEBACK
518 usec_timeout=100000 usect_delayed=12000 reason=VMSCAN_THROTTLE_WRITEBACK
852 usec_timeout=100000 usect_delayed=8000 reason=VMSCAN_THROTTLE_WRITEBACK
3359 usec_timeout=100000 usect_delayed=4000 reason=VMSCAN_THROTTLE_WRITEBACK
7147 usec_timeout=100000 usect_delayed=0 reason=VMSCAN_THROTTLE_WRITEBACK
83962 usec_timeout=100000 usect_delayed=100000 reason=VMSCAN_THROTTLE_WRITEBACK
The majority hit the timeout in direct reclaim context although a
sizable number did not stall at all. This is very different to kswapd
where only a tiny percentage of stalls due to writeback reached the
timeout.
Bottom line, the throttling appears to work and the wakeup events may
limit worst case stalls. There might be some grounds for adjusting
timeouts but it's likely futile as the worst-case scenarios depend on
the workload, memory size and the speed of the storage. A better
approach to improve the series further would be to prioritise tasks
based on their rate of allocation with the caveat that it may be very
expensive to track.
This patch (of 5):
Page reclaim throttles on wait_iff_congested under the following
conditions:
- kswapd is encountering pages under writeback and marked for immediate
reclaim implying that pages are cycling through the LRU faster than
pages can be cleaned.
- Direct reclaim will stall if all dirty pages are backed by congested
inodes.
wait_iff_congested is almost completely broken with few exceptions.
This patch adds a new node-based workqueue and tracks the number of
throttled tasks and pages written back since throttling started. If
enough pages belonging to the node are written back then the throttled
tasks will wake early. If not, the throttled tasks sleeps until the
timeout expires.
[neilb@suse.de: Uninterruptible sleep and simpler wakeups]
[hdanton@sina.com: Avoid race when reclaim starts]
[vbabka@suse.cz: vmstat irq-safe api, clarifications]
Link: https://lore.kernel.org/linux-mm/45d8b7a6-8548-65f5-cccf-9f451d4ae3d4@kernel.dk/ [1]
Link: https://lkml.kernel.org/r/20211022144651.19914-1-mgorman@techsingularity.net
Link: https://lkml.kernel.org/r/20211022144651.19914-2-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: NeilBrown <neilb@suse.de>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: "Darrick J . Wong" <djwong@kernel.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We fix the following warning when building kernel with W=1:
mm/vmscan.c:1362:6: warning: variable 'err' set but not used [-Wunused-but-set-variable]
Link: https://lkml.kernel.org/r/20210924181218.21165-1-songkai01@inspur.com
Signed-off-by: Kai Song <songkai01@inspur.com>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
core:
- improve dma_fence, lease and resv documentation
- shmem-helpers: allocate WC pages on x86, use vmf_insert_pin
- sched fixes/improvements
- allow empty drm leases
- add dma resv iterator
- add more DP 2.0 headers
- DP MST helper improvements for DP2.0
dma-buf:
- avoid warnings, remove fence trace macros
bridge:
- new helper to get rid of panels
- probe improvements for it66121
- enable DSI EOTP for anx7625
fbdev:
- efifb: release runtime PM on destroy
ttm:
- kerneldoc switch
- helper to clear all DMA mappings
- pool shrinker optimizaton
- remove ttm_tt_destroy_common
- update ttm_move_memcpy for async use
panel:
- add new panel-edp driver
amdgpu:
- Initial DP 2.0 support
- Initial USB4 DP tunnelling support
- Aldebaran MCE support
- Modifier support for DCC image stores for GFX 10.3
- Display rework for better FP code handling
- Yellow Carp/Cyan Skillfish updates
- Cyan Skillfish display support
- convert vega/navi to IP discovery asic enumeration
- validate IP discovery table
- RAS improvements
- Lots of fixes
i915:
- DG1 PCI IDs + LMEM discovery/placement
- DG1 GuC submission by default
- ADL-S PCI IDs updated + enabled by default
- ADL-P (XE_LPD) fixed and updates
- DG2 display fixes
- PXP protected object support for Gen12 integrated
- expose multi-LRC submission interface for GuC
- export logical engine instance to user
- Disable engine bonding on Gen12+
- PSR cleanup
- PSR2 selective fetch by default
- DP 2.0 prep work
- VESA vendor block + MSO use of it
- FBC refactor
- try again to fix fast-narrow vs slow-wide eDP training
- use THP when IOMMU enabled
- LMEM backup/restore for suspend/resume
- locking simplification
- GuC major reworking
- async flip VT-D workaround changes
- DP link training improvements
- misc display refactorings
bochs:
- new PCI ID
rcar-du:
- Non-contiguious buffer import support for rcar-du
- r8a779a0 support prep
omapdrm:
- COMPILE_TEST fixes
sti:
- COMPILE_TEST fixes
msm:
- fence ordering improvements
- eDP support in DP sub-driver
- dpu irq handling cleanup
- CRC support for making igt happy
- NO_CONNECTOR bridge support
- dsi: 14nm phy support for msm8953
- mdp5: msm8x53, sdm450, sdm632 support
stm:
- layer alpha + zpo support
v3d:
- fix Vulkan CTS failure
- support multiple sync objects
gud:
- add R8/RGB332/RGB888 pixel formats
vc4:
- convert to new bridge helpers
vgem:
- use shmem helpers
virtio:
- support mapping exported vram
zte:
- remove obsolete driver
rockchip:
- use bridge attach no connector for LVDS/RGB
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Merge tag 'drm-next-2021-11-03' of git://anongit.freedesktop.org/drm/drm
Pull drm updates from Dave Airlie:
"Summary below. i915 starts to add support for DG2 GPUs, enables DG1
and ADL-S support by default, lots of work to enable DisplayPort 2.0
across drivers. Lots of documentation updates and fixes across the
board.
core:
- improve dma_fence, lease and resv documentation
- shmem-helpers: allocate WC pages on x86, use vmf_insert_pin
- sched fixes/improvements
- allow empty drm leases
- add dma resv iterator
- add more DP 2.0 headers
- DP MST helper improvements for DP2.0
dma-buf:
- avoid warnings, remove fence trace macros
bridge:
- new helper to get rid of panels
- probe improvements for it66121
- enable DSI EOTP for anx7625
fbdev:
- efifb: release runtime PM on destroy
ttm:
- kerneldoc switch
- helper to clear all DMA mappings
- pool shrinker optimizaton
- remove ttm_tt_destroy_common
- update ttm_move_memcpy for async use
panel:
- add new panel-edp driver
amdgpu:
- Initial DP 2.0 support
- Initial USB4 DP tunnelling support
- Aldebaran MCE support
- Modifier support for DCC image stores for GFX 10.3
- Display rework for better FP code handling
- Yellow Carp/Cyan Skillfish updates
- Cyan Skillfish display support
- convert vega/navi to IP discovery asic enumeration
- validate IP discovery table
- RAS improvements
- Lots of fixes
i915:
- DG1 PCI IDs + LMEM discovery/placement
- DG1 GuC submission by default
- ADL-S PCI IDs updated + enabled by default
- ADL-P (XE_LPD) fixed and updates
- DG2 display fixes
- PXP protected object support for Gen12 integrated
- expose multi-LRC submission interface for GuC
- export logical engine instance to user
- Disable engine bonding on Gen12+
- PSR cleanup
- PSR2 selective fetch by default
- DP 2.0 prep work
- VESA vendor block + MSO use of it
- FBC refactor
- try again to fix fast-narrow vs slow-wide eDP training
- use THP when IOMMU enabled
- LMEM backup/restore for suspend/resume
- locking simplification
- GuC major reworking
- async flip VT-D workaround changes
- DP link training improvements
- misc display refactorings
bochs:
- new PCI ID
rcar-du:
- Non-contiguious buffer import support for rcar-du
- r8a779a0 support prep
omapdrm:
- COMPILE_TEST fixes
sti:
- COMPILE_TEST fixes
msm:
- fence ordering improvements
- eDP support in DP sub-driver
- dpu irq handling cleanup
- CRC support for making igt happy
- NO_CONNECTOR bridge support
- dsi: 14nm phy support for msm8953
- mdp5: msm8x53, sdm450, sdm632 support
stm:
- layer alpha + zpo support
v3d:
- fix Vulkan CTS failure
- support multiple sync objects
gud:
- add R8/RGB332/RGB888 pixel formats
vc4:
- convert to new bridge helpers
vgem:
- use shmem helpers
virtio:
- support mapping exported vram
zte:
- remove obsolete driver
rockchip:
- use bridge attach no connector for LVDS/RGB"
* tag 'drm-next-2021-11-03' of git://anongit.freedesktop.org/drm/drm: (1259 commits)
drm/amdgpu/gmc6: fix DMA mask from 44 to 40 bits
drm/amd/display: MST support for DPIA
drm/amdgpu: Fix even more out of bound writes from debugfs
drm/amdgpu/discovery: add SDMA IP instance info for soc15 parts
drm/amdgpu/discovery: add UVD/VCN IP instance info for soc15 parts
drm/amdgpu/UAPI: rearrange header to better align related items
drm/amd/display: Enable dpia in dmub only for DCN31 B0
drm/amd/display: Fix USB4 hot plug crash issue
drm/amd/display: Fix deadlock when falling back to v2 from v3
drm/amd/display: Fallback to clocks which meet requested voltage on DCN31
drm/amd/display: move FPU associated DCN301 code to DML folder
drm/amd/display: fix link training regression for 1 or 2 lane
drm/amd/display: add two lane settings training options
drm/amd/display: decouple hw_lane_settings from dpcd_lane_settings
drm/amd/display: implement decide lane settings
drm/amd/display: adopt DP2.0 LT SCR revision 8
drm/amd/display: FEC configuration for dpia links in MST mode
drm/amd/display: FEC configuration for dpia links
drm/amd/display: Add workaround flag for EDID read on certain docks
drm/amd/display: Set phy_mux_sel bit in dmub scratch register
...
These are the folio equivalents of relock_page_lruvec_irq() and
folio_lruvec_relock_irqsave(). Also convert page_matches_lruvec()
to folio_matches_lruvec().
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
These are the folio equivalents of lock_page_lruvec() and similar
functions. Also convert lruvec_memcg_debug() to take a folio.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Commit f56ce412a5 ("mm: memcontrol: fix occasional OOMs due to
proportional memory.low reclaim") introduced a divide by zero corner
case when oomd is being used in combination with cgroup memory.low
protection.
When oomd decides to kill a cgroup, it will force the cgroup memory to
be reclaimed after killing the tasks, by writing to the memory.max file
for that cgroup, forcing the remaining page cache and reclaimable slab
to be reclaimed down to zero.
Previously, on cgroups with some memory.low protection that would result
in the memory being reclaimed down to the memory.low limit, or likely
not at all, having the page cache reclaimed asynchronously later.
With f56ce412a5 the oomd write to memory.max tries to reclaim all the
way down to zero, which may race with another reclaimer, to the point of
ending up with the divide by zero below.
This patch implements the obvious fix.
Link: https://lkml.kernel.org/r/20210826220149.058089c6@imladris.surriel.com
Fixes: f56ce412a5 ("mm: memcontrol: fix occasional OOMs due to proportional memory.low reclaim")
Signed-off-by: Rik van Riel <riel@surriel.com>
Acked-by: Roman Gushchin <guro@fb.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Chris Down <chris@chrisdown.name>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
drop_slab_node() is called as part of echo 2>/proc/sys/vm/drop_caches
operation. It iterates over all memcgs and calls shrink_slab() which in
turn iterates over all slab shrinkers. Freed objects are counted and as
long as the total number of freed objects from all memcgs and shrinkers is
higher than 10, drop_slab_node() loops for another full memcgs*shrinkers
iteration.
This arbitrary constant threshold of 10 can result in effectively an
infinite loop on a system with large number of memcgs and/or parallel
activity that allocates new objects. This has been reported previously by
Chunxin Zang [1] and recently by our customer.
The previous report [1] has resulted in commit 069c411de4 ("mm/vmscan:
fix infinite loop in drop_slab_node") which added a check for signals
allowing the user to terminate the command writing to drop_caches. At the
time it was also considered to make the threshold grow with each iteration
to guarantee termination, but such patch hasn't been formally proposed
yet.
This patch implements the dynamically growing threshold. At first
iteration it's enough to free one object to continue, and this threshold
effectively doubles with each iteration. Our customer's feedback was
positive.
There is always a risk that this change will result on some system in a
previously terminating drop_caches operation to terminate sooner and free
fewer objects. Ideally the semantics would guarantee freeing all freeable
objects that existed at the moment of starting the operation, while not
looping forever for newly allocated objects, but that's not feasible to
track. In the less ideal solution based on thresholds, arguably the
termination guarantee is more important than the exhaustiveness guarantee.
If there are reports of large regression wrt being exhaustive, we can
tune how fast the threshold grows.
[1] https://lore.kernel.org/lkml/20200909152047.27905-1-zangchunxin@bytedance.com/T/#u
[vbabka@suse.cz: avoid undefined shift behaviour]
Link: https://lkml.kernel.org/r/2f034e6f-a753-550a-f374-e4e23899d3d5@suse.cz
Link: https://lkml.kernel.org/r/20210818152239.25502-1-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Reported-by: Chunxin Zang <zangchunxin@bytedance.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Chris Down <chris@chrisdown.name>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We could add 'else' to remove the somewhat odd check_pending label to make
code core succinct.
Link: https://lkml.kernel.org/r/20210717065911.61497-5-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Alex Shi <alexs@kernel.org>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Shaohua Li <shli@fb.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The return value of kswapd_run() is unused now. Clean it up.
Link: https://lkml.kernel.org/r/20210717065911.61497-4-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Alex Shi <alexs@kernel.org>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Shaohua Li <shli@fb.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The priority field of sc is used to control how many pages we should scan
at once while we always traverse the list to shrink the pages in these
functions. So these settings are unneeded and misleading.
Link: https://lkml.kernel.org/r/20210717065911.61497-3-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: Alex Shi <alexs@kernel.org>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Shaohua Li <shli@fb.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "Cleanups for vmscan", v2.
This series contains cleanups to remove unneeded return value, misleading
setting and so on. Also this remove the PageDirty check after MADV_FREE
pages are page_ref_freezed. More details can be found in the respective
changelogs.
This patch (of 4):
If the MADV_FREE pages are redirtied before they could be reclaimed, put
the pages back to anonymous LRU list by setting SwapBacked flag and the
pages will be reclaimed in normal swapout way. But as Yu Zhao pointed
out, "The page has only one reference left, which is from the isolation.
After the caller puts the page back on lru and drops the reference, the
page will be freed anyway. It doesn't matter which lru it goes." So we
don't bother checking PageDirty here.
[Yu Zhao's comment is also quoted in the code.]
Link: https://lkml.kernel.org/r/20210717065911.61497-1-linmiaohe@huawei.com
Link: https://lkml.kernel.org/r/20210717065911.61497-2-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Yu Zhao <yuzhao@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Alex Shi <alexs@kernel.org>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Shaohua Li <shli@fb.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Some method is obviously needed to enable reclaim-based migration.
Just like traditional autonuma, there will be some workloads that will
benefit like workloads with more "static" configurations where hot pages
stay hot and cold pages stay cold. If pages come and go from the hot and
cold sets, the benefits of this approach will be more limited.
The benefits are truly workload-based and *not* hardware-based. We do not
believe that there is a viable threshold where certain hardware
configurations should have this mechanism enabled while others do not.
To be conservative, earlier work defaulted to disable reclaim- based
migration and did not include a mechanism to enable it. This proposes add
a new sysfs file
/sys/kernel/mm/numa/demotion_enabled
as a method to enable it.
We are open to any alternative that allows end users to enable this
mechanism or disable it if workload harm is detected (just like
traditional autonuma).
Once this is enabled page demotion may move data to a NUMA node that does
not fall into the cpuset of the allocating process. This could be
construed to violate the guarantees of cpusets. However, since this is an
opt-in mechanism, the assumption is that anyone enabling it is content to
relax the guarantees.
Link: https://lkml.kernel.org/r/20210721063926.3024591-9-ying.huang@intel.com
Link: https://lkml.kernel.org/r/20210715055145.195411-10-ying.huang@intel.com
Signed-off-by: Huang Ying <ying.huang@intel.com>
Originally-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Wei Xu <weixugc@google.com>
Cc: Yang Shi <yang.shi@linux.alibaba.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Keith Busch <kbusch@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Global reclaim aims to reduce the amount of memory used on a given node or
set of nodes. Migrating pages to another node serves this purpose.
memcg reclaim is different. Its goal is to reduce the total memory
consumption of the entire memcg, across all nodes. Migration does not
assist memcg reclaim because it just moves page contents between nodes
rather than actually reducing memory consumption.
Link: https://lkml.kernel.org/r/20210715055145.195411-9-ying.huang@intel.com
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Suggested-by: Yang Shi <yang.shi@linux.alibaba.com>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Wei Xu <weixugc@google.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: David Rientjes <rientjes@google.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Keith Busch <kbusch@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Reclaim anonymous pages if a migration path is available now that demotion
provides a non-swap recourse for reclaiming anon pages.
Note that this check is subtly different from the can_age_anon_pages()
checks. This mechanism checks whether a specific page in a specific
context can actually be reclaimed, given current swap space and cgroup
limits.
can_age_anon_pages() is a much simpler and more preliminary check which
just says whether there is a possibility of future reclaim.
[kbusch@kernel.org: v11]
Link: https://lkml.kernel.org/r/20210715055145.195411-8-ying.huang@intel.com
Link: https://lkml.kernel.org/r/20210721063926.3024591-7-ying.huang@intel.com
Link: https://lkml.kernel.org/r/20210715055145.195411-8-ying.huang@intel.com
Cc: Keith Busch <kbusch@kernel.org>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Wei Xu <weixugc@google.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Yang Shi <yang.shi@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Anonymous pages are kept on their own LRU(s). These lists could
theoretically always be scanned and maintained. But, without swap, there
is currently nothing the kernel can *do* with the results of a scanned,
sorted LRU for anonymous pages.
A check for '!total_swap_pages' currently serves as a valid check as to
whether anonymous LRUs should be maintained. However, another method will
be added shortly: page demotion.
Abstract out the 'total_swap_pages' checks into a helper, give it a
logically significant name, and check for the possibility of page
demotion.
[dave.hansen@linux.intel.com: v11]
Link: https://lkml.kernel.org/r/20210715055145.195411-7-ying.huang@intel.com
Link: https://lkml.kernel.org/r/20210721063926.3024591-6-ying.huang@intel.com
Link: https://lkml.kernel.org/r/20210715055145.195411-7-ying.huang@intel.com
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Reviewed-by: Greg Thelen <gthelen@google.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Wei Xu <weixugc@google.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: David Rientjes <rientjes@google.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Keith Busch <kbusch@kernel.org>
Cc: Yang Shi <yang.shi@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Account the number of demoted pages.
Add pgdemote_kswapd and pgdemote_direct VM counters showed in
/proc/vmstat.
[ daveh:
- __count_vm_events() a bit, and made them look at the THP
size directly rather than getting data from migrate_pages()
]
Link: https://lkml.kernel.org/r/20210721063926.3024591-5-ying.huang@intel.com
Link: https://lkml.kernel.org/r/20210715055145.195411-6-ying.huang@intel.com
Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Reviewed-by: Wei Xu <weixugc@google.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Greg Thelen <gthelen@google.com>
Cc: Keith Busch <kbusch@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This is mostly derived from a patch from Yang Shi:
https://lore.kernel.org/linux-mm/1560468577-101178-10-git-send-email-yang.shi@linux.alibaba.com/
Add code to the reclaim path (shrink_page_list()) to "demote" data to
another NUMA node instead of discarding the data. This always avoids the
cost of I/O needed to read the page back in and sometimes avoids the
writeout cost when the page is dirty.
A second pass through shrink_page_list() will be made if any demotions
fail. This essentially falls back to normal reclaim behavior in the case
that demotions fail. Previous versions of this patch may have simply
failed to reclaim pages which were eligible for demotion but were unable
to be demoted in practice.
For some cases, for example, MADV_PAGEOUT, the pages are always discarded
instead of demoted to follow the kernel API definition. Because
MADV_PAGEOUT is defined as freeing specified pages regardless in which
tier they are.
Note: This just adds the start of infrastructure for migration. It is
actually disabled next to the FIXME in migrate_demote_page_ok().
[dave.hansen@linux.intel.com: v11]
Link: https://lkml.kernel.org/r/20210715055145.195411-5-ying.huang@intel.com
Link: https://lkml.kernel.org/r/20210721063926.3024591-4-ying.huang@intel.com
Link: https://lkml.kernel.org/r/20210715055145.195411-5-ying.huang@intel.com
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Reviewed-by: Wei Xu <weixugc@google.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Keith Busch <kbusch@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
At the moment memcg stats are read in four contexts:
1. memcg stat user interfaces
2. dirty throttling
3. page fault
4. memory reclaim
Currently the kernel flushes the stats for first two cases. Flushing the
stats for remaining two casese may have performance impact. Always
flushing the memcg stats on the page fault code path may negatively
impacts the performance of the applications. In addition flushing in the
memory reclaim code path, though treated as slowpath, can become the
source of contention for the global lock taken for stat flushing because
when system or memcg is under memory pressure, many tasks may enter the
reclaim path.
This patch uses following mechanisms to solve these challenges:
1. Periodically flush the stats from root memcg every 2 seconds. This
will time limit the out of sync stats.
2. Asynchronously flush the stats after fixed number of stat updates.
In the worst case the stat can be out of sync by O(nr_cpus * BATCH) for
2 seconds.
3. For avoiding thundering herd to flush the stats particularly from
the memory reclaim context, introduce memcg local spinlock and let only
one flusher active at a time. This could have been done through
cgroup_rstat_lock lock but that lock is used by other subsystem and for
userspace reading memcg stats. So, it is better to keep flushers
introduced by this patch decoupled from cgroup_rstat_lock. However we
would have to use irqsafe version of rstat flush but that is fine as
this code path will be flushing for whole tree and do the work for
everyone. No one will be waiting for that worker.
[shakeelb@google.com: fix sleep-in-wrong context bug]
Link: https://lkml.kernel.org/r/20210716212137.1391164-2-shakeelb@google.com
Link: https://lkml.kernel.org/r/20210714013948.270662-2-shakeelb@google.com
Signed-off-by: Shakeel Butt <shakeelb@google.com>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Michal Koutný <mkoutny@suse.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The page cache deletion paths all have interrupts enabled, so no need to
use irqsafe/irqrestore locking variants.
They used to have irqs disabled by the memcg lock added in commit
c4843a7593 ("memcg: add per cgroup dirty page accounting"), but that has
since been replaced by memcg taking the page lock instead, commit
0a31bc97c8 ("mm: memcontrol: rewrite uncharge AP").
Link: https://lkml.kernel.org/r/20210614211904.14420-1-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
A recent lockdep report included these lines:
[ 96.177910] 3 locks held by containerd/770:
[ 96.177934] #0: ffff88810815ea28 (&mm->mmap_lock#2){++++}-{3:3},
at: do_user_addr_fault+0x115/0x770
[ 96.177999] #1: ffffffff82915020 (rcu_read_lock){....}-{1:2}, at:
get_swap_device+0x33/0x140
[ 96.178057] #2: ffffffff82955ba0 (fs_reclaim){+.+.}-{0:0}, at:
__fs_reclaim_acquire+0x5/0x30
While it was not useful to that bug report to know where the reclaim lock
had been acquired, it might be useful under other circumstances. Allow
the caller of __fs_reclaim_acquire to specify the instruction pointer to
use.
Link: https://lkml.kernel.org/r/20210719185709.1755149-1-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Omar Sandoval <osandov@fb.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
While unplugging a device the TTM shrinker implementation
needs a barrier to make sure that all concurrent shrink
operations are done and no other CPU is referring to a
device specific pool any more.
Taking and releasing the shrinker semaphore on the write
side after unmapping and freeing all pages from the device
pool should make sure that no shrinker is running in
paralell.
This allows us to avoid the contented mutex in the TTM pool
implementation for every alloc/free operation.
v2: rework the commit message to make clear why we need this
v3: rename the function and add more doc as suggested by Daniel
Signed-off-by: Christian König <christian.koenig@amd.com>
Acked-by: Huang Rui <ray.huang@amd.com>
Acked-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20210820120528.81114-2-christian.koenig@amd.com
In a debugging session the other day, Rik noticed that node_reclaim()
was missing memstall annotations. This means we'll miss pressure and
lost productivity resulting from reclaim on an overloaded local NUMA
node when vm.zone_reclaim_mode is enabled.
There haven't been any reports, but that's likely because
vm.zone_reclaim_mode hasn't been a commonly used feature recently, and
the intersection between such setups and psi users is probably nil.
But secondary memory such as CXL-connected DIMMS, persistent memory etc,
and the page demotion patches that handle them
(https://lore.kernel.org/lkml/20210401183216.443C4443@viggo.jf.intel.com/)
could soon make this a more common codepath again.
Link: https://lkml.kernel.org/r/20210818152457.35846-1-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reported-by: Rik van Riel <riel@surriel.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We've noticed occasional OOM killing when memory.low settings are in
effect for cgroups. This is unexpected and undesirable as memory.low is
supposed to express non-OOMing memory priorities between cgroups.
The reason for this is proportional memory.low reclaim. When cgroups
are below their memory.low threshold, reclaim passes them over in the
first round, and then retries if it couldn't find pages anywhere else.
But when cgroups are slightly above their memory.low setting, page scan
force is scaled down and diminished in proportion to the overage, to the
point where it can cause reclaim to fail as well - only in that case we
currently don't retry, and instead trigger OOM.
To fix this, hook proportional reclaim into the same retry logic we have
in place for when cgroups are skipped entirely. This way if reclaim
fails and some cgroups were scanned with diminished pressure, we'll try
another full-force cycle before giving up and OOMing.
[akpm@linux-foundation.org: coding-style fixes]
Link: https://lkml.kernel.org/r/20210817180506.220056-1-hannes@cmpxchg.org
Fixes: 9783aa9917 ("mm, memcg: proportional memory.{low,min} reclaim")
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reported-by: Leon Yang <lnyng@fb.com>
Reviewed-by: Rik van Riel <riel@surriel.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Roman Gushchin <guro@fb.com>
Acked-by: Chris Down <chris@chrisdown.name>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: <stable@vger.kernel.org> [5.4+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "Clean W=1 build warnings for mm/".
This is a janitorial only. During development of a tool to catch build
warnings early to avoid tripping the Intel lkp-robot, I noticed that mm/
is not clean for W=1. This is generally harmless but there is no harm in
cleaning it up. It disrupts git blame a little but on relatively obvious
lines that are unlikely to be git blame targets.
This patch (of 13):
make W=1 generates the following warning for vmscan.c
mm/vmscan.c:1814: warning: This comment starts with '/**', but isn't a kernel-doc comment. Refer Documentation/doc-guide/kernel-doc.rst
It is not a kerneldoc comment and isolate_lru_pages() is a static
function. While the detailed comment is nice, it does not need to be
exposed via kernel-doc.
Link: https://lkml.kernel.org/r/20210520084809.8576-1-mgorman@techsingularity.net
Link: https://lkml.kernel.org/r/20210520084809.8576-2-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Dan Streetman <ddstreet@ieee.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently try_to_unmap() return bool value by checking page_mapcount(),
however this may return false positive since page_mapcount() doesn't check
all subpages of compound page. The total_mapcount() could be used
instead, but its cost is higher since it traverses all subpages.
Actually the most callers of try_to_unmap() don't care about the return
value at all. So just need check if page is still mapped by page_mapped()
when necessary. And page_mapped() does bail out early when it finds
mapped subpage.
Link: https://lkml.kernel.org/r/bb27e3fe-6036-b637-5086-272befbfe3da@google.com
Suggested-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Yang Shi <shy828301@gmail.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jue Wang <juew@google.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Peter Xu <peterx@redhat.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Wang Yugui <wangyugui@e16-tech.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Theoretically without the protect from memalloc_noreclaim_save() and
memalloc_noreclaim_restore(), reclaim_pages() can go into the block
I/O layer recursively and deadlock.
Querying 'reclaim_pages' in our kernel crash databases didn't yield
any results. So the deadlock seems unlikely to happen. A possible
explanation is that the only user of reclaim_pages(), i.e.,
MADV_PAGEOUT, is usually called before memory pressure builds up,
e.g., on Android and Chrome OS. Under such a condition, allocations in
the block I/O layer can be fulfilled without diverting to direct
reclaim and therefore the recursion is avoided.
Link: https://lkml.kernel.org/r/20210622074642.785473-1-yuzhao@google.com
Link: https://lkml.kernel.org/r/20210614194727.2684053-1-yuzhao@google.com
Signed-off-by: Yu Zhao <yuzhao@google.com>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When kswapd is active then direct reclaim is potentially active. In
either case, it is possible that a zone would be balanced if pages were
not trapped on PCP lists. Instead of draining remote pages, simply limit
the size of the PCP lists while kswapd is active.
Link: https://lkml.kernel.org/r/20210525080119.5455-6-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The noinline_for_stack is introduced by commit 666356297e ("vmscan: set
up pagevec as late as possible in shrink_inactive_list()"), its purpose is
to delay the allocation of pagevec as late as possible to save stack
memory. But the commit 2bcf887963 ("mm: take pagevecs off reclaim
stack") replace pagevecs by lists of pages_to_free. So we do not need
noinline_for_stack, just remove it (let the compiler decide whether to
inline).
Link: https://lkml.kernel.org/r/20210417043538.9793-9-songmuchun@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Roman Gushchin <guro@fb.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Xiongchun Duan <duanxiongchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
lruvec_holds_page_lru_lock() doesn't check anything about locking and is
used to check whether the page belongs to the lruvec. So rename it to
page_matches_lruvec().
Link: https://lkml.kernel.org/r/20210417043538.9793-6-songmuchun@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Xiongchun Duan <duanxiongchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The number of deferred objects might get windup to an absurd number, and
it results in clamp of slab objects. It is undesirable for sustaining
workingset.
So shrink deferred objects proportional to priority and cap nr_deferred
to twice of cache items.
The idea is borrowed from Dave Chinner's patch:
https://lore.kernel.org/linux-xfs/20191031234618.15403-13-david@fromorbit.com/
Tested with kernel build and vfs metadata heavy workload in our
production environment, no regression is spotted so far.
Link: https://lkml.kernel.org/r/20210311190845.9708-14-shy828301@gmail.com
Signed-off-by: Yang Shi <shy828301@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Now shrinker's nr_deferred is per memcg for memcg aware shrinkers, add
to parent's corresponding nr_deferred when memcg offline.
Link: https://lkml.kernel.org/r/20210311190845.9708-13-shy828301@gmail.com
Signed-off-by: Yang Shi <shy828301@gmail.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Acked-by: Roman Gushchin <guro@fb.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Now nr_deferred is available on per memcg level for memcg aware
shrinkers, so don't need allocate shrinker->nr_deferred for such
shrinkers anymore.
The prealloc_memcg_shrinker() would return -ENOSYS if !CONFIG_MEMCG or
memcg is disabled by kernel command line, then shrinker's
SHRINKER_MEMCG_AWARE flag would be cleared. This makes the
implementation of this patch simpler.
Link: https://lkml.kernel.org/r/20210311190845.9708-12-shy828301@gmail.com
Signed-off-by: Yang Shi <shy828301@gmail.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Acked-by: Roman Gushchin <guro@fb.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Use per memcg's nr_deferred for memcg aware shrinkers. The shrinker's
nr_deferred will be used in the following cases:
1. Non memcg aware shrinkers
2. !CONFIG_MEMCG
3. memcg is disabled by boot parameter
Link: https://lkml.kernel.org/r/20210311190845.9708-11-shy828301@gmail.com
Signed-off-by: Yang Shi <shy828301@gmail.com>
Acked-by: Roman Gushchin <guro@fb.com>
Acked-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently the number of deferred objects are per shrinker, but some
slabs, for example, vfs inode/dentry cache are per memcg, this would
result in poor isolation among memcgs.
The deferred objects typically are generated by __GFP_NOFS allocations,
one memcg with excessive __GFP_NOFS allocations may blow up deferred
objects, then other innocent memcgs may suffer from over shrink,
excessive reclaim latency, etc.
For example, two workloads run in memcgA and memcgB respectively,
workload in B is vfs heavy workload. Workload in A generates excessive
deferred objects, then B's vfs cache might be hit heavily (drop half of
caches) by B's limit reclaim or global reclaim.
We observed this hit in our production environment which was running vfs
heavy workload shown as the below tracing log:
<...>-409454 [016] .... 28286961.747146: mm_shrink_slab_start: super_cache_scan+0x0/0x1a0 ffff9a83046f3458:
nid: 1 objects to shrink 3641681686040 gfp_flags GFP_HIGHUSER_MOVABLE|__GFP_ZERO pgs_scanned 1 lru_pgs 15721
cache items 246404277 delta 31345 total_scan 123202138
<...>-409454 [022] .... 28287105.928018: mm_shrink_slab_end: super_cache_scan+0x0/0x1a0 ffff9a83046f3458:
nid: 1 unused scan count 3641681686040 new scan count 3641798379189 total_scan 602
last shrinker return val 123186855
The vfs cache and page cache ratio was 10:1 on this machine, and half of
caches were dropped. This also resulted in significant amount of page
caches were dropped due to inodes eviction.
Make nr_deferred per memcg for memcg aware shrinkers would solve the
unfairness and bring better isolation.
The following patch will add nr_deferred to parent memcg when memcg
offline. To preserve nr_deferred when reparenting memcgs to root, root
memcg needs shrinker_info allocated too.
When memcg is not enabled (!CONFIG_MEMCG or memcg disabled), the
shrinker's nr_deferred would be used. And non memcg aware shrinkers use
shrinker's nr_deferred all the time.
Link: https://lkml.kernel.org/r/20210311190845.9708-10-shy828301@gmail.com
Signed-off-by: Yang Shi <shy828301@gmail.com>
Acked-by: Roman Gushchin <guro@fb.com>
Acked-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently registered shrinker is indicated by non-NULL
shrinker->nr_deferred. This approach is fine with nr_deferred at the
shrinker level, but the following patches will move MEMCG_AWARE
shrinkers' nr_deferred to memcg level, so their shrinker->nr_deferred
would always be NULL. This would prevent the shrinkers from
unregistering correctly.
Remove SHRINKER_REGISTERING since we could check if shrinker is
registered successfully by the new flag.
Link: https://lkml.kernel.org/r/20210311190845.9708-9-shy828301@gmail.com
Signed-off-by: Yang Shi <shy828301@gmail.com>
Acked-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Roman Gushchin <guro@fb.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The shrinker_info is dereferenced in a couple of places via
rcu_dereference_protected with different calling conventions, for
example, using mem_cgroup_nodeinfo helper or dereferencing
memcg->nodeinfo[nid]->shrinker_info. And the later patch will add more
dereference places.
So extract the dereference into a helper to make the code more readable.
No functional change.
[akpm@linux-foundation.org: retain rcu_dereference_protected() in free_shrinker_info(), per Hugh]
Link: https://lkml.kernel.org/r/20210311190845.9708-8-shy828301@gmail.com
Signed-off-by: Yang Shi <shy828301@gmail.com>
Acked-by: Roman Gushchin <guro@fb.com>
Acked-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The following patch is going to add nr_deferred into shrinker_map, the
change will make shrinker_map not only include map anymore, so rename it
to "memcg_shrinker_info". And this should make the patch adding
nr_deferred cleaner and readable and make review easier. Also remove the
"memcg_" prefix.
Link: https://lkml.kernel.org/r/20210311190845.9708-7-shy828301@gmail.com
Signed-off-by: Yang Shi <shy828301@gmail.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Acked-by: Roman Gushchin <guro@fb.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Using kvfree_rcu() to free the old shrinker_maps instead of call_rcu().
We don't have to define a dedicated callback for call_rcu() anymore.
Link: https://lkml.kernel.org/r/20210311190845.9708-6-shy828301@gmail.com
Signed-off-by: Yang Shi <shy828301@gmail.com>
Acked-by: Roman Gushchin <guro@fb.com>
Acked-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Both memcg_shrinker_map_size and shrinker_nr_max is maintained, but
actually the map size can be calculated via shrinker_nr_max, so it seems
unnecessary to keep both. Remove memcg_shrinker_map_size since
shrinker_nr_max is also used by iterating the bit map.
Link: https://lkml.kernel.org/r/20210311190845.9708-5-shy828301@gmail.com
Signed-off-by: Yang Shi <shy828301@gmail.com>
Acked-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Acked-by: Roman Gushchin <guro@fb.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Since memcg_shrinker_map_size just can be changed under holding
shrinker_rwsem exclusively, the read side can be protected by holding read
lock, so it sounds superfluous to have a dedicated mutex.
Kirill Tkhai suggested use write lock since:
* We want the assignment to shrinker_maps is visible for shrink_slab_memcg().
* The rcu_dereference_protected() dereferrencing in shrink_slab_memcg(), but
in case of we use READ lock in alloc_shrinker_maps(), the dereferrencing
is not actually protected.
* READ lock makes alloc_shrinker_info() racy against memory allocation fail.
alloc_shrinker_info()->free_shrinker_info() may free memory right after
shrink_slab_memcg() dereferenced it. You may say
shrink_slab_memcg()->mem_cgroup_online() protects us from it? Yes, sure,
but this is not the thing we want to remember in the future, since this
spreads modularity.
And a test with heavy paging workload didn't show write lock makes things worse.
Link: https://lkml.kernel.org/r/20210311190845.9708-4-shy828301@gmail.com
Signed-off-by: Yang Shi <shy828301@gmail.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Acked-by: Roman Gushchin <guro@fb.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The shrinker map management is not purely memcg specific, it is at the
intersection between memory cgroup and shrinkers. It's allocation and
assignment of a structure, and the only memcg bit is the map is being
stored in a memcg structure. So move the shrinker_maps handling code
into vmscan.c for tighter integration with shrinker code, and remove the
"memcg_" prefix. There is no functional change.
Link: https://lkml.kernel.org/r/20210311190845.9708-3-shy828301@gmail.com
Signed-off-by: Yang Shi <shy828301@gmail.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Acked-by: Roman Gushchin <guro@fb.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "Make shrinker's nr_deferred memcg aware", v10.
Recently huge amount one-off slab drop was seen on some vfs metadata
heavy workloads, it turned out there were huge amount accumulated
nr_deferred objects seen by the shrinker.
On our production machine, I saw absurd number of nr_deferred shown as
the below tracing result:
<...>-48776 [032] .... 27970562.458916: mm_shrink_slab_start:
super_cache_scan+0x0/0x1a0 ffff9a83046f3458: nid: 0 objects to shrink
2531805877005 gfp_flags GFP_HIGHUSER_MOVABLE pgs_scanned 32 lru_pgs
9300 cache items 1667 delta 11 total_scan 833
There are 2.5 trillion deferred objects on one node, assuming all of them
are dentry (192 bytes per object), so the total size of deferred on one
node is ~480TB. It is definitely ridiculous.
I managed to reproduce this problem with kernel build workload plus
negative dentry generator.
First step, run the below kernel build test script:
NR_CPUS=`cat /proc/cpuinfo | grep -e processor | wc -l`
cd /root/Buildarea/linux-stable
for i in `seq 1500`; do
cgcreate -g memory:kern_build
echo 4G > /sys/fs/cgroup/memory/kern_build/memory.limit_in_bytes
echo 3 > /proc/sys/vm/drop_caches
cgexec -g memory:kern_build make clean > /dev/null 2>&1
cgexec -g memory:kern_build make -j$NR_CPUS > /dev/null 2>&1
cgdelete -g memory:kern_build
done
Then run the below negative dentry generator script:
NR_CPUS=`cat /proc/cpuinfo | grep -e processor | wc -l`
mkdir /sys/fs/cgroup/memory/test
echo $$ > /sys/fs/cgroup/memory/test/tasks
for i in `seq $NR_CPUS`; do
while true; do
FILE=`head /dev/urandom | tr -dc A-Za-z0-9 | head -c 64`
cat $FILE 2>/dev/null
done &
done
Then kswapd will shrink half of dentry cache in just one loop as the below
tracing result showed:
kswapd0-475 [028] .... 305968.252561: mm_shrink_slab_start: super_cache_scan+0x0/0x190 0000000024acf00c: nid: 0 objects to shrink 4994376020 gfp_flags GFP_KERNEL cache items 93689873 delta 45746 total_scan 46844936 priority 12
kswapd0-475 [021] .... 306013.099399: mm_shrink_slab_end: super_cache_scan+0x0/0x190 0000000024acf00c: nid: 0 unused scan count 4994376020 new scan count 4947576838 total_scan 8 last shrinker return val 46844928
There were huge number of deferred objects before the shrinker was called,
the behavior does match the code but it might be not desirable from the
user's stand of point.
The excessive amount of nr_deferred might be accumulated due to various
reasons, for example:
* GFP_NOFS allocation
* Significant times of small amount scan (< scan_batch, 1024 for vfs
metadata)
However the LRUs of slabs are per memcg (memcg-aware shrinkers) but the
deferred objects is per shrinker, this may have some bad effects:
* Poor isolation among memcgs. Some memcgs which happen to have
frequent limit reclaim may get nr_deferred accumulated to a huge number,
then other innocent memcgs may take the fall. In our case the main
workload was hit.
* Unbounded deferred objects. There is no cap for deferred objects, it
can outgrow ridiculously as the tracing result showed.
* Easy to get out of control. Although shrinkers take into account
deferred objects, but it can go out of control easily. One
misconfigured memcg could incur absurd amount of deferred objects in a
period of time.
* Sort of reclaim problems, i.e. over reclaim, long reclaim latency,
etc. There may be hundred GB slab caches for vfe metadata heavy
workload, shrink half of them may take minutes. We observed latency
spike due to the prolonged reclaim.
These issues also have been discussed in
https://lore.kernel.org/linux-mm/20200916185823.5347-1-shy828301@gmail.com/.
The patchset is the outcome of that discussion.
So this patchset makes nr_deferred per-memcg to tackle the problem. It
does:
* Have memcg_shrinker_deferred per memcg per node, just like what
shrinker_map does. Instead it is an atomic_long_t array, each element
represent one shrinker even though the shrinker is not memcg aware, this
simplifies the implementation. For memcg aware shrinkers, the deferred
objects are just accumulated to its own memcg. The shrinkers just see
nr_deferred from its own memcg. Non memcg aware shrinkers still use
global nr_deferred from struct shrinker.
* Once the memcg is offlined, its nr_deferred will be reparented to its
parent along with LRUs.
* The root memcg has memcg_shrinker_deferred array too. It simplifies
the handling of reparenting to root memcg.
* Cap nr_deferred to 2x of the length of lru. The idea is borrowed from
Dave Chinner's series
(https://lore.kernel.org/linux-xfs/20191031234618.15403-1-david@fromorbit.com/)
The downside is each memcg has to allocate extra memory to store the
nr_deferred array. On our production environment, there are typically
around 40 shrinkers, so each memcg needs ~320 bytes. 10K memcgs would
need ~3.2MB memory. It seems fine.
We have been running the patched kernel on some hosts of our fleet (test
and production) for months, it works very well. The monitor data shows
the working set is sustained as expected.
This patch (of 13):
The tracepoint's nid should show what node the shrink happens on, the
start tracepoint uses nid from shrinkctl, but the nid might be set to 0
before end tracepoint if the shrinker is not NUMA aware, so the tracing
log may show the shrink happens on one node but end up on the other node.
It seems confusing. And the following patch will remove using nid
directly in do_shrink_slab(), this patch also helps cleanup the code.
Link: https://lkml.kernel.org/r/20210311190845.9708-1-shy828301@gmail.com
Link: https://lkml.kernel.org/r/20210311190845.9708-2-shy828301@gmail.com
Signed-off-by: Yang Shi <shy828301@gmail.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Roman Gushchin <guro@fb.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
It is currently not obvious that the RECLAIM_* bits are part of the uapi
since they are defined in vmscan.c. Move them to a uapi header to make it
obvious.
This should have no functional impact.
Link: https://lkml.kernel.org/r/20210219172557.08074910@viggo.jf.intel.com
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Ben Widawsky <ben.widawsky@intel.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Daniel Wagner <dwagner@suse.de>
Cc: "Tobin C. Harding" <tobin@kernel.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Qian Cai <cai@lca.pw>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
alloc_contig_range() will fail if it finds a HugeTLB page within the
range, without a chance to handle them. Since HugeTLB pages can be
migrated as any LRU or Movable page, it does not make sense to bail out
without trying. Enable the interface to recognize in-use HugeTLB pages so
we can migrate them, and have much better chances to succeed the call.
Link: https://lkml.kernel.org/r/20210419075413.1064-7-osalvador@suse.de
Signed-off-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
I went to go add a new RECLAIM_* mode for the zone_reclaim_mode sysctl.
Like a good kernel developer, I also went to go update the
documentation. I noticed that the bits in the documentation didn't
match the bits in the #defines.
The VM never explicitly checks the RECLAIM_ZONE bit. The bit is,
however implicitly checked when checking 'node_reclaim_mode==0'. The
RECLAIM_ZONE #define was removed in a cleanup. That, by itself is fine.
But, when the bit was removed (bit 0) the _other_ bit locations also got
changed. That's not OK because the bit values are documented to mean
one specific thing. Users surely do not expect the meaning to change
from kernel to kernel.
The end result is that if someone had a script that did:
sysctl vm.zone_reclaim_mode=1
it would have gone from enabling node reclaim for clean unmapped pages
to writing out pages during node reclaim after the commit in question.
That's not great.
Put the bits back the way they were and add a comment so something like
this is a bit harder to do again. Update the documentation to make it
clear that the first bit is ignored.
Link: https://lkml.kernel.org/r/20210219172555.FF0CDF23@viggo.jf.intel.com
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Fixes: 648b5cf368 ("mm/vmscan: remove unused RECLAIM_OFF/RECLAIM_ZONE")
Reviewed-by: Ben Widawsky <ben.widawsky@intel.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Daniel Wagner <dwagner@suse.de>
Cc: "Tobin C. Harding" <tobin@kernel.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Qian Cai <cai@lca.pw>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
All other references to the function were removed after
commit b910718a94 ("mm: vmscan: detect file thrashing at the reclaim
root").
Link: https://lore.kernel.org/linux-mm/20201207220949.830352-11-yuzhao@google.com/
Link: https://lkml.kernel.org/r/20210122220600.906146-11-yuzhao@google.com
Signed-off-by: Yu Zhao <yuzhao@google.com>
Reviewed-by: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Roman Gushchin <guro@fb.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Move scattered VM_BUG_ONs to two essential places that cover all
lru list additions and deletions.
Link: https://lore.kernel.org/linux-mm/20201207220949.830352-8-yuzhao@google.com/
Link: https://lkml.kernel.org/r/20210122220600.906146-8-yuzhao@google.com
Signed-off-by: Yu Zhao <yuzhao@google.com>
Cc: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Roman Gushchin <guro@fb.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Similar to page_off_lru(), the new function does non-atomic clearing
of PageLRU() in addition to PageActive() and PageUnevictable(), on a
page that has no references left.
If PageActive() and PageUnevictable() are both set, refuse to clear
either and leave them to bad_page(). This is a behavior change that
is meant to help debug.
Link: https://lore.kernel.org/linux-mm/20201207220949.830352-7-yuzhao@google.com/
Link: https://lkml.kernel.org/r/20210122220600.906146-7-yuzhao@google.com
Signed-off-by: Yu Zhao <yuzhao@google.com>
Cc: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Roman Gushchin <guro@fb.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The parameter is redundant in the sense that it can be potentially
extracted from the "struct page" parameter by page_lru(). We need to
make sure that existing PageActive() or PageUnevictable() remains
until the function returns. A few places don't conform, and simple
reordering fixes them.
This patch may have left page_off_lru() seemingly odd, and we'll take
care of it in the next patch.
Link: https://lore.kernel.org/linux-mm/20201207220949.830352-6-yuzhao@google.com/
Link: https://lkml.kernel.org/r/20210122220600.906146-6-yuzhao@google.com
Signed-off-by: Yu Zhao <yuzhao@google.com>
Cc: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Roman Gushchin <guro@fb.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The "enum lru_list" parameter to add_page_to_lru_list() and
add_page_to_lru_list_tail() is redundant in the sense that it can
be extracted from the "struct page" parameter by page_lru().
A caveat is that we need to make sure PageActive() or
PageUnevictable() is correctly set or cleared before calling
these two functions. And they are indeed.
Link: https://lore.kernel.org/linux-mm/20201207220949.830352-4-yuzhao@google.com/
Link: https://lkml.kernel.org/r/20210122220600.906146-4-yuzhao@google.com
Signed-off-by: Yu Zhao <yuzhao@google.com>
Cc: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Roman Gushchin <guro@fb.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "mm: lru related cleanups", v2.
The cleanups are intended to reduce the verbosity in lru list operations
and make them less error-prone. A typical example would be how the
patches change __activate_page():
static void __activate_page(struct page *page, struct lruvec *lruvec)
{
if (!PageActive(page) && !PageUnevictable(page)) {
- int lru = page_lru_base_type(page);
int nr_pages = thp_nr_pages(page);
- del_page_from_lru_list(page, lruvec, lru);
+ del_page_from_lru_list(page, lruvec);
SetPageActive(page);
- lru += LRU_ACTIVE;
- add_page_to_lru_list(page, lruvec, lru);
+ add_page_to_lru_list(page, lruvec);
trace_mm_lru_activate(page);
There are a few more places like __activate_page() and they are
unnecessarily repetitive in terms of figuring out which list a page should
be added onto or deleted from. And with the duplicated code removed, they
are easier to read, IMO.
Patch 1 to 5 basically cover the above. Patch 6 and 7 make code more
robust by improving bug reporting. Patch 8, 9 and 10 take care of some
dangling helpers left in header files.
This patch (of 10):
There is add_page_to_lru_list(), and move_pages_to_lru() should reuse it,
not duplicate it.
Link: https://lkml.kernel.org/r/20210122220600.906146-1-yuzhao@google.com
Link: https://lore.kernel.org/linux-mm/20201207220949.830352-2-yuzhao@google.com/
Link: https://lkml.kernel.org/r/20210122220600.906146-2-yuzhao@google.com
Signed-off-by: Yu Zhao <yuzhao@google.com>
Reviewed-by: Alex Shi <alex.shi@linux.alibaba.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The function just returns 2 results, so using a 'switch' to deal with its
result is unnecessary. Also simplify it to a bool func as Vlastimil
suggested.
Also remove 'goto' by reusing list_move(), and take Matthew Wilcox's
suggestion to update comments in function.
Link: https://lkml.kernel.org/r/728874d7-2d93-4049-68c1-dcc3b2d52ccd@linux.alibaba.com
Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Yu Zhao <yuzhao@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
So technically there is nothing wrong with adding a pinned page to the
swap cache, but the pinning obviously means that the page can't actually
be free'd right now anyway, so it's a bit pointless.
However, the real problem is not with it being a bit pointless: the real
issue is that after we've added it to the swap cache, we'll try to unmap
the page. That will succeed, because the code in mm/rmap.c doesn't know
or care about pinned pages.
Even the unmapping isn't fatal per se, since the page will stay around
in memory due to the pinning, and we do hold the connection to it using
the swap cache. But when we then touch it next and take a page fault,
the logic in do_swap_page() will map it back into the process as a
possibly read-only page, and we'll then break the page association on
the next COW fault.
Honestly, this issue could have been fixed in any of those other places:
(a) we could refuse to unmap a pinned page (which makes conceptual
sense), or (b) we could make sure to re-map a pinned page writably in
do_swap_page(), or (c) we could just make do_wp_page() not COW the
pinned page (which was what we historically did before that "mm:
do_wp_page() simplification" commit).
But while all of them are equally valid models for breaking this chain,
not putting pinned pages into the swap cache in the first place is the
simplest one by far.
It's also the safest one: the reason why do_wp_page() was changed in the
first place was that getting the "can I re-use this page" wrong is so
fraught with errors. If you do it wrong, you end up with an incorrectly
shared page.
As a result, using "page_maybe_dma_pinned()" in either do_wp_page() or
do_swap_page() would be a serious bug since it is only a (very good)
heuristic. Re-using the page requires a hard black-and-white rule with
no room for ambiguity.
In contrast, saying "this page is very likely dma pinned, so let's not
add it to the swap cache and try to unmap it" is an obviously safe thing
to do, and if the heuristic might very rarely be a false positive, no
harm is done.
Fixes: 09854ba94c ("mm: do_wp_page() simplification")
Reported-and-tested-by: Martin Raiber <martin@urbackup.org>
Cc: Pavel Begunkov <asml.silence@gmail.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Peter Xu <peterx@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Since we changed the pgdat->lru_lock to lruvec->lru_lock, it's time to fix
the incorrect comments in code. Also fixed some zone->lru_lock comment
error from ancient time. etc.
I struggled to understand the comment above move_pages_to_lru() (surely
it never calls page_referenced()), and eventually realized that most of
it had got separated from shrink_active_list(): move that comment back.
Link: https://lkml.kernel.org/r/1604566549-62481-20-git-send-email-alex.shi@linux.alibaba.com
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Tejun Heo <tj@kernel.org>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Jann Horn <jannh@google.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Alexander Duyck <alexander.duyck@gmail.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: "Chen, Rong A" <rong.a.chen@intel.com>
Cc: Daniel Jordan <daniel.m.jordan@oracle.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mika Penttilä <mika.penttila@nextfour.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Yang Shi <yang.shi@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add relock_page_lruvec() to replace repeated same code, no functional
change.
When testing for relock we can avoid the need for RCU locking if we simply
compare the page pgdat and memcg pointers versus those that the lruvec is
holding. By doing this we can avoid the extra pointer walks and accesses
of the memory cgroup.
In addition we can avoid the checks entirely if lruvec is currently NULL.
[alex.shi@linux.alibaba.com: use page_memcg()]
Link: https://lkml.kernel.org/r/66d8e79d-7ec6-bfbc-1c82-bf32db3ae5b7@linux.alibaba.com
Link: https://lkml.kernel.org/r/1604566549-62481-19-git-send-email-alex.shi@linux.alibaba.com
Signed-off-by: Alexander Duyck <alexander.h.duyck@linux.intel.com>
Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com>
Acked-by: Hugh Dickins <hughd@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: Tejun Heo <tj@kernel.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: "Chen, Rong A" <rong.a.chen@intel.com>
Cc: Daniel Jordan <daniel.m.jordan@oracle.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Jann Horn <jannh@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mika Penttilä <mika.penttila@nextfour.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Yang Shi <yang.shi@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch moves per node lru_lock into lruvec, thus bring a lru_lock for
each of memcg per node. So on a large machine, each of memcg don't have
to suffer from per node pgdat->lru_lock competition. They could go fast
with their self lru_lock.
After move memcg charge before lru inserting, page isolation could
serialize page's memcg, then per memcg lruvec lock is stable and could
replace per node lru lock.
In isolate_migratepages_block(), compact_unlock_should_abort and
lock_page_lruvec_irqsave are open coded to work with compact_control.
Also add a debug func in locking which may give some clues if there are
sth out of hands.
Daniel Jordan's testing show 62% improvement on modified readtwice case on
his 2P * 10 core * 2 HT broadwell box.
https://lore.kernel.org/lkml/20200915165807.kpp7uhiw7l3loofu@ca-dmjordan1.us.oracle.com/
Hugh Dickins helped on the patch polish, thanks!
[alex.shi@linux.alibaba.com: fix comment typo]
Link: https://lkml.kernel.org/r/5b085715-292a-4b43-50b3-d73dc90d1de5@linux.alibaba.com
[alex.shi@linux.alibaba.com: use page_memcg()]
Link: https://lkml.kernel.org/r/5a4c2b72-7ee8-2478-fc0e-85eb83aafec4@linux.alibaba.com
Link: https://lkml.kernel.org/r/1604566549-62481-18-git-send-email-alex.shi@linux.alibaba.com
Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com>
Acked-by: Hugh Dickins <hughd@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Rong Chen <rong.a.chen@intel.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Yang Shi <yang.shi@linux.alibaba.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: Daniel Jordan <daniel.m.jordan@oracle.com>
Cc: Alexander Duyck <alexander.duyck@gmail.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Jann Horn <jannh@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mika Penttilä <mika.penttila@nextfour.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wei Yang <richard.weiyang@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently, compaction would get the lru_lock and then do page isolation
which works fine with pgdat->lru_lock, since any page isoltion would
compete for the lru_lock. If we want to change to memcg lru_lock, we have
to isolate the page before getting lru_lock, thus isoltion would block
page's memcg change which relay on page isoltion too. Then we could
safely use per memcg lru_lock later.
The new page isolation use previous introduced TestClearPageLRU() + pgdat
lru locking which will be changed to memcg lru lock later.
Hugh Dickins <hughd@google.com> fixed following bugs in this patch's early
version:
Fix lots of crashes under compaction load: isolate_migratepages_block()
must clean up appropriately when rejecting a page, setting PageLRU again
if it had been cleared; and a put_page() after get_page_unless_zero()
cannot safely be done while holding locked_lruvec - it may turn out to be
the final put_page(), which will take an lruvec lock when PageLRU.
And move __isolate_lru_page_prepare back after get_page_unless_zero to
make trylock_page() safe: trylock_page() is not safe to use at this time:
its setting PG_locked can race with the page being freed or allocated
("Bad page"), and can also erase flags being set by one of those "sole
owners" of a freshly allocated page who use non-atomic __SetPageFlag().
Link: https://lkml.kernel.org/r/1604566549-62481-16-git-send-email-alex.shi@linux.alibaba.com
Suggested-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com>
Acked-by: Hugh Dickins <hughd@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Alexander Duyck <alexander.duyck@gmail.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: "Chen, Rong A" <rong.a.chen@intel.com>
Cc: Daniel Jordan <daniel.m.jordan@oracle.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Jann Horn <jannh@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mika Penttilä <mika.penttila@nextfour.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Yang Shi <yang.shi@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently lru_lock still guards both lru list and page's lru bit, that's
ok. but if we want to use specific lruvec lock on the page, we need to
pin down the page's lruvec/memcg during locking. Just taking lruvec lock
first may be undermined by the page's memcg charge/migration. To fix this
problem, we will clear the lru bit out of locking and use it as pin down
action to block the page isolation in memcg changing.
So now a standard steps of page isolation is following:
1, get_page(); #pin the page avoid to be free
2, TestClearPageLRU(); #block other isolation like memcg change
3, spin_lock on lru_lock; #serialize lru list access
4, delete page from lru list;
This patch start with the first part: TestClearPageLRU, which combines
PageLRU check and ClearPageLRU into a macro func TestClearPageLRU. This
function will be used as page isolation precondition to prevent other
isolations some where else. Then there are may !PageLRU page on lru list,
need to remove BUG() checking accordingly.
There 2 rules for lru bit now:
1, the lru bit still indicate if a page on lru list, just in some
temporary moment(isolating), the page may have no lru bit when
it's on lru list. but the page still must be on lru list when the
lru bit set.
2, have to remove lru bit before delete it from lru list.
As Andrew Morton mentioned this change would dirty cacheline for a page
which isn't on the LRU. But the loss would be acceptable in Rong Chen
<rong.a.chen@intel.com> report:
https://lore.kernel.org/lkml/20200304090301.GB5972@shao2-debian/
Link: https://lkml.kernel.org/r/1604566549-62481-15-git-send-email-alex.shi@linux.alibaba.com
Suggested-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com>
Acked-by: Hugh Dickins <hughd@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Alexander Duyck <alexander.duyck@gmail.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Daniel Jordan <daniel.m.jordan@oracle.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Jann Horn <jannh@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mika Penttilä <mika.penttila@nextfour.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Yang Shi <yang.shi@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Isolated page shouldn't be recharged by memcg since the memcg migration
isn't possible at the time. All pages were isolated from the same lruvec
(and isolation inhibits memcg migration). So remove unnecessary
regetting.
Thanks to Alexander Duyck for pointing this out.
Link: https://lkml.kernel.org/r/1604566549-62481-12-git-send-email-alex.shi@linux.alibaba.com
Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com>
Acked-by: Hugh Dickins <hughd@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Alexander Duyck <alexander.duyck@gmail.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: "Chen, Rong A" <rong.a.chen@intel.com>
Cc: Daniel Jordan <daniel.m.jordan@oracle.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Jann Horn <jannh@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mika Penttilä <mika.penttila@nextfour.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Yang Shi <yang.shi@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We have to move lru_lock into lru_note_cost, since it cycle up on memcg
tree, for future per lruvec lru_lock replace. It's a bit ugly and may
cost a bit more locking, but benefit from multiple memcg locking could
cover the lost.
Link: https://lkml.kernel.org/r/1604566549-62481-11-git-send-email-alex.shi@linux.alibaba.com
Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com>
Acked-by: Hugh Dickins <hughd@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Alexander Duyck <alexander.duyck@gmail.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: "Chen, Rong A" <rong.a.chen@intel.com>
Cc: Daniel Jordan <daniel.m.jordan@oracle.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Jann Horn <jannh@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mika Penttilä <mika.penttila@nextfour.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Yang Shi <yang.shi@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We don't have to add a freeable page into lru and then remove from it.
This change saves a couple of actions and makes the moving more clear.
The SetPageLRU needs to be kept before put_page_testzero for list
integrity, otherwise:
#0 move_pages_to_lru #1 release_pages
if !put_page_testzero
if (put_page_testzero())
!PageLRU //skip lru_lock
SetPageLRU()
list_add(&page->lru,)
list_add(&page->lru,)
[akpm@linux-foundation.org: coding style fixes]
Link: https://lkml.kernel.org/r/1604566549-62481-6-git-send-email-alex.shi@linux.alibaba.com
Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com>
Acked-by: Hugh Dickins <hughd@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Tejun Heo <tj@kernel.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Alexander Duyck <alexander.duyck@gmail.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: "Chen, Rong A" <rong.a.chen@intel.com>
Cc: Daniel Jordan <daniel.m.jordan@oracle.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Jann Horn <jannh@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mika Penttilä <mika.penttila@nextfour.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Yang Shi <yang.shi@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In preparation to enable -Wimplicit-fallthrough for Clang, fix a couple of
warnings by explicitly adding a break statement instead of just letting
the code fall through to the next, and by adding a fallthrough
pseudo-keyword in places where the code is intended to fall through.
Link: https://github.com/KSPP/linux/issues/115
Link: https://lkml.kernel.org/r/f5756988b8842a3f10008fbc5b0a654f828920a9.1605896059.git.gustavoars@kernel.org
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "mm: misc migrate cleanup and improvement", v3.
This patch (of 5):
The commit 9f4e41f471 ("mm: refactor truncate_complete_page()")
refactored truncate_complete_page(), and it is not existed anymore,
correct the comment in vmscan and migrate to avoid confusion.
Link: https://lkml.kernel.org/r/20201113205359.556831-1-shy828301@gmail.com
Link: https://lkml.kernel.org/r/20201113205359.556831-2-shy828301@gmail.com
Signed-off-by: Yang Shi <shy828301@gmail.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Song Liu <songliubraving@fb.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
No point in having the filename inside the file.
Link: https://lkml.kernel.org/r/20201115141541.3878-1-hymmsx.yu@gmail.com
Signed-off-by: logic.yu <hymmsx.yu@gmail.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The refactoring to kswapd() in commit e716f2eb24 ("mm, vmscan: prevent
kswapd sleeping prematurely due to mismatched classzone_idx") turned an
assignment to reclaim_order into a dead store, as in all further paths,
reclaim_order will be assigned again before it is used.
make clang-analyzer on x86_64 tinyconfig caught my attention with:
mm/vmscan.c: warning: Although the value stored to 'reclaim_order' is used in the enclosing expression, the value is never actually read from 'reclaim_order' [clang-analyzer-deadcode.DeadStores]
Compilers will detect this unneeded assignment and optimize this anyway.
So, the resulting binary is identical before and after this change.
Simplify the code and remove unneeded assignment to make clang-analyzer
happy.
No functional change. No change in binary code.
Link: https://lkml.kernel.org/r/20201004125827.17679-1-lukas.bulwahn@gmail.com
Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Nathan Chancellor <natechancellor@gmail.com>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Since commit 369ea8242c ("mm/rmap: update to new mmu_notifier semantic
v2"), the code to check the secondary MMU's page table access bit is
broken for !(TTU_IGNORE_ACCESS) because the page is unmapped from the
secondary MMU's page table before the check. More specifically for those
secondary MMUs which unmap the memory in
mmu_notifier_invalidate_range_start() like kvm.
However memory reclaim is the only user of !(TTU_IGNORE_ACCESS) or the
absence of TTU_IGNORE_ACCESS and it explicitly performs the page table
access check before trying to unmap the page. So, at worst the reclaim
will miss accesses in a very short window if we remove page table access
check in unmapping code.
There is an unintented consequence of !(TTU_IGNORE_ACCESS) for the memcg
reclaim. From memcg reclaim the page_referenced() only account the
accesses from the processes which are in the same memcg of the target page
but the unmapping code is considering accesses from all the processes, so,
decreasing the effectiveness of memcg reclaim.
The simplest solution is to always assume TTU_IGNORE_ACCESS in unmapping
code.
Link: https://lkml.kernel.org/r/20201104231928.1494083-1-shakeelb@google.com
Fixes: 369ea8242c ("mm/rmap: update to new mmu_notifier semantic v2")
Signed-off-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Previously the negated unsigned long would be cast back to signed long
which would have the correct negative value. After commit 730ec8c01a
("mm/vmscan.c: change prototype for shrink_page_list"), the large
unsigned int converts to a large positive signed long.
Symptoms include CMA allocations hanging forever holding the cma_mutex
due to alloc_contig_range->...->isolate_migratepages_block waiting
forever in "while (unlikely(too_many_isolated(pgdat)))".
[akpm@linux-foundation.org: fix -stat.nr_lazyfree_fail as well, per Michal]
Fixes: 730ec8c01a ("mm/vmscan.c: change prototype for shrink_page_list")
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Vaneet Narang <v.narang@samsung.com>
Cc: Maninder Singh <maninder1.s@samsung.com>
Cc: Amit Sahrawat <a.sahrawat@samsung.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: <stable@vger.kernel.org>
Link: https://lkml.kernel.org/r/20201029032320.1448441-1-npiggin@gmail.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Remove the assumption that a compound page has HPAGE_PMD_NR pins from the
page cache.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: SeongJae Park <sjpark@amazon.de>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: "Huang, Ying" <ying.huang@intel.com>
Link: https://lkml.kernel.org/r/20200908195539.25896-12-willy@infradead.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We have observed that drop_caches can take a considerable amount of
time (<put data here>). Especially when there are many memcgs involved
because they are adding an additional overhead.
It is quite unfortunate that the operation cannot be interrupted by a
signal currently. Add a check for fatal signals into the main loop so
that userspace can control early bailout.
There are two reasons:
1. We have too many memcgs, even though one object freed in one memcg,
the sum of object is bigger than 10.
2. We spend a lot of time in traverse memcg once. So, the memcg who
traversed at the first have been freed many objects. Traverse memcg
next time, the freed count bigger than 10 again.
We can get the following info through 'ps':
root:~# ps -aux | grep drop
root 357956 ... R Aug25 21119854:55 echo 3 > /proc/sys/vm/drop_caches
root 1771385 ... R Aug16 21146421:17 echo 3 > /proc/sys/vm/drop_caches
root 1986319 ... R 18:56 117:27 echo 3 > /proc/sys/vm/drop_caches
root 2002148 ... R Aug24 5720:39 echo 3 > /proc/sys/vm/drop_caches
root 2564666 ... R 18:59 113:58 echo 3 > /proc/sys/vm/drop_caches
root 2639347 ... R Sep03 2383:39 echo 3 > /proc/sys/vm/drop_caches
root 3904747 ... R 03:35 993:31 echo 3 > /proc/sys/vm/drop_caches
root 4016780 ... R Aug21 7882:18 echo 3 > /proc/sys/vm/drop_caches
Use bpftrace follow 'freed' value in drop_slab_node:
root:~# bpftrace -e 'kprobe:drop_slab_node+70 {@ret=hist(reg("bp")); }'
Attaching 1 probe...
^B^C
@ret:
[64, 128) 1 | |
[128, 256) 28 | |
[256, 512) 107 |@ |
[512, 1K) 298 |@@@ |
[1K, 2K) 613 |@@@@@@@ |
[2K, 4K) 4435 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@|
[4K, 8K) 442 |@@@@@ |
[8K, 16K) 299 |@@@ |
[16K, 32K) 100 |@ |
[32K, 64K) 139 |@ |
[64K, 128K) 56 | |
[128K, 256K) 26 | |
[256K, 512K) 2 | |
In the while loop, we can check whether the TASK_KILLABLE signal is set,
if so, we should break the loop.
Signed-off-by: Chunxin Zang <zangchunxin@bytedance.com>
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Chris Down <chris@chrisdown.name>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Matthew Wilcox <willy@infradead.org>
Link: https://lkml.kernel.org/r/20200909152047.27905-1-zangchunxin@bytedance.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
check_move_unevictable_pages() is used in making unevictable shmem pages
evictable: by shmem_unlock_mapping(), drm_gem_check_release_pagevec() and
i915/gem check_release_pagevec(). Those may pass down subpages of a huge
page, when /sys/kernel/mm/transparent_hugepage/shmem_enabled is "force".
That does not crash or warn at present, but the accounting of vmstats
unevictable_pgs_scanned and unevictable_pgs_rescued is inconsistent:
scanned being incremented on each subpage, rescued only on the head (since
tails already appear evictable once the head has been updated).
5.8 commit 5d91f31faf ("mm: swap: fix vmstats for huge page") has
established that vm_events in general (and unevictable_pgs_rescued in
particular) should count every subpage: so follow that precedent here.
Do this in such a way that if mem_cgroup_page_lruvec() is made stricter
(to check page->mem_cgroup is always set), no problem: skip the tails
before calling it, and add thp_nr_pages() to vmstats on the head.
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Yang Shi <shy828301@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Qian Cai <cai@lca.pw>
Link: http://lkml.kernel.org/r/alpine.LSU.2.11.2008301405000.5954@eggly.anvils
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We've met softlockup with "CONFIG_PREEMPT_NONE=y", when the target memcg
doesn't have any reclaimable memory.
It can be easily reproduced as below:
watchdog: BUG: soft lockup - CPU#0 stuck for 111s![memcg_test:2204]
CPU: 0 PID: 2204 Comm: memcg_test Not tainted 5.9.0-rc2+ #12
Call Trace:
shrink_lruvec+0x49f/0x640
shrink_node+0x2a6/0x6f0
do_try_to_free_pages+0xe9/0x3e0
try_to_free_mem_cgroup_pages+0xef/0x1f0
try_charge+0x2c1/0x750
mem_cgroup_charge+0xd7/0x240
__add_to_page_cache_locked+0x2fd/0x370
add_to_page_cache_lru+0x4a/0xc0
pagecache_get_page+0x10b/0x2f0
filemap_fault+0x661/0xad0
ext4_filemap_fault+0x2c/0x40
__do_fault+0x4d/0xf9
handle_mm_fault+0x1080/0x1790
It only happens on our 1-vcpu instances, because there's no chance for
oom reaper to run to reclaim the to-be-killed process.
Add a cond_resched() at the upper shrink_node_memcgs() to solve this
issue, this will mean that we will get a scheduling point for each memcg
in the reclaimed hierarchy without any dependency on the reclaimable
memory in that memcg thus making it more predictable.
Suggested-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Xunlei Pang <xlpang@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Chris Down <chris@chrisdown.name>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Link: http://lkml.kernel.org/r/1598495549-67324-1-git-send-email-xlpang@linux.alibaba.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The thp prefix is more frequently used than hpage and we should be
consistent between the various functions.
[akpm@linux-foundation.org: fix mm/migrate.c]
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Link: http://lkml.kernel.org/r/20200629151959.15779-6-willy@infradead.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Drop the repeated word "marked".
Change "time time" to "same time".
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Link: http://lkml.kernel.org/r/20200801173822.14973-14-rdunlap@infradead.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Now that workingset detection is implemented for anonymous LRU, we don't
need large inactive list to allow detecting frequently accessed pages
before they are reclaimed, anymore. This effectively reverts the
temporary measure put in by commit "mm/vmscan: make active/inactive ratio
as 1:1 for anon lru".
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Link: http://lkml.kernel.org/r/1595490560-15117-7-git-send-email-iamjoonsoo.kim@lge.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch implements workingset detection for anonymous LRU. All the
infrastructure is implemented by the previous patches so this patch just
activates the workingset detection by installing/retrieving the shadow
entry and adding refault calculation.
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Link: http://lkml.kernel.org/r/1595490560-15117-6-git-send-email-iamjoonsoo.kim@lge.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Workingset detection for anonymous page will be implemented in the
following patch and it requires to store the shadow entries into the
swapcache. This patch implements an infrastructure to store the shadow
entry in the swapcache.
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Link: http://lkml.kernel.org/r/1595490560-15117-5-git-send-email-iamjoonsoo.kim@lge.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
To prepare the workingset detection for anon LRU, this patch splits
workingset event counters for refault, activate and restore into anon and
file variants, as well as the refaults counter in struct lruvec.
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Link: http://lkml.kernel.org/r/1595490560-15117-4-git-send-email-iamjoonsoo.kim@lge.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In current implementation, newly created or swap-in anonymous page is
started on active list. Growing active list results in rebalancing
active/inactive list so old pages on active list are demoted to inactive
list. Hence, the page on active list isn't protected at all.
Following is an example of this situation.
Assume that 50 hot pages on active list. Numbers denote the number of
pages on active/inactive list (active | inactive).
1. 50 hot pages on active list
50(h) | 0
2. workload: 50 newly created (used-once) pages
50(uo) | 50(h)
3. workload: another 50 newly created (used-once) pages
50(uo) | 50(uo), swap-out 50(h)
This patch tries to fix this issue. Like as file LRU, newly created or
swap-in anonymous pages will be inserted to the inactive list. They are
promoted to active list if enough reference happens. This simple
modification changes the above example as following.
1. 50 hot pages on active list
50(h) | 0
2. workload: 50 newly created (used-once) pages
50(h) | 50(uo)
3. workload: another 50 newly created (used-once) pages
50(h) | 50(uo), swap-out 50(uo)
As you can see, hot pages on active list would be protected.
Note that, this implementation has a drawback that the page cannot be
promoted and will be swapped-out if re-access interval is greater than the
size of inactive list but less than the size of total(active+inactive).
To solve this potential issue, following patch will apply workingset
detection similar to the one that's already applied to file LRU.
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Link: http://lkml.kernel.org/r/1595490560-15117-3-git-send-email-iamjoonsoo.kim@lge.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "workingset protection/detection on the anonymous LRU list", v7.
* PROBLEM
In current implementation, newly created or swap-in anonymous page is
started on the active list. Growing the active list results in
rebalancing active/inactive list so old pages on the active list are
demoted to the inactive list. Hence, hot page on the active list isn't
protected at all.
Following is an example of this situation.
Assume that 50 hot pages on active list and system can contain total 100
pages. Numbers denote the number of pages on active/inactive list (active
| inactive). (h) stands for hot pages and (uo) stands for used-once
pages.
1. 50 hot pages on active list
50(h) | 0
2. workload: 50 newly created (used-once) pages
50(uo) | 50(h)
3. workload: another 50 newly created (used-once) pages
50(uo) | 50(uo), swap-out 50(h)
As we can see, hot pages are swapped-out and it would cause swap-in later.
* SOLUTION
Since this is what we want to avoid, this patchset implements workingset
protection. Like as the file LRU list, newly created or swap-in anonymous
page is started on the inactive list. Also, like as the file LRU list, if
enough reference happens, the page will be promoted. This simple
modification changes the above example as following.
1. 50 hot pages on active list
50(h) | 0
2. workload: 50 newly created (used-once) pages
50(h) | 50(uo)
3. workload: another 50 newly created (used-once) pages
50(h) | 50(uo), swap-out 50(uo)
hot pages remains in the active list. :)
* EXPERIMENT
I tested this scenario on my test bed and confirmed that this problem
happens on current implementation. I also checked that it is fixed by
this patchset.
* SUBJECT
workingset detection
* PROBLEM
Later part of the patchset implements the workingset detection for the
anonymous LRU list. There is a corner case that workingset protection
could cause thrashing. If we can avoid thrashing by workingset detection,
we can get the better performance.
Following is an example of thrashing due to the workingset protection.
1. 50 hot pages on active list
50(h) | 0
2. workload: 50 newly created (will be hot) pages
50(h) | 50(wh)
3. workload: another 50 newly created (used-once) pages
50(h) | 50(uo), swap-out 50(wh)
4. workload: 50 (will be hot) pages
50(h) | 50(wh), swap-in 50(wh)
5. workload: another 50 newly created (used-once) pages
50(h) | 50(uo), swap-out 50(wh)
6. repeat 4, 5
Without workingset detection, this kind of workload cannot be promoted and
thrashing happens forever.
* SOLUTION
Therefore, this patchset implements workingset detection. All the
infrastructure for workingset detecion is already implemented, so there is
not much work to do. First, extend workingset detection code to deal with
the anonymous LRU list. Then, make swap cache handles the exceptional
value for the shadow entry. Lastly, install/retrieve the shadow value
into/from the swap cache and check the refault distance.
* EXPERIMENT
I made a test program to imitates above scenario and confirmed that
problem exists. Then, I checked that this patchset fixes it.
My test setup is a virtual machine with 8 cpus and 6100MB memory. But,
the amount of the memory that the test program can use is about 280 MB.
This is because the system uses large ram-backed swap and large ramdisk to
capture the trace.
Test scenario is like as below.
1. allocate cold memory (512MB)
2. allocate hot-1 memory (96MB)
3. activate hot-1 memory (96MB)
4. allocate another hot-2 memory (96MB)
5. access cold memory (128MB)
6. access hot-2 memory (96MB)
7. repeat 5, 6
Since hot-1 memory (96MB) is on the active list, the inactive list can
contains roughly 190MB pages. hot-2 memory's re-access interval (96+128
MB) is more 190MB, so it cannot be promoted without workingset detection
and swap-in/out happens repeatedly. With this patchset, workingset
detection works and promotion happens. Therefore, swap-in/out occurs
less.
Here is the result. (average of 5 runs)
type swap-in swap-out
base 863240 989945
patch 681565 809273
As we can see, patched kernel do less swap-in/out.
* OVERALL TEST (ebizzy using modified random function)
ebizzy is the test program that main thread allocates lots of memory and
child threads access them randomly during the given times. Swap-in will
happen if allocated memory is larger than the system memory.
The random function that represents the zipf distribution is used to make
hot/cold memory. Hot/cold ratio is controlled by the parameter. If the
parameter is high, hot memory is accessed much larger than cold one. If
the parameter is low, the number of access on each memory would be
similar. I uses various parameters in order to show the effect of
patchset on various hot/cold ratio workload.
My test setup is a virtual machine with 8 cpus, 1024 MB memory and 5120 MB
ram swap.
Result format is as following.
param: 1-1024-0.1
- 1 (number of thread)
- 1024 (allocated memory size, MB)
- 0.1 (zipf distribution alpha,
0.1 works like as roughly uniform random,
1.3 works like as small portion of memory is hot and the others are cold)
pswpin: smaller is better
std: standard deviation
improvement: negative is better
* single thread
param pswpin std improvement
base 1-1024.0-0.1 14101983.40 79441.19
prot 1-1024.0-0.1 14065875.80 136413.01 ( -0.26 )
detect 1-1024.0-0.1 13910435.60 100804.82 ( -1.36 )
base 1-1024.0-0.7 7998368.80 43469.32
prot 1-1024.0-0.7 7622245.80 88318.74 ( -4.70 )
detect 1-1024.0-0.7 7618515.20 59742.07 ( -4.75 )
base 1-1024.0-1.3 1017400.80 38756.30
prot 1-1024.0-1.3 940464.60 29310.69 ( -7.56 )
detect 1-1024.0-1.3 945511.40 24579.52 ( -7.07 )
base 1-1280.0-0.1 22895541.40 50016.08
prot 1-1280.0-0.1 22860305.40 51952.37 ( -0.15 )
detect 1-1280.0-0.1 22705565.20 93380.35 ( -0.83 )
base 1-1280.0-0.7 13717645.60 46250.65
prot 1-1280.0-0.7 12935355.80 64754.43 ( -5.70 )
detect 1-1280.0-0.7 13040232.00 63304.00 ( -4.94 )
base 1-1280.0-1.3 1654251.40 4159.68
prot 1-1280.0-1.3 1522680.60 33673.50 ( -7.95 )
detect 1-1280.0-1.3 1599207.00 70327.89 ( -3.33 )
base 1-1536.0-0.1 31621775.40 31156.28
prot 1-1536.0-0.1 31540355.20 62241.36 ( -0.26 )
detect 1-1536.0-0.1 31420056.00 123831.27 ( -0.64 )
base 1-1536.0-0.7 19620760.60 60937.60
prot 1-1536.0-0.7 18337839.60 56102.58 ( -6.54 )
detect 1-1536.0-0.7 18599128.00 75289.48 ( -5.21 )
base 1-1536.0-1.3 2378142.40 20994.43
prot 1-1536.0-1.3 2166260.60 48455.46 ( -8.91 )
detect 1-1536.0-1.3 2183762.20 16883.24 ( -8.17 )
base 1-1792.0-0.1 40259714.80 90750.70
prot 1-1792.0-0.1 40053917.20 64509.47 ( -0.51 )
detect 1-1792.0-0.1 39949736.40 104989.64 ( -0.77 )
base 1-1792.0-0.7 25704884.40 69429.68
prot 1-1792.0-0.7 23937389.00 79945.60 ( -6.88 )
detect 1-1792.0-0.7 24271902.00 35044.30 ( -5.57 )
base 1-1792.0-1.3 3129497.00 32731.86
prot 1-1792.0-1.3 2796994.40 19017.26 ( -10.62 )
detect 1-1792.0-1.3 2886840.40 33938.82 ( -7.75 )
base 1-2048.0-0.1 48746924.40 50863.88
prot 1-2048.0-0.1 48631954.40 24537.30 ( -0.24 )
detect 1-2048.0-0.1 48509419.80 27085.34 ( -0.49 )
base 1-2048.0-0.7 32046424.40 78624.22
prot 1-2048.0-0.7 29764182.20 86002.26 ( -7.12 )
detect 1-2048.0-0.7 30250315.80 101282.14 ( -5.60 )
base 1-2048.0-1.3 3916723.60 24048.55
prot 1-2048.0-1.3 3490781.60 33292.61 ( -10.87 )
detect 1-2048.0-1.3 3585002.20 44942.04 ( -8.47 )
* multi thread
param pswpin std improvement
base 8-1024.0-0.1 16219822.60 329474.01
prot 8-1024.0-0.1 15959494.00 654597.45 ( -1.61 )
detect 8-1024.0-0.1 15773790.80 502275.25 ( -2.75 )
base 8-1024.0-0.7 9174107.80 537619.33
prot 8-1024.0-0.7 8571915.00 385230.08 ( -6.56 )
detect 8-1024.0-0.7 8489484.20 364683.00 ( -7.46 )
base 8-1024.0-1.3 1108495.60 83555.98
prot 8-1024.0-1.3 1038906.20 63465.20 ( -6.28 )
detect 8-1024.0-1.3 941817.80 32648.80 ( -15.04 )
base 8-1280.0-0.1 25776114.20 450480.45
prot 8-1280.0-0.1 25430847.00 465627.07 ( -1.34 )
detect 8-1280.0-0.1 25282555.00 465666.55 ( -1.91 )
base 8-1280.0-0.7 15218968.00 702007.69
prot 8-1280.0-0.7 13957947.80 492643.86 ( -8.29 )
detect 8-1280.0-0.7 14158331.20 238656.02 ( -6.97 )
base 8-1280.0-1.3 1792482.80 30512.90
prot 8-1280.0-1.3 1577686.40 34002.62 ( -11.98 )
detect 8-1280.0-1.3 1556133.00 22944.79 ( -13.19 )
base 8-1536.0-0.1 33923761.40 575455.85
prot 8-1536.0-0.1 32715766.20 300633.51 ( -3.56 )
detect 8-1536.0-0.1 33158477.40 117764.51 ( -2.26 )
base 8-1536.0-0.7 20628907.80 303851.34
prot 8-1536.0-0.7 19329511.20 341719.31 ( -6.30 )
detect 8-1536.0-0.7 20013934.00 385358.66 ( -2.98 )
base 8-1536.0-1.3 2588106.40 130769.20
prot 8-1536.0-1.3 2275222.40 89637.06 ( -12.09 )
detect 8-1536.0-1.3 2365008.40 124412.55 ( -8.62 )
base 8-1792.0-0.1 43328279.20 946469.12
prot 8-1792.0-0.1 41481980.80 525690.89 ( -4.26 )
detect 8-1792.0-0.1 41713944.60 406798.93 ( -3.73 )
base 8-1792.0-0.7 27155647.40 536253.57
prot 8-1792.0-0.7 24989406.80 502734.52 ( -7.98 )
detect 8-1792.0-0.7 25524806.40 263237.87 ( -6.01 )
base 8-1792.0-1.3 3260372.80 137907.92
prot 8-1792.0-1.3 2879187.80 63597.26 ( -11.69 )
detect 8-1792.0-1.3 2892962.20 33229.13 ( -11.27 )
base 8-2048.0-0.1 50583989.80 710121.48
prot 8-2048.0-0.1 49599984.40 228782.42 ( -1.95 )
detect 8-2048.0-0.1 50578596.00 660971.66 ( -0.01 )
base 8-2048.0-0.7 33765479.60 812659.55
prot 8-2048.0-0.7 30767021.20 462907.24 ( -8.88 )
detect 8-2048.0-0.7 32213068.80 211884.24 ( -4.60 )
base 8-2048.0-1.3 3941675.80 28436.45
prot 8-2048.0-1.3 3538742.40 76856.08 ( -10.22 )
detect 8-2048.0-1.3 3579397.80 58630.95 ( -9.19 )
As we can see, all the cases show improvement. Especially, test case with
zipf distribution 1.3 show more improvements. It means that if there is a
hot/cold tendency in anon pages, this patchset works better.
This patch (of 6):
Current implementation of LRU management for anonymous page has some
problems. Most important one is that it doesn't protect the workingset,
that is, pages on the active LRU list. Although, this problem will be
fixed in the following patchset, the preparation is required and this
patch does it.
What following patch does is to implement workingset protection. After
the following patchset, newly created or swap-in pages will start their
lifetime on the inactive list. If inactive list is too small, there is
not enough chance to be referenced and the page cannot become the
workingset.
In order to provide the newly anonymous or swap-in pages enough chance to
be referenced again, this patch makes active/inactive LRU ratio as 1:1.
This is just a temporary measure. Later patch in the series introduces
workingset detection for anonymous LRU that will be used to better decide
if pages should start on the active and inactive list. Afterwards this
patch is effectively reverted.
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Matthew Wilcox <willy@infradead.org>
Link: http://lkml.kernel.org/r/1595490560-15117-1-git-send-email-iamjoonsoo.kim@lge.com
Link: http://lkml.kernel.org/r/1595490560-15117-2-git-send-email-iamjoonsoo.kim@lge.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The vmstat pgrefill is useful together with pgscan and pgsteal stats to
measure the reclaim efficiency. However vmstat's pgrefill is not updated
consistently at system level. It gets updated for both global and memcg
reclaim however pgscan and pgsteal are updated for only global reclaim.
So, update pgrefill only for global reclaim. If someone is interested in
the stats representing both system level as well as memcg level reclaim,
then consult the root memcg's memory.stat instead of /proc/vmstat.
Signed-off-by: Shakeel Butt <shakeelb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Yafang Shao <laoar.shao@gmail.com>
Acked-by: Roman Gushchin <guro@fb.com>
Acked-by: Chris Down <chris@chrisdown.name>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Link: http://lkml.kernel.org/r/20200711011459.1159929-1-shakeelb@google.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The global variable "vm_total_pages" is a relic from older days. There is
only a single user that reads the variable - build_all_zonelists() - and
the first thing it does is update it.
Use a local variable in build_all_zonelists() instead and remove the
global variable.
Signed-off-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Reviewed-by: Mike Rapoport <rppt@linux.ibm.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Minchan Kim <minchan@kernel.org>
Link: http://lkml.kernel.org/r/20200619132410.23859-2-david@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When an outside process lowers one of the memory limits of a cgroup (or
uses the force_empty knob in cgroup1), direct reclaim is performed in the
context of the write(), in order to directly enforce the new limit and
have it being met by the time the write() returns.
Currently, this reclaim activity is accounted as memory pressure in the
cgroup that the writer(!) belongs to. This is unexpected. It
specifically causes problems for senpai
(https://github.com/facebookincubator/senpai), which is an agent that
routinely adjusts the memory limits and performs associated reclaim work
in tens or even hundreds of cgroups running on the host. The cgroup that
senpai is running in itself will report elevated levels of memory
pressure, even though it itself is under no memory shortage or any sort of
distress.
Move the psi annotation from the central cgroup reclaim function to
callsites in the allocation context, and thereby no longer count any
limit-setting reclaim as memory pressure. If the newly set limit causes
the workload inside the cgroup into direct reclaim, that of course will
continue to count as memory pressure.
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Reviewed-by: Roman Gushchin <guro@fb.com>
Acked-by: Chris Down <chris@chrisdown.name>
Acked-by: Michal Hocko <mhocko@suse.com>
Link: http://lkml.kernel.org/r/20200728135210.379885-2-hannes@cmpxchg.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mem_cgroup_protected currently is both used to set effective low and min
and return a mem_cgroup_protection based on the result. As a user, this
can be a little unexpected: it appears to be a simple predicate function,
if not for the big warning in the comment above about the order in which
it must be executed.
This change makes it so that we separate the state mutations from the
actual protection checks, which makes it more obvious where we need to be
careful mutating internal state, and where we are simply checking and
don't need to worry about that.
[mhocko@suse.com - don't check protection on root memcgs]
Suggested-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Chris Down <chris@chrisdown.name>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Yafang Shao <laoar.shao@gmail.com>
Link: http://lkml.kernel.org/r/ff3f915097fcee9f6d7041c084ef92d16aaeb56a.1594638158.git.chris@chrisdown.name
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "mm, memcg: memory.{low,min} reclaim fix & cleanup", v4.
This series contains a fix for a edge case in my earlier protection
calculation patches, and a patch to make the area overall a little more
robust to hopefully help avoid this in future.
This patch (of 2):
A cgroup can have both memory protection and a memory limit to isolate it
from its siblings in both directions - for example, to prevent it from
being shrunk below 2G under high pressure from outside, but also from
growing beyond 4G under low pressure.
Commit 9783aa9917 ("mm, memcg: proportional memory.{low,min} reclaim")
implemented proportional scan pressure so that multiple siblings in excess
of their protection settings don't get reclaimed equally but instead in
accordance to their unprotected portion.
During limit reclaim, this proportionality shouldn't apply of course:
there is no competition, all pressure is from within the cgroup and should
be applied as such. Reclaim should operate at full efficiency.
However, mem_cgroup_protected() never expected anybody to look at the
effective protection values when it indicated that the cgroup is above its
protection. As a result, a query during limit reclaim may return stale
protection values that were calculated by a previous reclaim cycle in
which the cgroup did have siblings.
When this happens, reclaim is unnecessarily hesitant and potentially slow
to meet the desired limit. In theory this could lead to premature OOM
kills, although it's not obvious this has occurred in practice.
Workaround the problem by special casing reclaim roots in
mem_cgroup_protection. These memcgs are never participating in the
reclaim protection because the reclaim is internal.
We have to ignore effective protection values for reclaim roots because
mem_cgroup_protected might be called from racing reclaim contexts with
different roots. Calculation is relying on root -> leaf tree traversal
therefore top-down reclaim protection invariants should hold. The only
exception is the reclaim root which should have effective protection set
to 0 but that would be problematic for the following setup:
Let's have global and A's reclaim in parallel:
|
A (low=2G, usage = 3G, max = 3G, children_low_usage = 1.5G)
|\
| C (low = 1G, usage = 2.5G)
B (low = 1G, usage = 0.5G)
for A reclaim we have
B.elow = B.low
C.elow = C.low
For the global reclaim
A.elow = A.low
B.elow = min(B.usage, B.low) because children_low_usage <= A.elow
C.elow = min(C.usage, C.low)
With the effective values resetting we have A reclaim
A.elow = 0
B.elow = B.low
C.elow = C.low
and global reclaim could see the above and then
B.elow = C.elow = 0 because children_low_usage > A.elow
Which means that protected memcgs would get reclaimed.
In future we would like to make mem_cgroup_protected more robust against
racing reclaim contexts but that is likely more complex solution than this
simple workaround.
[hannes@cmpxchg.org - large part of the changelog]
[mhocko@suse.com - workaround explanation]
[chris@chrisdown.name - retitle]
Fixes: 9783aa9917 ("mm, memcg: proportional memory.{low,min} reclaim")
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Signed-off-by: Chris Down <chris@chrisdown.name>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Chris Down <chris@chrisdown.name>
Acked-by: Roman Gushchin <guro@fb.com>
Link: http://lkml.kernel.org/r/cover.1594638158.git.chris@chrisdown.name
Link: http://lkml.kernel.org/r/044fb8ecffd001c7905d27c0c2ad998069fdc396.1594638158.git.chris@chrisdown.name
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In order to prepare for per-object slab memory accounting, convert
NR_SLAB_RECLAIMABLE and NR_SLAB_UNRECLAIMABLE vmstat items to bytes.
To make it obvious, rename them to NR_SLAB_RECLAIMABLE_B and
NR_SLAB_UNRECLAIMABLE_B (similar to NR_KERNEL_STACK_KB).
Internally global and per-node counters are stored in pages, however memcg
and lruvec counters are stored in bytes. This scheme may look weird, but
only for now. As soon as slab pages will be shared between multiple
cgroups, global and node counters will reflect the total number of slab
pages. However memcg and lruvec counters will be used for per-memcg slab
memory tracking, which will take separate kernel objects in the account.
Keeping global and node counters in pages helps to avoid additional
overhead.
The size of slab memory shouldn't exceed 4Gb on 32-bit machines, so it
will fit into atomic_long_t we use for vmstats.
Signed-off-by: Roman Gushchin <guro@fb.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Link: http://lkml.kernel.org/r/20200623174037.3951353-4-guro@fb.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "fix for "mm: balance LRU lists based on relative
thrashing" patchset"
This patchset fixes some problems of the patchset, "mm: balance LRU
lists based on relative thrashing", which is now merged on the mainline.
Patch "mm: workingset: let cache workingset challenge anon fix" is the
result of discussion with Johannes. See following link.
http://lkml.kernel.org/r/20200520232525.798933-6-hannes@cmpxchg.org
And, the other two are minor things which are found when I try to rebase
my patchset.
This patch (of 3):
After ("mm: workingset: let cache workingset challenge anon fix"), we
compare refault distances to active_file + anon. But age of the
non-resident information is only driven by the file LRU. As a result,
we may overestimate the recency of any incoming refaults and activate
them too eagerly, causing unnecessary LRU churn in certain situations.
Make anon aging drive nonresident age as well to address that.
Link: http://lkml.kernel.org/r/1592288204-27734-1-git-send-email-iamjoonsoo.kim@lge.com
Link: http://lkml.kernel.org/r/1592288204-27734-2-git-send-email-iamjoonsoo.kim@lge.com
Fixes: 34e58cac6d ("mm: workingset: let cache workingset challenge anon")
Reported-by: Joonsoo Kim <js1304@gmail.com>
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There are some typos, fix them.
s/regsitration/registration
s/santity/sanity
s/decremeting/decrementing
Signed-off-by: Ethon Paul <ethp@qq.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Ralph Campbell <rcampbell@nvidia.com>
Link: http://lkml.kernel.org/r/20200411071544.16222-1-ethp@qq.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When LRU cost only shows up on one list, we abruptly stop scanning that
list altogether. That's an extreme reaction: by the time the other list
starts thrashing and the pendulum swings back, we may have no recent age
information on the first list anymore, and we could have significant
latencies until the scanner has caught up.
Soften this change in the feedback system by ensuring that no list
receives less than a third of overall pressure, and only distribute the
other 66% according to LRU cost. This ensures that we maintain a minimum
rate of aging on the entire workingset while it's being pressured, while
still allowing a generous rate of convergence when the relative sizes of
the lists need to adjust.
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Rik van Riel <riel@surriel.com>
Link: http://lkml.kernel.org/r/20200520232525.798933-15-hannes@cmpxchg.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The VM tries to balance reclaim pressure between anon and file so as to
reduce the amount of IO incurred due to the memory shortage. It already
counts refaults and swapins, but in addition it should also count
writepage calls during reclaim.
For swap, this is obvious: it's IO that wouldn't have occurred if the
anonymous memory hadn't been under memory pressure. From a relative
balancing point of view this makes sense as well: even if anon is cold and
reclaimable, a cache that isn't thrashing may have equally cold pages that
don't require IO to reclaim.
For file writeback, it's trickier: some of the reclaim writepage IO would
have likely occurred anyway due to dirty expiration. But not all of it -
premature writeback reduces batching and generates additional writes.
Since the flushers are already woken up by the time the VM starts writing
cache pages one by one, let's assume that we'e likely causing writes that
wouldn't have happened without memory pressure. In addition, the per-page
cost of IO would have probably been much cheaper if written in larger
batches from the flusher thread rather than the single-page-writes from
kswapd.
For our purposes - getting the trend right to accelerate convergence on a
stable state that doesn't require paging at all - this is sufficiently
accurate. If we later wanted to optimize for sustained thrashing, we can
still refine the measurements.
Count all writepage calls from kswapd as IO cost toward the LRU that the
page belongs to.
Why do this dynamically? Don't we know in advance that anon pages require
IO to reclaim, and so could build in a static bias?
First, scanning is not the same as reclaiming. If all the anon pages are
referenced, we may not swap for a while just because we're scanning the
anon list. During this time, however, it's important that we age
anonymous memory and the page cache at the same rate so that their
hot-cold gradients are comparable. Everything else being equal, we still
want to reclaim the coldest memory overall.
Second, we keep copies in swap unless the page changes. If there is
swap-backed data that's mostly read (tmpfs file) and has been swapped out
before, we can reclaim it without incurring additional IO.
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Rik van Riel <riel@surriel.com>
Link: http://lkml.kernel.org/r/20200520232525.798933-14-hannes@cmpxchg.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We split the LRU lists into anon and file, and we rebalance the scan
pressure between them when one of them begins thrashing: if the file cache
experiences workingset refaults, we increase the pressure on anonymous
pages; if the workload is stalled on swapins, we increase the pressure on
the file cache instead.
With cgroups and their nested LRU lists, we currently don't do this
correctly. While recursive cgroup reclaim establishes a relative LRU
order among the pages of all involved cgroups, LRU pressure balancing is
done on an individual cgroup LRU level. As a result, when one cgroup is
thrashing on the filesystem cache while a sibling may have cold anonymous
pages, pressure doesn't get equalized between them.
This patch moves LRU balancing decision to the root of reclaim - the same
level where the LRU order is established.
It does this by tracking LRU cost recursively, so that every level of the
cgroup tree knows the aggregate LRU cost of all memory within its domain.
When the page scanner calculates the scan balance for any given individual
cgroup's LRU list, it uses the values from the ancestor cgroup that
initiated the reclaim cycle.
If one sibling is then thrashing on the cache, it will tip the pressure
balance inside its ancestors, and the next hierarchical reclaim iteration
will go more after the anon pages in the tree.
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Rik van Riel <riel@surriel.com>
Link: http://lkml.kernel.org/r/20200520232525.798933-13-hannes@cmpxchg.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Since the LRUs were split into anon and file lists, the VM has been
balancing between page cache and anonymous pages based on per-list ratios
of scanned vs. rotated pages. In most cases that tips page reclaim
towards the list that is easier to reclaim and has the fewest actively
used pages, but there are a few problems with it:
1. Refaults and LRU rotations are weighted the same way, even though
one costs IO and the other costs a bit of CPU.
2. The less we scan an LRU list based on already observed rotations,
the more we increase the sampling interval for new references, and
rotations become even more likely on that list. This can enter a
death spiral in which we stop looking at one list completely until
the other one is all but annihilated by page reclaim.
Since commit a528910e12 ("mm: thrash detection-based file cache sizing")
we have refault detection for the page cache. Along with swapin events,
they are good indicators of when the file or anon list, respectively, is
too small for its workingset and needs to grow.
For example, if the page cache is thrashing, the cache pages need more
time in memory, while there may be colder pages on the anonymous list.
Likewise, if swapped pages are faulting back in, it indicates that we
reclaim anonymous pages too aggressively and should back off.
Replace LRU rotations with refaults and swapins as the basis for relative
reclaim cost of the two LRUs. This will have the VM target list balances
that incur the least amount of IO on aggregate.
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Rik van Riel <riel@surriel.com>
Link: http://lkml.kernel.org/r/20200520232525.798933-12-hannes@cmpxchg.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When shrinking the active file list we rotate referenced pages only when
they're in an executable mapping. The others get deactivated. When it
comes to balancing scan pressure, though, we count all referenced pages as
rotated, even the deactivated ones. Yet they do not carry the same cost
to the system: the deactivated page *might* refault later on, but the
deactivation is tangible progress toward freeing pages; rotations on the
other hand cost time and effort without getting any closer to freeing
memory.
Don't treat both events as equal. The following patch will hook up LRU
balancing to cache and anon refaults, which are a much more concrete cost
signal for reclaiming one list over the other. Thus, remove the maybe-IO
cost bias from page references, and only note the CPU cost for actual
rotations that prevent the pages from getting reclaimed.
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Minchan Kim <minchan@kernel.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Rik van Riel <riel@surriel.com>
Link: http://lkml.kernel.org/r/20200520232525.798933-11-hannes@cmpxchg.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently, scan pressure between the anon and file LRU lists is balanced
based on a mixture of reclaim efficiency and a somewhat vague notion of
"value" of having certain pages in memory over others. That concept of
value is problematic, because it has caused us to count any event that
remotely makes one LRU list more or less preferrable for reclaim, even
when these events are not directly comparable and impose very different
costs on the system. One example is referenced file pages that we still
deactivate and referenced anonymous pages that we actually rotate back to
the head of the list.
There is also conceptual overlap with the LRU algorithm itself. By
rotating recently used pages instead of reclaiming them, the algorithm
already biases the applied scan pressure based on page value. Thus, when
rebalancing scan pressure due to rotations, we should think of reclaim
cost, and leave assessing the page value to the LRU algorithm.
Lastly, considering both value-increasing as well as value-decreasing
events can sometimes cause the same type of event to be counted twice,
i.e. how rotating a page increases the LRU value, while reclaiming it
succesfully decreases the value. In itself this will balance out fine,
but it quietly skews the impact of events that are only recorded once.
The abstract metric of "value", the murky relationship with the LRU
algorithm, and accounting both negative and positive events make the
current pressure balancing model hard to reason about and modify.
This patch switches to a balancing model of accounting the concrete,
actually observed cost of reclaiming one LRU over another. For now, that
cost includes pages that are scanned but rotated back to the list head.
Subsequent patches will add consideration for IO caused by refaulting of
recently evicted pages.
Replace struct zone_reclaim_stat with two cost counters in the lruvec, and
make everything that affects cost go through a new lru_note_cost()
function.
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Rik van Riel <riel@surriel.com>
Link: http://lkml.kernel.org/r/20200520232525.798933-9-hannes@cmpxchg.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When we calculate the relative scan pressure between the anon and file LRU
lists, we have to assume that reclaim_stat can contain zeroes. To avoid
div0 crashes, we add 1 to all denominators like so:
anon_prio = swappiness;
file_prio = 200 - anon_prio;
[...]
/*
* The amount of pressure on anon vs file pages is inversely
* proportional to the fraction of recently scanned pages on
* each list that were recently referenced and in active use.
*/
ap = anon_prio * (reclaim_stat->recent_scanned[0] + 1);
ap /= reclaim_stat->recent_rotated[0] + 1;
fp = file_prio * (reclaim_stat->recent_scanned[1] + 1);
fp /= reclaim_stat->recent_rotated[1] + 1;
spin_unlock_irq(&pgdat->lru_lock);
fraction[0] = ap;
fraction[1] = fp;
denominator = ap + fp + 1;
While reclaim_stat can contain 0, it's not actually possible for ap + fp
to be 0. One of anon_prio or file_prio could be zero, but they must still
add up to 200. And the reclaim_stat fraction, due to the +1 in there, is
always at least 1. So if one of the two numerators is 0, the other one
can't be. ap + fp is always at least 1. Drop the + 1.
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Rik van Riel <riel@surriel.com>
Link: http://lkml.kernel.org/r/20200520232525.798933-8-hannes@cmpxchg.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
With the advent of fast random IO devices (SSDs, PMEM) and in-memory swap
devices such as zswap, it's possible for swap to be much faster than
filesystems, and for swapping to be preferable over thrashing filesystem
caches.
Allow setting swappiness - which defines the rough relative IO cost of
cache misses between page cache and swap-backed pages - to reflect such
situations by making the swap-preferred range configurable.
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Rik van Riel <riel@surriel.com>
Link: http://lkml.kernel.org/r/20200520232525.798933-4-hannes@cmpxchg.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Having statistics on pages scanned and pages reclaimed for both anon and
file pages makes it easier to evaluate changes to LRU balancing.
While at it, clean up the stat-keeping mess for isolation, putback,
reclaim stats etc. a bit: first the physical LRU operation (isolation and
putback), followed by vmstats, reclaim_stats, and then vm events.
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Rik van Riel <riel@surriel.com>
Link: http://lkml.kernel.org/r/20200520232525.798933-3-hannes@cmpxchg.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
try_to_compact_zone() has been replaced by try_to_compact_pages(), which
is necessary to be updated in the comment of should_continue_reclaim().
Signed-off-by: Qiwu Chen <chenqiwu@xiaomi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20200501034907.22991-1-chenqiwu@xiaomi.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
commit 3c710c1ad1 ("mm, vmscan extract shrink_page_list reclaim counters
into a struct") changed data type for the function, so changing return
type for funciton and its caller.
Signed-off-by: Vaneet Narang <v.narang@samsung.com>
Signed-off-by: Maninder Singh <maninder1.s@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Amit Sahrawat <a.sahrawat@samsung.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Link: http://lkml.kernel.org/r/1588168259-25604-1-git-send-email-maninder1.s@samsung.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Fix an nr_isolate_* mismatch problem between cma and dirty lazyfree pages.
If try_to_unmap_one is used for reclaim and it detects a dirty lazyfree
page, then the lazyfree page is changed to a normal anon page having
SwapBacked by commit 802a3a92ad ("mm: reclaim MADV_FREE pages"). Even
with the change, reclaim context correctly counts isolated files because
it uses is_file_lru to distinguish file. And the change to anon is not
happened if try_to_unmap_one is used for migration. So migration context
like compaction also correctly counts isolated files even though it uses
page_is_file_lru insted of is_file_lru. Recently page_is_file_cache was
renamed to page_is_file_lru by commit 9de4f22a60 ("mm: code cleanup for
MADV_FREE").
But the nr_isolate_* mismatch problem happens on cma alloc. There is
reclaim_clean_pages_from_list which is being used only by cma. It was
introduced by commit 02c6de8d75 ("mm: cma: discard clean pages during
contiguous allocation instead of migration") to reclaim clean file pages
without migration. The cma alloc uses both reclaim_clean_pages_from_list
and migrate_pages, and it uses page_is_file_lru to count isolated files.
If there are dirty lazyfree pages allocated from cma memory region, the
pages are counted as isolated file at the beginging but are counted as
isolated anon after finished.
Mem-Info:
Node 0 active_anon:3045904kB inactive_anon:611448kB active_file:14892kB inactive_file:205636kB unevictable:10416kB isolated(anon):0kB isolated(file):37664kB mapped:630216kB dirty:384kB writeback:0kB shmem:42576kB writeback_tmp:0kB unstable:0kB all_unreclaimable? no
Like log above, there were too much isolated files, 37664kB, which
triggers too_many_isolated in reclaim even when there is no actually
isolated file in system wide. It could be reproducible by running two
programs, writing on MADV_FREE page and doing cma alloc, respectively.
Although isolated anon is 0, I found that the internal value of isolated
anon was the negative value of isolated file.
Fix this by compensating the isolated count for both LRU lists. Count
non-discarded lazyfree pages in shrink_page_list, then compensate the
counted number in reclaim_clean_pages_from_list.
Reported-by: Yong-Taek Lee <ytk.lee@samsung.com>
Suggested-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Jaewon Kim <jaewon31.kim@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Minchan Kim <minchan@kernel.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Michal Nazarewicz <mina86@mina86.com>
Cc: Shaohua Li <shli@fb.com>
Link: http://lkml.kernel.org/r/20200426011718.30246-1-jaewon31.kim@samsung.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We already defined the helper update_lru_size().
Let's use this to reduce code duplication.
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Baoquan He <bhe@redhat.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Link: http://lkml.kernel.org/r/20200331221550.1011-1-richard.weiyang@gmail.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
None of the three callers of get_compound_page_dtor() want to know the
value; they just want to call the function. Replace it with
destroy_compound_page() which calls the dtor for them.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Link: http://lkml.kernel.org/r/20200517105051.9352-1-willy@infradead.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
classzone_idx is just different name for high_zoneidx now. So, integrate
them and add some comment to struct alloc_context in order to reduce
future confusion about the meaning of this variable.
The accessor, ac_classzone_idx() is also removed since it isn't needed
after integration.
In addition to integration, this patch also renames high_zoneidx to
highest_zoneidx since it represents more precise meaning.
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Baoquan He <bhe@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Ye Xiaolong <xiaolong.ye@intel.com>
Link: http://lkml.kernel.org/r/1587095923-7515-3-git-send-email-iamjoonsoo.kim@lge.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
PF_LESS_THROTTLE exists for loop-back nfsd (and a similar need in the
loop block driver and callers of prctl(PR_SET_IO_FLUSHER)), where a
daemon needs to write to one bdi (the final bdi) in order to free up
writes queued to another bdi (the client bdi).
The daemon sets PF_LESS_THROTTLE and gets a larger allowance of dirty
pages, so that it can still dirty pages after other processses have been
throttled. The purpose of this is to avoid deadlock that happen when
the PF_LESS_THROTTLE process must write for any dirty pages to be freed,
but it is being thottled and cannot write.
This approach was designed when all threads were blocked equally,
independently on which device they were writing to, or how fast it was.
Since that time the writeback algorithm has changed substantially with
different threads getting different allowances based on non-trivial
heuristics. This means the simple "add 25%" heuristic is no longer
reliable.
The important issue is not that the daemon needs a *larger* dirty page
allowance, but that it needs a *private* dirty page allowance, so that
dirty pages for the "client" bdi that it is helping to clear (the bdi
for an NFS filesystem or loop block device etc) do not affect the
throttling of the daemon writing to the "final" bdi.
This patch changes the heuristic so that the task is not throttled when
the bdi it is writing to has a dirty page count below below (or equal
to) the free-run threshold for that bdi. This ensures it will always be
able to have some pages in flight, and so will not deadlock.
In a steady-state, it is expected that PF_LOCAL_THROTTLE tasks might
still be throttled by global threshold, but that is acceptable as it is
only the deadlock state that is interesting for this flag.
This approach of "only throttle when target bdi is busy" is consistent
with the other use of PF_LESS_THROTTLE in current_may_throttle(), were
it causes attention to be focussed only on the target bdi.
So this patch
- renames PF_LESS_THROTTLE to PF_LOCAL_THROTTLE,
- removes the 25% bonus that that flag gives, and
- If PF_LOCAL_THROTTLE is set, don't delay at all unless the
global and the local free-run thresholds are exceeded.
Note that previously realtime threads were treated the same as
PF_LESS_THROTTLE threads. This patch does *not* change the behvaiour
for real-time threads, so it is now different from the behaviour of nfsd
and loop tasks. I don't know what is wanted for realtime.
[akpm@linux-foundation.org: coding style fixes]
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Chuck Lever <chuck.lever@oracle.com> [nfsd]
Cc: Christoph Hellwig <hch@lst.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Trond Myklebust <trond.myklebust@hammerspace.com>
Link: http://lkml.kernel.org/r/87ftbf7gs3.fsf@notabene.neil.brown.name
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Since commit a9e7c39fa9 ("mm/vmscan.c: remove 7th argument of
isolate_lru_pages()"), the explanation of 'mode' argument has been
unnecessary. Let's remove it.
Signed-off-by: Qiwu Chen <chenqiwu@xiaomi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20200501090346.2894-1-chenqiwu@xiaomi.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Some comments for MADV_FREE is revised and added to help people understand
the MADV_FREE code, especially the page flag, PG_swapbacked. This makes
page_is_file_cache() isn't consistent with its comments. So the function
is renamed to page_is_file_lru() to make them consistent again. All these
are put in one patch as one logical change.
Suggested-by: David Hildenbrand <david@redhat.com>
Suggested-by: Johannes Weiner <hannes@cmpxchg.org>
Suggested-by: David Rientjes <rientjes@google.com>
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Michal Hocko <mhocko@kernel.org>
Acked-by: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Rik van Riel <riel@surriel.com>
Link: http://lkml.kernel.org/r/20200317100342.2730705-1-ying.huang@intel.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
sc->memcg_low_skipped resets skipped_deactivate to 0 but this is not
needed as this code path is never reachable with skipped_deactivate != 0
due to previous sc->skipped_deactivate branch.
[mhocko@kernel.org: rewrite changelog]
Signed-off-by: Mateusz Nosek <mateusznosek0@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Link: http://lkml.kernel.org/r/20200319165938.23354-1-mateusznosek0@gmail.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This gives some size improvement:
$size mm/vmscan.o (before)
text data bss dec hex filename
53670 24123 12 77805 12fed mm/vmscan.o
$size mm/vmscan.o (after)
text data bss dec hex filename
53648 24123 12 77783 12fd7 mm/vmscan.o
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/Message-ID:
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Previously 0 was assigned to variable 'lruvec_size', but the variable was
never read later. So the assignment can be removed.
Fixes: f87bccde6a ("mm/vmscan: remove unused lru_pages argument")
Signed-off-by: Mateusz Nosek <mateusznosek0@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Link: http://lkml.kernel.org/r/20200229214022.11853-1-mateusznosek0@gmail.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
pgdat->kswapd_classzone_idx could be accessed concurrently in
wakeup_kswapd(). Plain writes and reads without any lock protection
result in data races. Fix them by adding a pair of READ|WRITE_ONCE() as
well as saving a branch (compilers might well optimize the original code
in an unintentional way anyway). While at it, also take care of
pgdat->kswapd_order and non-kswapd threads in allow_direct_reclaim(). The
data races were reported by KCSAN,
BUG: KCSAN: data-race in wakeup_kswapd / wakeup_kswapd
write to 0xffff9f427ffff2dc of 4 bytes by task 7454 on cpu 13:
wakeup_kswapd+0xf1/0x400
wakeup_kswapd at mm/vmscan.c:3967
wake_all_kswapds+0x59/0xc0
wake_all_kswapds at mm/page_alloc.c:4241
__alloc_pages_slowpath+0xdcc/0x1290
__alloc_pages_slowpath at mm/page_alloc.c:4512
__alloc_pages_nodemask+0x3bb/0x450
alloc_pages_vma+0x8a/0x2c0
do_anonymous_page+0x16e/0x6f0
__handle_mm_fault+0xcd5/0xd40
handle_mm_fault+0xfc/0x2f0
do_page_fault+0x263/0x6f9
page_fault+0x34/0x40
1 lock held by mtest01/7454:
#0: ffff9f425afe8808 (&mm->mmap_sem#2){++++}, at:
do_page_fault+0x143/0x6f9
do_user_addr_fault at arch/x86/mm/fault.c:1405
(inlined by) do_page_fault at arch/x86/mm/fault.c:1539
irq event stamp: 6944085
count_memcg_event_mm+0x1a6/0x270
count_memcg_event_mm+0x119/0x270
__do_softirq+0x34c/0x57c
irq_exit+0xa2/0xc0
read to 0xffff9f427ffff2dc of 4 bytes by task 7472 on cpu 38:
wakeup_kswapd+0xc8/0x400
wake_all_kswapds+0x59/0xc0
__alloc_pages_slowpath+0xdcc/0x1290
__alloc_pages_nodemask+0x3bb/0x450
alloc_pages_vma+0x8a/0x2c0
do_anonymous_page+0x16e/0x6f0
__handle_mm_fault+0xcd5/0xd40
handle_mm_fault+0xfc/0x2f0
do_page_fault+0x263/0x6f9
page_fault+0x34/0x40
1 lock held by mtest01/7472:
#0: ffff9f425a9ac148 (&mm->mmap_sem#2){++++}, at:
do_page_fault+0x143/0x6f9
irq event stamp: 6793561
count_memcg_event_mm+0x1a6/0x270
count_memcg_event_mm+0x119/0x270
__do_softirq+0x34c/0x57c
irq_exit+0xa2/0xc0
BUG: KCSAN: data-race in kswapd / wakeup_kswapd
write to 0xffff90973ffff2dc of 4 bytes by task 820 on cpu 6:
kswapd+0x27c/0x8d0
kthread+0x1e0/0x200
ret_from_fork+0x27/0x50
read to 0xffff90973ffff2dc of 4 bytes by task 6299 on cpu 0:
wakeup_kswapd+0xf3/0x450
wake_all_kswapds+0x59/0xc0
__alloc_pages_slowpath+0xdcc/0x1290
__alloc_pages_nodemask+0x3bb/0x450
alloc_pages_vma+0x8a/0x2c0
do_anonymous_page+0x170/0x700
__handle_mm_fault+0xc9f/0xd00
handle_mm_fault+0xfc/0x2f0
do_page_fault+0x263/0x6f9
page_fault+0x34/0x40
Signed-off-by: Qian Cai <cai@lca.pw>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Marco Elver <elver@google.com>
Cc: Matthew Wilcox <willy@infradead.org>
Link: http://lkml.kernel.org/r/1582749472-5171-1-git-send-email-cai@lca.pw
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
kswapd kernel thread starts either with a CPU affinity set to the full cpu
mask of its target node or without any affinity at all if the node is
CPUless. There is a cpu hotplug callback (kswapd_cpu_online) that
implements an elaborate way to update this mask when a cpu is onlined.
It is not really clear whether there is any actual benefit from this
scheme. Completely CPU-less NUMA nodes rarely gain a new CPU during
runtime. Drop the code for that reason. If there is a real usecase then
we can resurrect and simplify the code.
[mhocko@suse.com rewrite changelog]
Suggested-by: Michal Hocko <mhocko@suse.org>
Signed-off-by: Wei Yang <richardw.yang@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: David Rientjes <rientjes@google.com>
Link: http://lkml.kernel.org/r/20200218224422.3407-1-richardw.yang@linux.intel.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The commit 98fa15f34c ("mm: replace all open encodings for
NUMA_NO_NODE") did the replacement across the kernel tree, but we got
some more in vmscan.c since then.
Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Acked-by: David Rientjes <rientjes@google.com>
Link: http://lkml.kernel.org/r/1581568298-45317-1-git-send-email-yang.shi@linux.alibaba.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When backporting commit 9c4e6b1a70 ("mm, mlock, vmscan: no more skipping
pagevecs") to our 4.9 kernel, our test bench noticed around 10% down with
a couple of vm-scalability's test cases (lru-file-readonce,
lru-file-readtwice and lru-file-mmap-read). I didn't see that much down
on my VM (32c-64g-2nodes). It might be caused by the test configuration,
which is 32c-256g with NUMA disabled and the tests were run in root memcg,
so the tests actually stress only one inactive and active lru. It sounds
not very usual in mordern production environment.
That commit did two major changes:
1. Call page_evictable()
2. Use smp_mb to force the PG_lru set visible
It looks they contribute the most overhead. The page_evictable() is a
function which does function prologue and epilogue, and that was used by
page reclaim path only. However, lru add is a very hot path, so it sounds
better to make it inline. However, it calls page_mapping() which is not
inlined either, but the disassemble shows it doesn't do push and pop
operations and it sounds not very straightforward to inline it.
Other than this, it sounds smp_mb() is not necessary for x86 since
SetPageLRU is atomic which enforces memory barrier already, replace it
with smp_mb__after_atomic() in the following patch.
With the two fixes applied, the tests can get back around 5% on that test
bench and get back normal on my VM. Since the test bench configuration is
not that usual and I also saw around 6% up on the latest upstream, so it
sounds good enough IMHO.
The below is test data (lru-file-readtwice throughput) against the v5.6-rc4:
mainline w/ inline fix
150MB 154MB
With this patch the throughput gets 2.67% up. The data with using
smp_mb__after_atomic() is showed in the following patch.
Shakeel Butt did the below test:
On a real machine with limiting the 'dd' on a single node and reading 100
GiB sparse file (less than a single node). Just ran a single instance to
not cause the lru lock contention. The cmdline used is "dd if=file-100GiB
of=/dev/null bs=4k". Ran the cmd 10 times with drop_caches in between and
measured the time it took.
Without patch: 56.64143 +- 0.672 sec
With patches: 56.10 +- 0.21 sec
[akpm@linux-foundation.org: move page_evictable() to internal.h]
Fixes: 9c4e6b1a70 ("mm, mlock, vmscan: no more skipping pagevecs")
Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Shakeel Butt <shakeelb@google.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Link: http://lkml.kernel.org/r/1584500541-46817-1-git-send-email-yang.shi@linux.alibaba.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit 68600f623d ("mm: don't miss the last page because of round-off
error") makes the scan size round up to @denominator regardless of the
memory cgroup's state, online or offline. This affects the overall
reclaiming behavior: the corresponding LRU list is eligible for
reclaiming only when its size logically right shifted by @sc->priority
is bigger than zero in the former formula.
For example, the inactive anonymous LRU list should have at least 0x4000
pages to be eligible for reclaiming when we have 60/12 for
swappiness/priority and without taking scan/rotation ratio into account.
After the roundup is applied, the inactive anonymous LRU list becomes
eligible for reclaiming when its size is bigger than or equal to 0x1000
in the same condition.
(0x4000 >> 12) * 60 / (60 + 140 + 1) = 1
((0x1000 >> 12) * 60) + 200) / (60 + 140 + 1) = 1
aarch64 has 512MB huge page size when the base page size is 64KB. The
memory cgroup that has a huge page is always eligible for reclaiming in
that case.
The reclaiming is likely to stop after the huge page is reclaimed,
meaing the further iteration on @sc->priority and the silbing and child
memory cgroups will be skipped. The overall behaviour has been changed.
This fixes the issue by applying the roundup to offlined memory cgroups
only, to give more preference to reclaim memory from offlined memory
cgroup. It sounds reasonable as those memory is unlikedly to be used by
anyone.
The issue was found by starting up 8 VMs on a Ampere Mustang machine,
which has 8 CPUs and 16 GB memory. Each VM is given with 2 vCPUs and
2GB memory. It took 264 seconds for all VMs to be completely up and
784MB swap is consumed after that. With this patch applied, it took 236
seconds and 60MB swap to do same thing. So there is 10% performance
improvement for my case. Note that KSM is disable while THP is enabled
in the testing.
total used free shared buff/cache available
Mem: 16196 10065 2049 16 4081 3749
Swap: 8175 784 7391
total used free shared buff/cache available
Mem: 16196 11324 3656 24 1215 2936
Swap: 8175 60 8115
Link: http://lkml.kernel.org/r/20200211024514.8730-1-gshan@redhat.com
Fixes: 68600f623d ("mm: don't miss the last page because of round-off error")
Signed-off-by: Gavin Shan <gshan@redhat.com>
Acked-by: Roman Gushchin <guro@fb.com>
Cc: <stable@vger.kernel.org> [4.20+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit 1b2ffb7896 ("[PATCH] Zone reclaim: Allow modification of zone
reclaim behavior")' defined RECLAIM_OFF/RECLAIM_ZONE, but never use
them, so better to remove them.
[dwagner@suse.de: fix sanity checks enabling]
Link: http://lkml.kernel.org/r/20200116131642.642-1-dwagner@suse.de
[akpm@linux-foundation.org: renumber the bits for neatness]
Link: http://lkml.kernel.org/r/1579005573-58923-1-git-send-email-alex.shi@linux.alibaba.com
Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com>
Signed-off-by: Daniel Wagner <dwagner@suse.de>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: "Tobin C. Harding" <tobin@kernel.org>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This macro was never used in git history. So better to remove.
Link: http://lkml.kernel.org/r/1579006500-127143-1-git-send-email-alex.shi@linux.alibaba.com
Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Qian Cai <cai@lca.pw>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The return value of shrink_node is not used, so remove unnecessary
operations.
Link: http://lkml.kernel.org/r/20191128143524.3223-1-fishland@aliyun.com
Signed-off-by: Liu Song <liu.song11@zte.com.cn>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Since commit 0a432dcbeb ("mm: shrinker: make shrinker not depend on
memcg kmem"), shrinkers' idr is protected by CONFIG_MEMCG instead of
CONFIG_MEMCG_KMEM, so it makes no sense to protect shrinker idr replace
with CONFIG_MEMCG_KMEM.
And in the CONFIG_MEMCG && CONFIG_SLOB case, shrinker_idr contains only
shrinker, and it is deferred_split_shrinker. But it is never actually
called, since idr_replace() is never compiled due to the wrong #ifdef.
The deferred_split_shrinker all the time is staying in half-registered
state, and it's never called for subordinate mem cgroups.
Link: http://lkml.kernel.org/r/1575486978-45249-1-git-send-email-yang.shi@linux.alibaba.com
Fixes: 0a432dcbeb ("mm: shrinker: make shrinker not depend on memcg kmem")
Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com>
Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: <stable@vger.kernel.org> [5.4+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We split the LRU lists into inactive and an active parts to maximize
workingset protection while allowing just enough inactive cache space to
faciltate readahead and writeback for one-off file accesses (e.g. a
linear scan through a file, or logging); or just enough inactive anon to
maintain recent reference information when reclaim needs to swap.
With cgroups and their nested LRU lists, we currently don't do this
correctly. While recursive cgroup reclaim establishes a relative LRU
order among the pages of all involved cgroups, inactive:active size
decisions are done on a per-cgroup level. As a result, we'll reclaim a
cgroup's workingset when it doesn't have cold pages, even when one of its
siblings has plenty of it that should be reclaimed first.
For example: workload A has 50M worth of hot cache but doesn't do any
one-off file accesses; meanwhile, parallel workload B scans files and
rarely accesses the same page twice.
If these workloads were to run in an uncgrouped system, A would be
protected from the high rate of cache faults from B. But if they were put
in parallel cgroups for memory accounting purposes, B's fast cache fault
rate would push out the hot cache pages of A. This is unexpected and
undesirable - the "scan resistance" of the page cache is broken.
This patch moves inactive:active size balancing decisions to the root of
reclaim - the same level where the LRU order is established.
It does this by looking at the recursive size of the inactive and the
active file sets of the cgroup subtree at the beginning of the reclaim
cycle, and then making a decision - scan or skip active pages - that
applies throughout the entire run and to every cgroup involved.
With that in place, in the test above, the VM will recognize that there
are plenty of inactive pages in the combined cache set of workloads A and
B and prefer the one-off cache in B over the hot pages in A. The scan
resistance of the cache is restored.
[cai@lca.pw: fix some -Wenum-conversion warnings]
Link: http://lkml.kernel.org/r/1573848697-29262-1-git-send-email-cai@lca.pw
Link: http://lkml.kernel.org/r/20191107205334.158354-4-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We use refault information to determine whether the cache workingset is
stable or transitioning, and dynamically adjust the inactive:active file
LRU ratio so as to maximize protection from one-off cache during stable
periods, and minimize IO during transitions.
With cgroups and their nested LRU lists, we currently don't do this
correctly. While recursive cgroup reclaim establishes a relative LRU
order among the pages of all involved cgroups, refaults only affect the
local LRU order in the cgroup in which they are occuring. As a result,
cache transitions can take longer in a cgrouped system as the active pages
of sibling cgroups aren't challenged when they should be.
[ Right now, this is somewhat theoretical, because the siblings, under
continued regular reclaim pressure, should eventually run out of
inactive pages - and since inactive:active *size* balancing is also
done on a cgroup-local level, we will challenge the active pages
eventually in most cases. But the next patch will move that relative
size enforcement to the reclaim root as well, and then this patch
here will be necessary to propagate refault pressure to siblings. ]
This patch moves refault detection to the root of reclaim. Instead of
remembering the cgroup owner of an evicted page, remember the cgroup that
caused the reclaim to happen. When refaults later occur, they'll
correctly influence the cross-cgroup LRU order that reclaim follows.
I.e. if global reclaim kicked out pages in some subgroup A/B/C, the
refault of those pages will challenge the global LRU order, and not just
the local order down inside C.
[hannes@cmpxchg.org: use page_memcg() instead of another lookup]
Link: http://lkml.kernel.org/r/20191115160722.GA309754@cmpxchg.org
Link: http://lkml.kernel.org/r/20191107205334.158354-3-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Shakeel Butt <shakeelb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "mm: fix page aging across multiple cgroups".
When applications are put into unconfigured cgroups for memory accounting
purposes, the cgrouping itself should not change the behavior of the page
reclaim code. We expect the VM to reclaim the coldest pages in the
system. But right now the VM can reclaim hot pages in one cgroup while
there is eligible cold cache in others.
This is because one part of the reclaim algorithm isn't truly cgroup
hierarchy aware: the inactive/active list balancing. That is the part
that is supposed to protect hot cache data from one-off streaming IO.
The recursive cgroup reclaim scheme will scan and rotate the physical LRU
lists of each eligible cgroup at the same rate in a round-robin fashion,
thereby establishing a relative order among the pages of all those
cgroups. However, the inactive/active balancing decisions are made
locally within each cgroup, so when a cgroup is running low on cold pages,
its hot pages will get reclaimed - even when sibling cgroups have plenty
of cold cache eligible in the same reclaim run.
For example:
[root@ham ~]# head -n1 /proc/meminfo
MemTotal: 1016336 kB
[root@ham ~]# ./reclaimtest2.sh
Establishing 50M active files in cgroup A...
Hot pages cached: 12800/12800 workingset-a
Linearly scanning through 18G of file data in cgroup B:
real 0m4.269s
user 0m0.051s
sys 0m4.182s
Hot pages cached: 134/12800 workingset-a
The streaming IO in B, which doesn't benefit from caching at all, pushes
out most of the workingset in A.
Solution
This series fixes the problem by elevating inactive/active balancing
decisions to the toplevel of the reclaim run. This is either a cgroup
that hit its limit, or straight-up global reclaim if there is physical
memory pressure. From there, it takes a recursive view of the cgroup
subtree to decide whether page deactivation is necessary.
In the test above, the VM will then recognize that cgroup B has plenty of
eligible cold cache, and that the hot pages in A can be spared:
[root@ham ~]# ./reclaimtest2.sh
Establishing 50M active files in cgroup A...
Hot pages cached: 12800/12800 workingset-a
Linearly scanning through 18G of file data in cgroup B:
real 0m4.244s
user 0m0.064s
sys 0m4.177s
Hot pages cached: 12800/12800 workingset-a
Implementation
Whether active pages can be deactivated or not is influenced by two
factors: the inactive list dropping below a minimum size relative to the
active list, and the occurence of refaults.
This patch series first moves refault detection to the reclaim root, then
enforces the minimum inactive size based on a recursive view of the cgroup
tree's LRUs.
History
Note that this actually never worked correctly in Linux cgroups. In the
past it worked for global reclaim and leaf limit reclaim only (we used to
have two physical LRU linkages per page), but it never worked for
intermediate limit reclaim over multiple leaf cgroups.
We're noticing this now because 1) we're putting everything into cgroups
for accounting, not just the things we want to control and 2) we're moving
away from leaf limits that invoke reclaim on individual cgroups, toward
large tree reclaim, triggered by high-level limits, or physical memory
pressure that is influenced by local protections such as memory.low and
memory.min instead.
This patch (of 3):
When file pages are lower than the watermark on a node, we try to force
scan anonymous pages to counter-act the balancing algorithms preference
for new file pages when they are likely thrashing. This is a node-level
decision, but it's currently made each time we look at an lruvec. This is
unnecessarily expensive and also a layering violation that makes the code
harder to understand.
Clean this up by making the check once per node and setting a flag in the
scan_control.
Link: http://lkml.kernel.org/r/20191107205334.158354-2-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Rik van Riel <riel@surriel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The current writeback congestion tracking has separate flags for kswapd
reclaim (node level) and cgroup limit reclaim (memcg-node level). This is
unnecessarily complicated: the lruvec is an existing abstraction layer for
that node-memcg intersection.
Introduce lruvec->flags and LRUVEC_CONGESTED. Then track that at the
reclaim root level, which is either the NUMA node for global reclaim, or
the cgroup-node intersection for cgroup reclaim.
Link: http://lkml.kernel.org/r/20191022144803.302233-9-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Roman Gushchin <guro@fb.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This function is getting long and unwieldy, split out the memcg bits.
The updated shrink_node() handles the generic (node) reclaim aspects:
- global vmpressure notifications
- writeback and congestion throttling
- reclaim/compaction management
- kswapd giving up on unreclaimable nodes
It then calls a new shrink_node_memcgs() which handles cgroup specifics:
- the cgroup tree traversal
- memory.low considerations
- per-cgroup slab shrinking callbacks
- per-cgroup vmpressure notifications
[hannes@cmpxchg.org: rename "root" to "target_memcg", per Roman]
Link: http://lkml.kernel.org/r/20191025143640.GA386981@cmpxchg.org
Link: http://lkml.kernel.org/r/20191022144803.302233-8-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Roman Gushchin <guro@fb.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
An lruvec holds LRU pages owned by a certain NUMA node and cgroup.
Instead of awkwardly passing around a combination of a pgdat and a memcg
pointer, pass down the lruvec as soon as we can look it up.
Nested callers that need to access node or cgroup properties can look them
them up if necessary, but there are only a few cases.
Link: http://lkml.kernel.org/r/20191022144803.302233-7-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Roman Gushchin <guro@fb.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Most of the function body is inside a loop, which imposes an additional
indentation and scoping level that makes the code a bit hard to follow and
modify.
The looping only happens in case of reclaim-compaction, which isn't the
common case. So rather than adding yet another function level to the
reclaim path and have every reclaim invocation go through a level that
only exists for one specific cornercase, use a retry goto.
Link: http://lkml.kernel.org/r/20191022144803.302233-6-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Roman Gushchin <guro@fb.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Seven years after introducing the global_reclaim() function, I still have
to double take when reading a callsite. I don't know how others do it,
this is a terrible name.
Invert the meaning and rename it to cgroup_reclaim().
[ After all, "global reclaim" is just regular reclaim invoked from the
page allocator. It's reclaim on behalf of a cgroup limit that is a
special case of reclaim, and should be explicit - not the reverse. ]
sane_reclaim() isn't very descriptive either: it tests whether we can use
the regular writeback throttling - available during regular page reclaim
or cgroup2 limit reclaim - or need to use the broken
wait_on_page_writeback() method. Use "writeback_throttling_sane()".
Link: http://lkml.kernel.org/r/20191022144803.302233-5-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Roman Gushchin <guro@fb.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
inactive_list_is_low() should be about one thing: checking the ratio
between inactive and active list. Kitchensink checks like the one for
swap space makes the function hard to use and modify its callsites.
Luckly, most callers already have an understanding of the swap situation,
so it's easy to clean up.
get_scan_count() has its own, memcg-aware swap check, and doesn't even get
to the inactive_list_is_low() check on the anon list when there is no swap
space available.
shrink_list() is called on the results of get_scan_count(), so that check
is redundant too.
age_active_anon() has its own totalswap_pages check right before it checks
the list proportions.
The shrink_node_memcg() site is the only one that doesn't do its own swap
check. Add it there.
Then delete the swap check from inactive_list_is_low().
Link: http://lkml.kernel.org/r/20191022144803.302233-4-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Roman Gushchin <guro@fb.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There is a per-memcg lruvec and a NUMA node lruvec. Which one is being
used is somewhat confusing right now, and it's easy to make mistakes -
especially when it comes to global reclaim.
How it works: when memory cgroups are enabled, we always use the
root_mem_cgroup's per-node lruvecs. When memory cgroups are not compiled
in or disabled at runtime, we use pgdat->lruvec.
Document that in a comment.
Due to the way the reclaim code is generalized, all lookups use the
mem_cgroup_lruvec() helper function, and nobody should have to find the
right lruvec manually right now. But to avoid future mistakes, rename the
pgdat->lruvec member to pgdat->__lruvec and delete the convenience wrapper
that suggests it's a commonly accessed member.
While in this area, swap the mem_cgroup_lruvec() argument order. The name
suggests a memcg operation, yet it takes a pgdat first and a memcg second.
I have to double take every time I call this. Fix that.
Link: http://lkml.kernel.org/r/20191022144803.302233-3-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Cc: Roman Gushchin <guro@fb.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "mm: vmscan: cgroup-related cleanups".
Here are 8 patches that clean up the reclaim code's interaction with
cgroups a bit. They're not supposed to change any behavior, just make
the implementation easier to understand and work with.
This patch (of 8):
This function currently takes the node or lruvec size and subtracts the
zones that are excluded by the classzone index of the allocation. It uses
four different types of counters to do this.
Just add up the eligible zones.
[cai@lca.pw: fix an undefined behavior for zone id]
Link: http://lkml.kernel.org/r/20191108204407.1435-1-cai@lca.pw
[akpm@linux-foundation.org: deal with the MAX_NR_ZONES special case. per Qian Cai]
Link: http://lkml.kernel.org/r/64E60F6F-7582-427B-8DD5-EF97B1656F5A@lca.pw
Link: http://lkml.kernel.org/r/20191022144803.302233-2-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Roman Gushchin <guro@fb.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Since lumpy reclaim was removed in v3.5 scan_control is not used by
may_write_to_{queue|inode} and pageout() anymore, remove the unused
parameter.
Link: http://lkml.kernel.org/r/1570124498-19300-1-git-send-email-yang.shi@linux.alibaba.com
Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Since 9092c71bb7 ("mm: use sc->priority for slab shrink targets") the
argument 'unsigned long *lru_pages' passed around with no purpose. Remove
it.
Link: http://lkml.kernel.org/r/20190228083329.31892-4-aryabinin@virtuozzo.com
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: William Kucharski <william.kucharski@oracle.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Since commit 1ba6fc9af3 ("mm: vmscan: do not share cgroup iteration
between reclaimers"), the memcg reclaim does not bail out earlier based
on sc->nr_reclaimed and will traverse all the nodes. All the
reclaimable pages of the memcg on all the nodes will be scanned relative
to the reclaim priority. So, there is no need to maintain state
regarding which node to start the memcg reclaim from.
This patch effectively reverts the commit 889976dbcb ("memcg: reclaim
memory from nodes in round-robin order") and commit 453a9bf347
("memcg: fix numa scan information update to be triggered by memory
event").
[shakeelb@google.com: v2]
Link: http://lkml.kernel.org/r/20191030204232.139424-1-shakeelb@google.com
Link: http://lkml.kernel.org/r/20191029234753.224143-1-shakeelb@google.com
Signed-off-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Roman Gushchin <guro@fb.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Greg Thelen <gthelen@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
__remove_mapping() assumes that pages can only be either base pages or
HPAGE_PMD_SIZE. Ask the page what size it is.
Link: http://lkml.kernel.org/r/20191017164223.2762148-4-songliubraving@fb.com
Fixes: 99cb0dbd47 ("mm,thp: add read-only THP support for (non-shmem) FS")
Signed-off-by: William Kucharski <william.kucharski@oracle.com>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Song Liu <songliubraving@fb.com>
Acked-by: Yang Shi <yang.shi@linux.alibaba.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit 1a61ab8038 ("mm: memcontrol: replace zone summing with
lruvec_page_state()") has made lruvec_page_state to use per-cpu counters
instead of calculating it directly from lru_zone_size with an idea that
this would be more effective.
Tim has reported that this is not really the case for their database
benchmark which is showing an opposite results where lruvec_page_state
is taking up a huge chunk of CPU cycles (about 25% of the system time
which is roughly 7% of total cpu cycles) on 5.3 kernels. The workload
is running on a larger machine (96cpus), it has many cgroups (500) and
it is heavily direct reclaim bound.
Tim Chen said:
: The problem can also be reproduced by running simple multi-threaded
: pmbench benchmark with a fast Optane SSD swap (see profile below).
:
:
: 6.15% 3.08% pmbench [kernel.vmlinux] [k] lruvec_lru_size
: |
: |--3.07%--lruvec_lru_size
: | |
: | |--2.11%--cpumask_next
: | | |
: | | --1.66%--find_next_bit
: | |
: | --0.57%--call_function_interrupt
: | |
: | --0.55%--smp_call_function_interrupt
: |
: |--1.59%--0x441f0fc3d009
: | _ops_rdtsc_init_base_freq
: | access_histogram
: | page_fault
: | __do_page_fault
: | handle_mm_fault
: | __handle_mm_fault
: | |
: | --1.54%--do_swap_page
: | swapin_readahead
: | swap_cluster_readahead
: | |
: | --1.53%--read_swap_cache_async
: | __read_swap_cache_async
: | alloc_pages_vma
: | __alloc_pages_nodemask
: | __alloc_pages_slowpath
: | try_to_free_pages
: | do_try_to_free_pages
: | shrink_node
: | shrink_node_memcg
: | |
: | |--0.77%--lruvec_lru_size
: | |
: | --0.76%--inactive_list_is_low
: | |
: | --0.76%--lruvec_lru_size
: |
: --1.50%--measure_read
: page_fault
: __do_page_fault
: handle_mm_fault
: __handle_mm_fault
: do_swap_page
: swapin_readahead
: swap_cluster_readahead
: |
: --1.48%--read_swap_cache_async
: __read_swap_cache_async
: alloc_pages_vma
: __alloc_pages_nodemask
: __alloc_pages_slowpath
: try_to_free_pages
: do_try_to_free_pages
: shrink_node
: shrink_node_memcg
: |
: |--0.75%--inactive_list_is_low
: | |
: | --0.75%--lruvec_lru_size
: |
: --0.73%--lruvec_lru_size
The likely culprit is the cache traffic the lruvec_page_state_local
generates. Dave Hansen says:
: I was thinking purely of the cache footprint. If it's reading
: pn->lruvec_stat_local->count[idx] is three separate cachelines, so 192
: bytes of cache *96 CPUs = 18k of data, mostly read-only. 1 cgroup would
: be 18k of data for the whole system and the caching would be pretty
: efficient and all 18k would probably survive a tight page fault loop in
: the L1. 500 cgroups would be ~90k of data per CPU thread which doesn't
: fit in the L1 and probably wouldn't survive a tight page fault loop if
: both logical threads were banging on different cgroups.
:
: It's just a theory, but it's why I noted the number of cgroups when I
: initially saw this show up in profiles
Fix the regression by partially reverting the said commit and calculate
the lru size explicitly.
Link: http://lkml.kernel.org/r/20190905071034.16822-1-honglei.wang@oracle.com
Fixes: 1a61ab8038 ("mm: memcontrol: replace zone summing with lruvec_page_state()")
Signed-off-by: Honglei Wang <honglei.wang@oracle.com>
Reported-by: Tim Chen <tim.c.chen@linux.intel.com>
Acked-by: Tim Chen <tim.c.chen@linux.intel.com>
Tested-by: Tim Chen <tim.c.chen@linux.intel.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Roman Gushchin <guro@fb.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: <stable@vger.kernel.org> [5.2+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch is an incremental improvement on the existing
memory.{low,min} relative reclaim work to base its scan pressure
calculations on how much protection is available compared to the current
usage, rather than how much the current usage is over some protection
threshold.
This change doesn't change the experience for the user in the normal
case too much. One benefit is that it replaces the (somewhat arbitrary)
100% cutoff with an indefinite slope, which makes it easier to ballpark
a memory.low value.
As well as this, the old methodology doesn't quite apply generically to
machines with varying amounts of physical memory. Let's say we have a
top level cgroup, workload.slice, and another top level cgroup,
system-management.slice. We want to roughly give 12G to
system-management.slice, so on a 32GB machine we set memory.low to 20GB
in workload.slice, and on a 64GB machine we set memory.low to 52GB.
However, because these are relative amounts to the total machine size,
while the amount of memory we want to generally be willing to yield to
system.slice is absolute (12G), we end up putting more pressure on
system.slice just because we have a larger machine and a larger workload
to fill it, which seems fairly unintuitive. With this new behaviour, we
don't end up with this unintended side effect.
Previously the way that memory.low protection works is that if you are
50% over a certain baseline, you get 50% of your normal scan pressure.
This is certainly better than the previous cliff-edge behaviour, but it
can be improved even further by always considering memory under the
currently enforced protection threshold to be out of bounds. This means
that we can set relatively low memory.low thresholds for variable or
bursty workloads while still getting a reasonable level of protection,
whereas with the previous version we may still trivially hit the 100%
clamp. The previous 100% clamp is also somewhat arbitrary, whereas this
one is more concretely based on the currently enforced protection
threshold, which is likely easier to reason about.
There is also a subtle issue with the way that proportional reclaim
worked previously -- it promotes having no memory.low, since it makes
pressure higher during low reclaim. This happens because we base our
scan pressure modulation on how far memory.current is between memory.min
and memory.low, but if memory.low is unset, we only use the overage
method. In most cromulent configurations, this then means that we end
up with *more* pressure than with no memory.low at all when we're in low
reclaim, which is not really very usable or expected.
With this patch, memory.low and memory.min affect reclaim pressure in a
more understandable and composable way. For example, from a user
standpoint, "protected" memory now remains untouchable from a reclaim
aggression standpoint, and users can also have more confidence that
bursty workloads will still receive some amount of guaranteed
protection.
Link: http://lkml.kernel.org/r/20190322160307.GA3316@chrisdown.name
Signed-off-by: Chris Down <chris@chrisdown.name>
Reviewed-by: Roman Gushchin <guro@fb.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Roman points out that when when we do the low reclaim pass, we scale the
reclaim pressure relative to position between 0 and the maximum
protection threshold.
However, if the maximum protection is based on memory.elow, and
memory.emin is above zero, this means we still may get binary behaviour
on second-pass low reclaim. This is because we scale starting at 0, not
starting at memory.emin, and since we don't scan at all below emin, we
end up with cliff behaviour.
This should be a fairly uncommon case since usually we don't go into the
second pass, but it makes sense to scale our low reclaim pressure
starting at emin.
You can test this by catting two large sparse files, one in a cgroup
with emin set to some moderate size compared to physical RAM, and
another cgroup without any emin. In both cgroups, set an elow larger
than 50% of physical RAM. The one with emin will have less page
scanning, as reclaim pressure is lower.
Rebase on top of and apply the same idea as what was applied to handle
cgroup_memory=disable properly for the original proportional patch
http://lkml.kernel.org/r/20190201045711.GA18302@chrisdown.name ("mm,
memcg: Handle cgroup_disable=memory when getting memcg protection").
Link: http://lkml.kernel.org/r/20190201051810.GA18895@chrisdown.name
Signed-off-by: Chris Down <chris@chrisdown.name>
Suggested-by: Roman Gushchin <guro@fb.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Dennis Zhou <dennis@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
cgroup v2 introduces two memory protection thresholds: memory.low
(best-effort) and memory.min (hard protection). While they generally do
what they say on the tin, there is a limitation in their implementation
that makes them difficult to use effectively: that cliff behaviour often
manifests when they become eligible for reclaim. This patch implements
more intuitive and usable behaviour, where we gradually mount more
reclaim pressure as cgroups further and further exceed their protection
thresholds.
This cliff edge behaviour happens because we only choose whether or not
to reclaim based on whether the memcg is within its protection limits
(see the use of mem_cgroup_protected in shrink_node), but we don't vary
our reclaim behaviour based on this information. Imagine the following
timeline, with the numbers the lruvec size in this zone:
1. memory.low=1000000, memory.current=999999. 0 pages may be scanned.
2. memory.low=1000000, memory.current=1000000. 0 pages may be scanned.
3. memory.low=1000000, memory.current=1000001. 1000001* pages may be
scanned. (?!)
* Of course, we won't usually scan all available pages in the zone even
without this patch because of scan control priority, over-reclaim
protection, etc. However, as shown by the tests at the end, these
techniques don't sufficiently throttle such an extreme change in input,
so cliff-like behaviour isn't really averted by their existence alone.
Here's an example of how this plays out in practice. At Facebook, we are
trying to protect various workloads from "system" software, like
configuration management tools, metric collectors, etc (see this[0] case
study). In order to find a suitable memory.low value, we start by
determining the expected memory range within which the workload will be
comfortable operating. This isn't an exact science -- memory usage deemed
"comfortable" will vary over time due to user behaviour, differences in
composition of work, etc, etc. As such we need to ballpark memory.low,
but doing this is currently problematic:
1. If we end up setting it too low for the workload, it won't have
*any* effect (see discussion above). The group will receive the full
weight of reclaim and won't have any priority while competing with the
less important system software, as if we had no memory.low configured
at all.
2. Because of this behaviour, we end up erring on the side of setting
it too high, such that the comfort range is reliably covered. However,
protected memory is completely unavailable to the rest of the system,
so we might cause undue memory and IO pressure there when we *know* we
have some elasticity in the workload.
3. Even if we get the value totally right, smack in the middle of the
comfort zone, we get extreme jumps between no pressure and full
pressure that cause unpredictable pressure spikes in the workload due
to the current binary reclaim behaviour.
With this patch, we can set it to our ballpark estimation without too much
worry. Any undesirable behaviour, such as too much or too little reclaim
pressure on the workload or system will be proportional to how far our
estimation is off. This means we can set memory.low much more
conservatively and thus waste less resources *without* the risk of the
workload falling off a cliff if we overshoot.
As a more abstract technical description, this unintuitive behaviour
results in having to give high-priority workloads a large protection
buffer on top of their expected usage to function reliably, as otherwise
we have abrupt periods of dramatically increased memory pressure which
hamper performance. Having to set these thresholds so high wastes
resources and generally works against the principle of work conservation.
In addition, having proportional memory reclaim behaviour has other
benefits. Most notably, before this patch it's basically mandatory to set
memory.low to a higher than desirable value because otherwise as soon as
you exceed memory.low, all protection is lost, and all pages are eligible
to scan again. By contrast, having a gradual ramp in reclaim pressure
means that you now still get some protection when thresholds are exceeded,
which means that one can now be more comfortable setting memory.low to
lower values without worrying that all protection will be lost. This is
important because workingset size is really hard to know exactly,
especially with variable workloads, so at least getting *some* protection
if your workingset size grows larger than you expect increases user
confidence in setting memory.low without a huge buffer on top being
needed.
Thanks a lot to Johannes Weiner and Tejun Heo for their advice and
assistance in thinking about how to make this work better.
In testing these changes, I intended to verify that:
1. Changes in page scanning become gradual and proportional instead of
binary.
To test this, I experimented stepping further and further down
memory.low protection on a workload that floats around 19G workingset
when under memory.low protection, watching page scan rates for the
workload cgroup:
+------------+-----------------+--------------------+--------------+
| memory.low | test (pgscan/s) | control (pgscan/s) | % of control |
+------------+-----------------+--------------------+--------------+
| 21G | 0 | 0 | N/A |
| 17G | 867 | 3799 | 23% |
| 12G | 1203 | 3543 | 34% |
| 8G | 2534 | 3979 | 64% |
| 4G | 3980 | 4147 | 96% |
| 0 | 3799 | 3980 | 95% |
+------------+-----------------+--------------------+--------------+
As you can see, the test kernel (with a kernel containing this
patch) ramps up page scanning significantly more gradually than the
control kernel (without this patch).
2. More gradual ramp up in reclaim aggression doesn't result in
premature OOMs.
To test this, I wrote a script that slowly increments the number of
pages held by stress(1)'s --vm-keep mode until a production system
entered severe overall memory contention. This script runs in a highly
protected slice taking up the majority of available system memory.
Watching vmstat revealed that page scanning continued essentially
nominally between test and control, without causing forward reclaim
progress to become arrested.
[0]: https://facebookmicrosites.github.io/cgroup2/docs/overview.html#case-study-the-fbtax2-project
[akpm@linux-foundation.org: reflow block comments to fit in 80 cols]
[chris@chrisdown.name: handle cgroup_disable=memory when getting memcg protection]
Link: http://lkml.kernel.org/r/20190201045711.GA18302@chrisdown.name
Link: http://lkml.kernel.org/r/20190124014455.GA6396@chrisdown.name
Signed-off-by: Chris Down <chris@chrisdown.name>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Roman Gushchin <guro@fb.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When a process expects no accesses to a certain memory range for a long
time, it could hint kernel that the pages can be reclaimed instantly but
data should be preserved for future use. This could reduce workingset
eviction so it ends up increasing performance.
This patch introduces the new MADV_PAGEOUT hint to madvise(2) syscall.
MADV_PAGEOUT can be used by a process to mark a memory range as not
expected to be used for a long time so that kernel reclaims *any LRU*
pages instantly. The hint can help kernel in deciding which pages to
evict proactively.
A note: It doesn't apply SWAP_CLUSTER_MAX LRU page isolation limit
intentionally because it's automatically bounded by PMD size. If PMD
size(e.g., 256) makes some trouble, we could fix it later by limit it to
SWAP_CLUSTER_MAX[1].
- man-page material
MADV_PAGEOUT (since Linux x.x)
Do not expect access in the near future so pages in the specified
regions could be reclaimed instantly regardless of memory pressure.
Thus, access in the range after successful operation could cause
major page fault but never lose the up-to-date contents unlike
MADV_DONTNEED. Pages belonging to a shared mapping are only processed
if a write access is allowed for the calling process.
MADV_PAGEOUT cannot be applied to locked pages, Huge TLB pages, or
VM_PFNMAP pages.
[1] https://lore.kernel.org/lkml/20190710194719.GS29695@dhcp22.suse.cz/
[minchan@kernel.org: clear PG_active on MADV_PAGEOUT]
Link: http://lkml.kernel.org/r/20190802200643.GA181880@google.com
[akpm@linux-foundation.org: resolve conflicts with hmm.git]
Link: http://lkml.kernel.org/r/20190726023435.214162-5-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Reported-by: kbuild test robot <lkp@intel.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: James E.J. Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Chris Zankel <chris@zankel.net>
Cc: Daniel Colascione <dancol@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Joel Fernandes (Google) <joel@joelfernandes.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Oleksandr Natalenko <oleksandr@redhat.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Sonny Rao <sonnyrao@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Tim Murray <timmurray@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The local variable references in shrink_page_list is PAGEREF_RECLAIM_CLEAN
as default. It is for preventing to reclaim dirty pages when CMA try to
migrate pages. Strictly speaking, we don't need it because CMA didn't
allow to write out by .may_writepage = 0 in reclaim_clean_pages_from_list.
Moreover, it has a problem to prevent anonymous pages's swap out even
though force_reclaim = true in shrink_page_list on upcoming patch. So
this patch makes references's default value to PAGEREF_RECLAIM and rename
force_reclaim with ignore_references to make it more clear.
This is a preparatory work for next patch.
Link: http://lkml.kernel.org/r/20190726023435.214162-3-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Chris Zankel <chris@zankel.net>
Cc: Daniel Colascione <dancol@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Hillf Danton <hdanton@sina.com>
Cc: James E.J. Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Joel Fernandes (Google) <joel@joelfernandes.org>
Cc: kbuild test robot <lkp@intel.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Oleksandr Natalenko <oleksandr@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Sonny Rao <sonnyrao@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Tim Murray <timmurray@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently shrinker is just allocated and can work when memcg kmem is
enabled. But, THP deferred split shrinker is not slab shrinker, it
doesn't make too much sense to have such shrinker depend on memcg kmem.
It should be able to reclaim THP even though memcg kmem is disabled.
Introduce a new shrinker flag, SHRINKER_NONSLAB, for non-slab shrinker.
When memcg kmem is disabled, just such shrinkers can be called in
shrinking memcg slab.
[yang.shi@linux.alibaba.com: add comment]
Link: http://lkml.kernel.org/r/1566496227-84952-4-git-send-email-yang.shi@linux.alibaba.com
Link: http://lkml.kernel.org/r/1565144277-36240-4-git-send-email-yang.shi@linux.alibaba.com
Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Qian Cai <cai@lca.pw>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
A later patch makes THP deferred split shrinker memcg aware, but it needs
page->mem_cgroup information in THP destructor, which is called after
mem_cgroup_uncharge() now.
So move mem_cgroup_uncharge() from __page_cache_release() to compound page
destructor, which is called by both THP and other compound pages except
HugeTLB. And call it in __put_single_page() for single order page.
Link: http://lkml.kernel.org/r/1565144277-36240-3-git-send-email-yang.shi@linux.alibaba.com
Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com>
Suggested-by: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Qian Cai <cai@lca.pw>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
After commit "mm, reclaim: make should_continue_reclaim perform dryrun
detection", closer look at the function shows, that nr_reclaimed == 0
means the function will always return false. And since non-zero
nr_reclaimed implies non_zero nr_scanned, testing nr_scanned serves no
purpose, and so does the testing for __GFP_RETRY_MAYFAIL.
This patch thus cleans up the function to test only !nr_reclaimed upfront,
and remove the __GFP_RETRY_MAYFAIL test and nr_scanned parameter
completely. Comment is also updated, explaining that approximating "full
LRU list has been scanned" with nr_scanned == 0 didn't really work.
Link: http://lkml.kernel.org/r/20190806014744.15446-3-mike.kravetz@oracle.com
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Acked-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "address hugetlb page allocation stalls", v2.
Allocation of hugetlb pages via sysctl or procfs can stall for minutes or
hours. A simple example on a two node system with 8GB of memory is as
follows:
echo 4096 > /sys/devices/system/node/node1/hugepages/hugepages-2048kB/nr_hugepages
echo 4096 > /proc/sys/vm/nr_hugepages
Obviously, both allocation attempts will fall short of their 8GB goal.
However, one or both of these commands may stall and not be interruptible.
The issues were initially discussed in mail thread [1] and RFC code at
[2].
This series addresses the issues causing the stalls. There are two
distinct fixes, a cleanup, and an optimization. The reclaim patch by
Hillf and compaction patch by Vlasitmil address corner cases in their
respective areas. hugetlb page allocation could stall due to either of
these issues. Vlasitmil added a cleanup patch after Hillf's
modifications. The hugetlb patch by Mike is an optimization suggested
during the debug and development process.
[1] http://lkml.kernel.org/r/d38a095e-dc39-7e82-bb76-2c9247929f07@oracle.com
[2] http://lkml.kernel.org/r/20190724175014.9935-1-mike.kravetz@oracle.com
This patch (of 4):
Address the issue of should_continue_reclaim returning true too often for
__GFP_RETRY_MAYFAIL attempts when !nr_reclaimed and nr_scanned. This was
observed during hugetlb page allocation causing stalls for minutes or
hours.
We can stop reclaiming pages if compaction reports it can make a progress.
There might be side-effects for other high-order allocations that would
potentially benefit from reclaiming more before compaction so that they
would be faster and less likely to stall. However, the consequences of
premature/over-reclaim are considered worse.
We can also bail out of reclaiming pages if we know that there are not
enough inactive lru pages left to satisfy the costly allocation.
We can give up reclaiming pages too if we see dryrun occur, with the
certainty of plenty of inactive pages. IOW with dryrun detected, we are
sure we have reclaimed as many pages as we could.
Link: http://lkml.kernel.org/r/20190806014744.15446-2-mike.kravetz@oracle.com
Signed-off-by: Hillf Danton <hdanton@sina.com>
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Tested-by: Mike Kravetz <mike.kravetz@oracle.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
One of our services observed a high rate of cgroup OOM kills in the
presence of large amounts of clean cache. Debugging showed that the
culprit is the shared cgroup iteration in page reclaim.
Under high allocation concurrency, multiple threads enter reclaim at the
same time. Fearing overreclaim when we first switched from the single
global LRU to cgrouped LRU lists, we introduced a shared iteration state
for reclaim invocations - whether 1 or 20 reclaimers are active
concurrently, we only walk the cgroup tree once: the 1st reclaimer
reclaims the first cgroup, the second the second one etc. With more
reclaimers than cgroups, we start another walk from the top.
This sounded reasonable at the time, but the problem is that reclaim
concurrency doesn't scale with allocation concurrency. As reclaim
concurrency increases, the amount of memory individual reclaimers get to
scan gets smaller and smaller. Individual reclaimers may only see one
cgroup per cycle, and that may not have much reclaimable memory. We see
individual reclaimers declare OOM when there is plenty of reclaimable
memory available in cgroups they didn't visit.
This patch does away with the shared iterator, and every reclaimer is
allowed to scan the full cgroup tree and see all of reclaimable memory,
just like it would on a non-cgrouped system. This way, when OOM is
declared, we know that the reclaimer actually had a chance.
To still maintain fairness in reclaim pressure, disallow cgroup reclaim
from bailing out of the tree walk early. Kswapd and regular direct
reclaim already don't bail, so it's not clear why limit reclaim would have
to, especially since it only walks subtrees to begin with.
This change completely eliminates the OOM kills on our service, while
showing no signs of overreclaim - no increased scan rates, %sys time, or
abrupt free memory spikes. I tested across 100 machines that have 64G of
RAM and host about 300 cgroups each.
[ It's possible overreclaim never was a *practical* issue to begin
with - it was simply a concern we had on the mailing lists at the
time, with no real data to back it up. But we have also added more
bail-out conditions deeper inside reclaim (e.g. the proportional
exit in shrink_node_memcg) since. Regardless, now we have data that
suggests full walks are more reliable and scale just fine. ]
Link: http://lkml.kernel.org/r/20190812192316.13615-1-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Roman Gushchin <guro@fb.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Replace 1 << compound_order(page) with compound_nr(page). Minor
improvements in readability.
Link: http://lkml.kernel.org/r/20190721104612.19120-4-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Adric Blake has noticed[1] the following warning:
WARNING: CPU: 7 PID: 175 at mm/vmscan.c:245 set_task_reclaim_state+0x1e/0x40
[...]
Call Trace:
mem_cgroup_shrink_node+0x9b/0x1d0
mem_cgroup_soft_limit_reclaim+0x10c/0x3a0
balance_pgdat+0x276/0x540
kswapd+0x200/0x3f0
? wait_woken+0x80/0x80
kthread+0xfd/0x130
? balance_pgdat+0x540/0x540
? kthread_park+0x80/0x80
ret_from_fork+0x35/0x40
---[ end trace 727343df67b2398a ]---
which tells us that soft limit reclaim is about to overwrite the
reclaim_state configured up in the call chain (kswapd in this case but
the direct reclaim is equally possible). This means that reclaim stats
would get misleading once the soft reclaim returns and another reclaim
is done.
Fix the warning by dropping set_task_reclaim_state from the soft reclaim
which is always called with reclaim_state set up.
[1] http://lkml.kernel.org/r/CAE1jjeePxYPvw1mw2B3v803xHVR_BNnz0hQUY_JDMN8ny29M6w@mail.gmail.com
Link: http://lkml.kernel.org/r/20190828071808.20410-1-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reported-by: Adric Blake <promarbler14@gmail.com>
Acked-by: Yafang Shao <laoar.shao@gmail.com>
Acked-by: Yang Shi <yang.shi@linux.alibaba.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Hillf Danton <hdanton@sina.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Dave Chinner reported a problem pointing a finger at commit 1c30844d2d
("mm: reclaim small amounts of memory when an external fragmentation
event occurs").
The report is extensive:
https://lore.kernel.org/linux-mm/20190807091858.2857-1-david@fromorbit.com/
and it's worth recording the most relevant parts (colorful language and
typos included).
When running a simple, steady state 4kB file creation test to
simulate extracting tarballs larger than memory full of small
files into the filesystem, I noticed that once memory fills up
the cache balance goes to hell.
The workload is creating one dirty cached inode for every dirty
page, both of which should require a single IO each to clean and
reclaim, and creation of inodes is throttled by the rate at which
dirty writeback runs at (via balance dirty pages). Hence the ingest
rate of new cached inodes and page cache pages is identical and
steady. As a result, memory reclaim should quickly find a steady
balance between page cache and inode caches.
The moment memory fills, the page cache is reclaimed at a much
faster rate than the inode cache, and evidence suggests that
the inode cache shrinker is not being called when large batches
of pages are being reclaimed. In roughly the same time period
that it takes to fill memory with 50% pages and 50% slab caches,
memory reclaim reduces the page cache down to just dirty pages
and slab caches fill the entirety of memory.
The LRU is largely full of dirty pages, and we're getting spikes
of random writeback from memory reclaim so it's all going to shit.
Behaviour never recovers, the page cache remains pinned at just
dirty pages, and nothing I could tune would make any difference.
vfs_cache_pressure makes no difference - I would set it so high
it should trim the entire inode caches in a single pass, yet it
didn't do anything. It was clear from tracing and live telemetry
that the shrinkers were pretty much not running except when
there was absolutely no memory free at all, and then they did
the minimum necessary to free memory to make progress.
So I went looking at the code, trying to find places where pages
got reclaimed and the shrinkers weren't called. There's only one
- kswapd doing boosted reclaim as per commit 1c30844d2d ("mm:
reclaim small amounts of memory when an external fragmentation
event occurs").
The watermark boosting introduced by the commit is triggered in response
to an allocation "fragmentation event". The boosting was not intended
to target THP specifically and triggers even if THP is disabled.
However, with Dave's perfectly reasonable workload, fragmentation events
can be very common given the ratio of slab to page cache allocations so
boosting remains active for long periods of time.
As high-order allocations might use compaction and compaction cannot
move slab pages the decision was made in the commit to special-case
kswapd when watermarks are boosted -- kswapd avoids reclaiming slab as
reclaiming slab does not directly help compaction.
As Dave notes, this decision means that slab can be artificially
protected for long periods of time and messes up the balance with slab
and page caches.
Removing the special casing can still indirectly help avoid
fragmentation by avoiding fragmentation-causing events due to slab
allocation as pages from a slab pageblock will have some slab objects
freed. Furthermore, with the special casing, reclaim behaviour is
unpredictable as kswapd sometimes examines slab and sometimes does not
in a manner that is tricky to tune or analyse.
This patch removes the special casing. The downside is that this is not
a universal performance win. Some benchmarks that depend on the
residency of data when rereading metadata may see a regression when slab
reclaim is restored to its original behaviour. Similarly, some
benchmarks that only read-once or write-once may perform better when
page reclaim is too aggressive. The primary upside is that slab
shrinker is less surprising (arguably more sane but that's a matter of
opinion), behaves consistently regardless of the fragmentation state of
the system and properly obeys VM sysctls.
A fsmark benchmark configuration was constructed similar to what Dave
reported and is codified by the mmtest configuration
config-io-fsmark-small-file-stream. It was evaluated on a 1-socket
machine to avoid dealing with NUMA-related issues and the timing of
reclaim. The storage was an SSD Samsung Evo and a fresh trimmed XFS
filesystem was used for the test data.
This is not an exact replication of Dave's setup. The configuration
scales its parameters depending on the memory size of the SUT to behave
similarly across machines. The parameters mean the first sample
reported by fs_mark is using 50% of RAM which will barely be throttled
and look like a big outlier. Dave used fake NUMA to have multiple
kswapd instances which I didn't replicate. Finally, the number of
iterations differ from Dave's test as the target disk was not large
enough. While not identical, it should be representative.
fsmark
5.3.0-rc3 5.3.0-rc3
vanilla shrinker-v1r1
Min 1-files/sec 4444.80 ( 0.00%) 4765.60 ( 7.22%)
1st-qrtle 1-files/sec 5005.10 ( 0.00%) 5091.70 ( 1.73%)
2nd-qrtle 1-files/sec 4917.80 ( 0.00%) 4855.60 ( -1.26%)
3rd-qrtle 1-files/sec 4667.40 ( 0.00%) 4831.20 ( 3.51%)
Max-1 1-files/sec 11421.50 ( 0.00%) 9999.30 ( -12.45%)
Max-5 1-files/sec 11421.50 ( 0.00%) 9999.30 ( -12.45%)
Max-10 1-files/sec 11421.50 ( 0.00%) 9999.30 ( -12.45%)
Max-90 1-files/sec 4649.60 ( 0.00%) 4780.70 ( 2.82%)
Max-95 1-files/sec 4491.00 ( 0.00%) 4768.20 ( 6.17%)
Max-99 1-files/sec 4491.00 ( 0.00%) 4768.20 ( 6.17%)
Max 1-files/sec 11421.50 ( 0.00%) 9999.30 ( -12.45%)
Hmean 1-files/sec 5004.75 ( 0.00%) 5075.96 ( 1.42%)
Stddev 1-files/sec 1778.70 ( 0.00%) 1369.66 ( 23.00%)
CoeffVar 1-files/sec 33.70 ( 0.00%) 26.05 ( 22.71%)
BHmean-99 1-files/sec 5053.72 ( 0.00%) 5101.52 ( 0.95%)
BHmean-95 1-files/sec 5053.72 ( 0.00%) 5101.52 ( 0.95%)
BHmean-90 1-files/sec 5107.05 ( 0.00%) 5131.41 ( 0.48%)
BHmean-75 1-files/sec 5208.45 ( 0.00%) 5206.68 ( -0.03%)
BHmean-50 1-files/sec 5405.53 ( 0.00%) 5381.62 ( -0.44%)
BHmean-25 1-files/sec 6179.75 ( 0.00%) 6095.14 ( -1.37%)
5.3.0-rc3 5.3.0-rc3
vanillashrinker-v1r1
Duration User 501.82 497.29
Duration System 4401.44 4424.08
Duration Elapsed 8124.76 8358.05
This is showing a slight skew for the max result representing a large
outlier for the 1st, 2nd and 3rd quartile are similar indicating that
the bulk of the results show little difference. Note that an earlier
version of the fsmark configuration showed a regression but that
included more samples taken while memory was still filling.
Note that the elapsed time is higher. Part of this is that the
configuration included time to delete all the test files when the test
completes -- the test automation handles the possibility of testing
fsmark with multiple thread counts. Without the patch, many of these
objects would be memory resident which is part of what the patch is
addressing.
There are other important observations that justify the patch.
1. With the vanilla kernel, the number of dirty pages in the system is
very low for much of the test. With this patch, dirty pages is
generally kept at 10% which matches vm.dirty_background_ratio which
is normal expected historical behaviour.
2. With the vanilla kernel, the ratio of Slab/Pagecache is close to
0.95 for much of the test i.e. Slab is being left alone and
dominating memory consumption. With the patch applied, the ratio
varies between 0.35 and 0.45 with the bulk of the measured ratios
roughly half way between those values. This is a different balance to
what Dave reported but it was at least consistent.
3. Slabs are scanned throughout the entire test with the patch applied.
The vanille kernel has periods with no scan activity and then
relatively massive spikes.
4. Without the patch, kswapd scan rates are very variable. With the
patch, the scan rates remain quite steady.
4. Overall vmstats are closer to normal expectations
5.3.0-rc3 5.3.0-rc3
vanilla shrinker-v1r1
Ops Direct pages scanned 99388.00 328410.00
Ops Kswapd pages scanned 45382917.00 33451026.00
Ops Kswapd pages reclaimed 30869570.00 25239655.00
Ops Direct pages reclaimed 74131.00 5830.00
Ops Kswapd efficiency % 68.02 75.45
Ops Kswapd velocity 5585.75 4002.25
Ops Page reclaim immediate 1179721.00 430927.00
Ops Slabs scanned 62367361.00 73581394.00
Ops Direct inode steals 2103.00 1002.00
Ops Kswapd inode steals 570180.00 5183206.00
o Vanilla kernel is hitting direct reclaim more frequently,
not very much in absolute terms but the fact the patch
reduces it is interesting
o "Page reclaim immediate" in the vanilla kernel indicates
dirty pages are being encountered at the tail of the LRU.
This is generally bad and means in this case that the LRU
is not long enough for dirty pages to be cleaned by the
background flush in time. This is much reduced by the
patch.
o With the patch, kswapd is reclaiming 10 times more slab
pages than with the vanilla kernel. This is indicative
of the watermark boosting over-protecting slab
A more complete set of tests were run that were part of the basis for
introducing boosting and while there are some differences, they are well
within tolerances.
Bottom line, the special casing kswapd to avoid slab behaviour is
unpredictable and can lead to abnormal results for normal workloads.
This patch restores the expected behaviour that slab and page cache is
balanced consistently for a workload with a steady allocation ratio of
slab/pagecache pages. It also means that if there are workloads that
favour the preservation of slab over pagecache that it can be tuned via
vm.vfs_cache_pressure where as the vanilla kernel effectively ignores
the parameter when boosting is active.
Link: http://lkml.kernel.org/r/20190808182946.GM2739@techsingularity.net
Fixes: 1c30844d2d ("mm: reclaim small amounts of memory when an external fragmentation event occurs")
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: <stable@vger.kernel.org> [5.0+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Shakeel Butt reported premature oom on kernel with
"cgroup_disable=memory" since mem_cgroup_is_root() returns false even
though memcg is actually NULL. The drop_caches is also broken.
It is because commit aeed1d325d ("mm/vmscan.c: generalize
shrink_slab() calls in shrink_node()") removed the !memcg check before
!mem_cgroup_is_root(). And, surprisingly root memcg is allocated even
though memory cgroup is disabled by kernel boot parameter.
Add mem_cgroup_disabled() check to make reclaimer work as expected.
Link: http://lkml.kernel.org/r/1563385526-20805-1-git-send-email-yang.shi@linux.alibaba.com
Fixes: aeed1d325d ("mm/vmscan.c: generalize shrink_slab() calls in shrink_node()")
Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com>
Reported-by: Shakeel Butt <shakeelb@google.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Jan Hadrava <had@kam.mff.cuni.cz>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Roman Gushchin <guro@fb.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Qian Cai <cai@lca.pw>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: <stable@vger.kernel.org> [4.19+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Six sites are presently altering current->reclaim_state. There is a
risk that one function stomps on a caller's value. Use a helper
function to catch such errors.
Cc: Yafang Shao <laoar.shao@gmail.com>
Cc: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There are six different reclaim paths by now:
- kswapd reclaim path
- node reclaim path
- hibernate preallocate memory reclaim path
- direct reclaim path
- memcg reclaim path
- memcg softlimit reclaim path
The slab caches reclaimed in these paths are only calculated in the
above three paths.
There're some drawbacks if we don't calculate the reclaimed slab caches.
- The sc->nr_reclaimed isn't correct if there're some slab caches
relcaimed in this path.
- The slab caches may be reclaimed thoroughly if there're lots of
reclaimable slab caches and few page caches.
Let's take an easy example for this case. If one memcg is full of
slab caches and the limit of it is 512M, in other words there're
approximately 512M slab caches in this memcg. Then the limit of the
memcg is reached and the memcg reclaim begins, and then in this memcg
reclaim path it will continuesly reclaim the slab caches until the
sc->priority drops to 0. After this reclaim stops, you will find
there're few slab caches left, which is less than 20M in my test
case. While after this patch applied the number is greater than 300M
and the sc->priority only drops to 3.
Link: http://lkml.kernel.org/r/1561112086-6169-3-git-send-email-laoar.shao@gmail.com
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "mm/vmscan: calculate reclaimed slab in all reclaim paths".
This patchset is to fix the issues in doing shrink slab.
There're six different reclaim paths by now,
- kswapd reclaim path
- node reclaim path
- hibernate preallocate memory reclaim path
- direct reclaim path
- memcg reclaim path
- memcg softlimit reclaim path
The slab caches reclaimed in these paths are only calculated in the
above three paths. The issues are detailed explained in patch #2. We
should calculate the reclaimed slab caches in every reclaim path. In
order to do it, the struct reclaim_state is placed into the struct
shrink_control.
In node reclaim path, there'is another issue about shrinking slab, which
is adressed in "mm/vmscan: shrink slab in node reclaim"
(https://lore.kernel.org/linux-mm/1559874946-22960-1-git-send-email-laoar.shao@gmail.com/).
This patch (of 2):
The struct reclaim_state is used to record how many slab caches are
reclaimed in one reclaim path. The struct shrink_control is used to
control one reclaim path. So we'd better put reclaim_state into
shrink_control.
[laoar.shao@gmail.com: remove reclaim_state assignment from __perform_reclaim()]
Link: http://lkml.kernel.org/r/1561381582-13697-1-git-send-email-laoar.shao@gmail.com
Link: http://lkml.kernel.org/r/1561112086-6169-2-git-send-email-laoar.shao@gmail.com
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit bd4c82c22c ("mm, THP, swap: delay splitting THP after swapped
out"), THP can be swapped out in a whole. But, nr_reclaimed and some
other vm counters still get inc'ed by one even though a whole THP (512
pages) gets swapped out.
This doesn't make too much sense to memory reclaim.
For example, direct reclaim may just need reclaim SWAP_CLUSTER_MAX
pages, reclaiming one THP could fulfill it. But, if nr_reclaimed is not
increased correctly, direct reclaim may just waste time to reclaim more
pages, SWAP_CLUSTER_MAX * 512 pages in worst case.
And, it may cause pgsteal_{kswapd|direct} is greater than
pgscan_{kswapd|direct}, like the below:
pgsteal_kswapd 122933
pgsteal_direct 26600225
pgscan_kswapd 174153
pgscan_direct 14678312
nr_reclaimed and nr_scanned must be fixed in parallel otherwise it would
break some page reclaim logic, e.g.
vmpressure: this looks at the scanned/reclaimed ratio so it won't change
semantics as long as scanned & reclaimed are fixed in parallel.
compaction/reclaim: compaction wants a certain number of physical pages
freed up before going back to compacting.
kswapd priority raising: kswapd raises priority if we scan fewer pages
than the reclaim target (which itself is obviously expressed in order-0
pages). As a result, kswapd can falsely raise its aggressiveness even
when it's making great progress.
Other than nr_scanned and nr_reclaimed, some other counters, e.g.
pgactivate, nr_skipped, nr_ref_keep and nr_unmap_fail need to be fixed too
since they are user visible via cgroup, /proc/vmstat or trace points,
otherwise they would be underreported.
When isolating pages from LRUs, nr_taken has been accounted in base page,
but nr_scanned and nr_skipped are still accounted in THP. It doesn't make
too much sense too since this may cause trace point underreport the
numbers as well.
So accounting those counters in base page instead of accounting THP as one
page.
nr_dirty, nr_unqueued_dirty, nr_congested and nr_writeback are used by
file cache, so they are not impacted by THP swap.
This change may result in lower steal/scan ratio in some cases since THP
may get split during page reclaim, then a part of tail pages get reclaimed
instead of the whole 512 pages, but nr_scanned is accounted by 512,
particularly for direct reclaim. But, this should be not a significant
issue.
Link: http://lkml.kernel.org/r/1559025859-72759-2-git-send-email-yang.shi@linux.alibaba.com
Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com>
Reviewed-by: "Huang, Ying" <ying.huang@intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit 9092c71bb7 ("mm: use sc->priority for slab shrink targets") has
broken up the relationship between sc->nr_scanned and slab pressure.
The sc->nr_scanned can't double slab pressure anymore. So, it sounds no
sense to still keep sc->nr_scanned inc'ed. Actually, it would prevent
from adding pressure on slab shrink since excessive sc->nr_scanned would
prevent from scan->priority raise.
The bonnie test doesn't show this would change the behavior of slab
shrinkers.
w/ w/o
/sec %CP /sec %CP
Sequential delete: 3960.6 94.6 3997.6 96.2
Random delete: 2518 63.8 2561.6 64.6
The slight increase of "/sec" without the patch would be caused by the
slight increase of CPU usage.
Link: http://lkml.kernel.org/r/1559025859-72759-1-git-send-email-yang.shi@linux.alibaba.com
Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Hillf Danton <hdanton@sina.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When file refaults are detected and there are many inactive file pages,
the system never reclaim anonymous pages, the file pages are dropped
aggressively when there are still a lot of cold anonymous pages and
system thrashes. This issue impacts the performance of applications
with large executable, e.g. chrome.
With this patch, when file refault is detected, inactive_list_is_low()
always returns true for file pages in get_scan_count() to enable
scanning anonymous pages.
The problem can be reproduced by the following test program.
---8<---
void fallocate_file(const char *filename, off_t size)
{
struct stat st;
int fd;
if (!stat(filename, &st) && st.st_size >= size)
return;
fd = open(filename, O_WRONLY | O_CREAT, 0600);
if (fd < 0) {
perror("create file");
exit(1);
}
if (posix_fallocate(fd, 0, size)) {
perror("fallocate");
exit(1);
}
close(fd);
}
long *alloc_anon(long size)
{
long *start = malloc(size);
memset(start, 1, size);
return start;
}
long access_file(const char *filename, long size, long rounds)
{
int fd, i;
volatile char *start1, *end1, *start2;
const int page_size = getpagesize();
long sum = 0;
fd = open(filename, O_RDONLY);
if (fd == -1) {
perror("open");
exit(1);
}
/*
* Some applications, e.g. chrome, use a lot of executable file
* pages, map some of the pages with PROT_EXEC flag to simulate
* the behavior.
*/
start1 = mmap(NULL, size / 2, PROT_READ | PROT_EXEC, MAP_SHARED,
fd, 0);
if (start1 == MAP_FAILED) {
perror("mmap");
exit(1);
}
end1 = start1 + size / 2;
start2 = mmap(NULL, size / 2, PROT_READ, MAP_SHARED, fd, size / 2);
if (start2 == MAP_FAILED) {
perror("mmap");
exit(1);
}
for (i = 0; i < rounds; ++i) {
struct timeval before, after;
volatile char *ptr1 = start1, *ptr2 = start2;
gettimeofday(&before, NULL);
for (; ptr1 < end1; ptr1 += page_size, ptr2 += page_size)
sum += *ptr1 + *ptr2;
gettimeofday(&after, NULL);
printf("File access time, round %d: %f (sec)
", i,
(after.tv_sec - before.tv_sec) +
(after.tv_usec - before.tv_usec) / 1000000.0);
}
return sum;
}
int main(int argc, char *argv[])
{
const long MB = 1024 * 1024;
long anon_mb, file_mb, file_rounds;
const char filename[] = "large";
long *ret1;
long ret2;
if (argc != 4) {
printf("usage: thrash ANON_MB FILE_MB FILE_ROUNDS
");
exit(0);
}
anon_mb = atoi(argv[1]);
file_mb = atoi(argv[2]);
file_rounds = atoi(argv[3]);
fallocate_file(filename, file_mb * MB);
printf("Allocate %ld MB anonymous pages
", anon_mb);
ret1 = alloc_anon(anon_mb * MB);
printf("Access %ld MB file pages
", file_mb);
ret2 = access_file(filename, file_mb * MB, file_rounds);
printf("Print result to prevent optimization: %ld
",
*ret1 + ret2);
return 0;
}
---8<---
Running the test program on 2GB RAM VM with kernel 5.2.0-rc5, the program
fills ram with 2048 MB memory, access a 200 MB file for 10 times. Without
this patch, the file cache is dropped aggresively and every access to the
file is from disk.
$ ./thrash 2048 200 10
Allocate 2048 MB anonymous pages
Access 200 MB file pages
File access time, round 0: 2.489316 (sec)
File access time, round 1: 2.581277 (sec)
File access time, round 2: 2.487624 (sec)
File access time, round 3: 2.449100 (sec)
File access time, round 4: 2.420423 (sec)
File access time, round 5: 2.343411 (sec)
File access time, round 6: 2.454833 (sec)
File access time, round 7: 2.483398 (sec)
File access time, round 8: 2.572701 (sec)
File access time, round 9: 2.493014 (sec)
With this patch, these file pages can be cached.
$ ./thrash 2048 200 10
Allocate 2048 MB anonymous pages
Access 200 MB file pages
File access time, round 0: 2.475189 (sec)
File access time, round 1: 2.440777 (sec)
File access time, round 2: 2.411671 (sec)
File access time, round 3: 1.955267 (sec)
File access time, round 4: 0.029924 (sec)
File access time, round 5: 0.000808 (sec)
File access time, round 6: 0.000771 (sec)
File access time, round 7: 0.000746 (sec)
File access time, round 8: 0.000738 (sec)
File access time, round 9: 0.000747 (sec)
Checked the swap out stats during the test [1], 19006 pages swapped out
with this patch, 3418 pages swapped out without this patch. There are
more swap out, but I think it's within reasonable range when file backed
data set doesn't fit into the memory.
$ ./thrash 2000 100 2100 5 1 # ANON_MB FILE_EXEC FILE_NOEXEC ROUNDS
PROCESSES Allocate 2000 MB anonymous pages active_anon: 1613644,
inactive_anon: 348656, active_file: 892, inactive_file: 1384 (kB)
pswpout: 7972443, pgpgin: 478615246 Access 100 MB executable file pages
Access 2100 MB regular file pages File access time, round 0: 12.165,
(sec) active_anon: 1433788, inactive_anon: 478116, active_file: 17896,
inactive_file: 24328 (kB) File access time, round 1: 11.493, (sec)
active_anon: 1430576, inactive_anon: 477144, active_file: 25440,
inactive_file: 26172 (kB) File access time, round 2: 11.455, (sec)
active_anon: 1427436, inactive_anon: 476060, active_file: 21112,
inactive_file: 28808 (kB) File access time, round 3: 11.454, (sec)
active_anon: 1420444, inactive_anon: 473632, active_file: 23216,
inactive_file: 35036 (kB) File access time, round 4: 11.479, (sec)
active_anon: 1413964, inactive_anon: 471460, active_file: 31728,
inactive_file: 32224 (kB) pswpout: 7991449 (+ 19006), pgpgin: 489924366
(+ 11309120)
With 4 processes accessing non-overlapping parts of a large file, 30316
pages swapped out with this patch, 5152 pages swapped out without this
patch. The swapout number is small comparing to pgpgin.
[1]: https://github.com/vovo/testing/blob/master/mem_thrash.c
Link: http://lkml.kernel.org/r/20190701081038.GA83398@google.com
Fixes: e986850598 ("mm,vmscan: only evict file pages when we have plenty")
Fixes: 7c5bd705d8 ("mm: memcg: only evict file pages when we have plenty")
Signed-off-by: Kuo-Hsin Yang <vovoy@chromium.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Sonny Rao <sonnyrao@chromium.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Rik van Riel <riel@redhat.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: <stable@vger.kernel.org> [4.12+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In production we have noticed hard lockups on large machines running
large jobs due to kswaps hoarding lru lock within isolate_lru_pages when
sc->reclaim_idx is 0 which is a small zone. The lru was couple hundred
GiBs and the condition (page_zonenum(page) > sc->reclaim_idx) in
isolate_lru_pages() was basically skipping GiBs of pages while holding
the LRU spinlock with interrupt disabled.
On further inspection, it seems like there are two issues:
(1) If kswapd on the return from balance_pgdat() could not sleep (i.e.
node is still unbalanced), the classzone_idx is unintentionally set
to 0 and the whole reclaim cycle of kswapd will try to reclaim only
the lowest and smallest zone while traversing the whole memory.
(2) Fundamentally isolate_lru_pages() is really bad when the
allocation has woken kswapd for a smaller zone on a very large machine
running very large jobs. It can hoard the LRU spinlock while skipping
over 100s of GiBs of pages.
This patch only fixes (1). (2) needs a more fundamental solution. To
fix (1), in the kswapd context, if pgdat->kswapd_classzone_idx is
invalid use the classzone_idx of the previous kswapd loop otherwise use
the one the waker has requested.
Link: http://lkml.kernel.org/r/20190701201847.251028-1-shakeelb@google.com
Fixes: e716f2eb24 ("mm, vmscan: prevent kswapd sleeping prematurely due to mismatched classzone_idx")
Signed-off-by: Shakeel Butt <shakeelb@google.com>
Reviewed-by: Yang Shi <yang.shi@linux.alibaba.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Roman Gushchin <guro@fb.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There was the below bug report from Wu Fangsuo.
On the CMA allocation path, isolate_migratepages_range() could isolate
unevictable LRU pages and reclaim_clean_page_from_list() can try to
reclaim them if they are clean file-backed pages.
page:ffffffbf02f33b40 count:86 mapcount:84 mapping:ffffffc08fa7a810 index:0x24
flags: 0x19040c(referenced|uptodate|arch_1|mappedtodisk|unevictable|mlocked)
raw: 000000000019040c ffffffc08fa7a810 0000000000000024 0000005600000053
raw: ffffffc009b05b20 ffffffc009b05b20 0000000000000000 ffffffc09bf3ee80
page dumped because: VM_BUG_ON_PAGE(PageLRU(page) || PageUnevictable(page))
page->mem_cgroup:ffffffc09bf3ee80
------------[ cut here ]------------
kernel BUG at /home/build/farmland/adroid9.0/kernel/linux/mm/vmscan.c:1350!
Internal error: Oops - BUG: 0 [#1] PREEMPT SMP
Modules linked in:
CPU: 0 PID: 7125 Comm: syz-executor Tainted: G S 4.14.81 #3
Hardware name: ASR AQUILAC EVB (DT)
task: ffffffc00a54cd00 task.stack: ffffffc009b00000
PC is at shrink_page_list+0x1998/0x3240
LR is at shrink_page_list+0x1998/0x3240
pc : [<ffffff90083a2158>] lr : [<ffffff90083a2158>] pstate: 60400045
sp : ffffffc009b05940
..
shrink_page_list+0x1998/0x3240
reclaim_clean_pages_from_list+0x3c0/0x4f0
alloc_contig_range+0x3bc/0x650
cma_alloc+0x214/0x668
ion_cma_allocate+0x98/0x1d8
ion_alloc+0x200/0x7e0
ion_ioctl+0x18c/0x378
do_vfs_ioctl+0x17c/0x1780
SyS_ioctl+0xac/0xc0
Wu found it's due to commit ad6b67041a ("mm: remove SWAP_MLOCK in
ttu"). Before that, unevictable pages go to cull_mlocked so that we
can't reach the VM_BUG_ON_PAGE line.
To fix the issue, this patch filters out unevictable LRU pages from the
reclaim_clean_pages_from_list in CMA.
Link: http://lkml.kernel.org/r/20190524071114.74202-1-minchan@kernel.org
Fixes: ad6b67041a ("mm: remove SWAP_MLOCK in ttu")
Signed-off-by: Minchan Kim <minchan@kernel.org>
Reported-by: Wu Fangsuo <fangsuowu@asrmicro.com>
Debugged-by: Wu Fangsuo <fangsuowu@asrmicro.com>
Tested-by: Wu Fangsuo <fangsuowu@asrmicro.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Pankaj Suryawanshi <pankaj.suryawanshi@einfochips.com>
Cc: <stable@vger.kernel.org> [4.12+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Johannes pointed out that after commit 886cf1901d ("mm: move
recent_rotated pages calculation to shrink_inactive_list()") we lost all
zone_reclaim_stat::recent_rotated history.
This fixes it.
Link: http://lkml.kernel.org/r/155905972210.26456.11178359431724024112.stgit@localhost.localdomain
Fixes: 886cf1901d ("mm: move recent_rotated pages calculation to shrink_inactive_list()")
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Reported-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Daniel Jordan <daniel.m.jordan@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "mm: memcontrol: memory.stat cost & correctness".
The cgroup memory.stat file holds recursive statistics for the entire
subtree. The current implementation does this tree walk on-demand
whenever the file is read. This is giving us problems in production.
1. The cost of aggregating the statistics on-demand is high. A lot of
system service cgroups are mostly idle and their stats don't change
between reads, yet we always have to check them. There are also always
some lazily-dying cgroups sitting around that are pinned by a handful
of remaining page cache; the same applies to them.
In an application that periodically monitors memory.stat in our
fleet, we have seen the aggregation consume up to 5% CPU time.
2. When cgroups die and disappear from the cgroup tree, so do their
accumulated vm events. The result is that the event counters at
higher-level cgroups can go backwards and confuse some of our
automation, let alone people looking at the graphs over time.
To address both issues, this patch series changes the stat
implementation to spill counts upwards when the counters change.
The upward spilling is batched using the existing per-cpu cache. In a
sparse file stress test with 5 level cgroup nesting, the additional cost
of the flushing was negligible (a little under 1% of CPU at 100% CPU
utilization, compared to the 5% of reading memory.stat during regular
operation).
This patch (of 4):
memcg_page_state(), lruvec_page_state(), memcg_sum_events() are
currently returning the state of the local memcg or lruvec, not the
recursive state.
In practice there is a demand for both versions, although the callers
that want the recursive counts currently sum them up by hand.
Per default, cgroups are considered recursive entities and generally we
expect more users of the recursive counters, with the local counts being
special cases. To reflect that in the name, add a _local suffix to the
current implementations.
The following patch will re-incarnate these functions with recursive
semantics, but with an O(1) implementation.
[hannes@cmpxchg.org: fix bisection hole]
Link: http://lkml.kernel.org/r/20190417160347.GC23013@cmpxchg.org
Link: http://lkml.kernel.org/r/20190412151507.2769-2-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Reviewed-by: Roman Gushchin <guro@fb.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We can use __count_memcg_events() directly because this callsite is alreay
protected by spin_lock_irq().
Link: http://lkml.kernel.org/r/1556093494-30798-1-git-send-email-laoar.shao@gmail.com
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This merges together duplicated patterns of code. Also, replace
count_memcg_events() with its irq-careless namesake, because they are
already called in interrupts disabled context.
Link: http://lkml.kernel.org/r/2ece1df4-2989-bc9b-6172-61e9fdde5bfd@virtuozzo.com
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There are three tracepoints using this template, which are
mm_vmscan_direct_reclaim_begin,
mm_vmscan_memcg_reclaim_begin,
mm_vmscan_memcg_softlimit_reclaim_begin.
Regarding mm_vmscan_direct_reclaim_begin,
sc.may_writepage is !laptop_mode, that's a static setting, and
reclaim_idx is derived from gfp_mask which is already show in this
tracepoint.
Regarding mm_vmscan_memcg_reclaim_begin,
may_writepage is !laptop_mode too, and reclaim_idx is (MAX_NR_ZONES-1),
which are both static value.
mm_vmscan_memcg_softlimit_reclaim_begin is the same with
mm_vmscan_memcg_reclaim_begin.
So we can drop them all.
Link: http://lkml.kernel.org/r/1553736322-32235-1-git-send-email-laoar.shao@gmail.com
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Instead of adding up the zone counters, use lruvec_page_state() to get the
node state directly. This is a bit cheaper and more stream-lined.
Link: http://lkml.kernel.org/r/20190228163020.24100-3-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Roman Gushchin <guro@fb.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The page alloc fast path it may perform node reclaim, which may cause a
latency spike. We should add tracepoint for this event, and also measure
the latency it causes.
So bellow two tracepoints are introduced,
mm_vmscan_node_reclaim_begin
mm_vmscan_node_reclaim_end
Link: http://lkml.kernel.org/r/1551421452-5385-1-git-send-email-laoar.shao@gmail.com
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Souptick Joarder <jrdr.linux@gmail.com>
Cc: <shaoyafang@didiglobal.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This combines two similar functions move_active_pages_to_lru() and
putback_inactive_pages() into single move_pages_to_lru(). This remove
duplicate code and makes object file size smaller.
Before:
text data bss dec hex filename
57082 4732 128 61942 f1f6 mm/vmscan.o
After:
text data bss dec hex filename
55112 4600 128 59840 e9c0 mm/vmscan.o
Note, that now we are checking for !page_evictable() coming from
shrink_active_list(), which shouldn't change any behavior since that path
works with evictable pages only.
Link: http://lkml.kernel.org/r/155290129627.31489.8321971028677203248.stgit@localhost.localdomain
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We may use input argument list as output argument too. This makes the
function more similar to putback_inactive_pages().
Link: http://lkml.kernel.org/r/155290129079.31489.16180612694090502942.stgit@localhost.localdomain
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "mm: Generalize putback functions"]
putback_inactive_pages() and move_active_pages_to_lru() are almost
similar, so this patchset merges them ina single function.
This patch (of 4):
The patch moves the calculation from putback_inactive_pages() to
shrink_inactive_list(). This makes putback_inactive_pages() looking more
similar to move_active_pages_to_lru().
To do that, we account activated pages in reclaim_stat::nr_activate.
Since a page may change its LRU type from anon to file cache inside
shrink_page_list() (see ClearPageSwapBacked()), we have to account pages
for the both types. So, nr_activate becomes an array.
Previously we used nr_activate to account PGACTIVATE events, but now we
account them into pgactivate variable (since they are about number of
pages in general, not about sum of hpage_nr_pages).
Link: http://lkml.kernel.org/r/155290127956.31489.3393586616054413298.stgit@localhost.localdomain
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Merge tag 'printk-for-5.2' of git://git.kernel.org/pub/scm/linux/kernel/git/pmladek/printk
Pull printk updates from Petr Mladek:
- Allow state reset of printk_once() calls.
- Prevent crashes when dereferencing invalid pointers in vsprintf().
Only the first byte is checked for simplicity.
- Make vsprintf warnings consistent and inlined.
- Treewide conversion of obsolete %pf, %pF to %ps, %pF printf
modifiers.
- Some clean up of vsprintf and test_printf code.
* tag 'printk-for-5.2' of git://git.kernel.org/pub/scm/linux/kernel/git/pmladek/printk:
lib/vsprintf: Make function pointer_string static
vsprintf: Limit the length of inlined error messages
vsprintf: Avoid confusion between invalid address and value
vsprintf: Prevent crash when dereferencing invalid pointers
vsprintf: Consolidate handling of unknown pointer specifiers
vsprintf: Factor out %pO handler as kobject_string()
vsprintf: Factor out %pV handler as va_format()
vsprintf: Factor out %p[iI] handler as ip_addr_string()
vsprintf: Do not check address of well-known strings
vsprintf: Consistent %pK handling for kptr_restrict == 0
vsprintf: Shuffle restricted_pointer()
printk: Tie printk_once / printk_deferred_once into .data.once for reset
treewide: Switch printk users from %pf and %pF to %ps and %pS, respectively
lib/test_printf: Switch to bitmap_zalloc()
During !CONFIG_CGROUP reclaim, we expand the inactive list size if it's
thrashing on the node that is about to be reclaimed. But when cgroups
are enabled, we suddenly ignore the node scope and use the cgroup scope
only. The result is that pressure bleeds between NUMA nodes depending
on whether cgroups are merely compiled into Linux. This behavioral
difference is unexpected and undesirable.
When the refault adaptivity of the inactive list was first introduced,
there were no statistics at the lruvec level - the intersection of node
and memcg - so it was better than nothing.
But now that we have that infrastructure, use lruvec_page_state() to
make the list balancing decision always NUMA aware.
[hannes@cmpxchg.org: fix bisection hole]
Link: http://lkml.kernel.org/r/20190417155241.GB23013@cmpxchg.org
Link: http://lkml.kernel.org/r/20190412144438.2645-1-hannes@cmpxchg.org
Fixes: 2a2e48854d ("mm: vmscan: fix IO/refault regression in cache workingset transition")
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We have common pattern to access lru_lock from a page pointer:
zone_lru_lock(page_zone(page))
Which is silly, because it unfolds to this:
&NODE_DATA(page_to_nid(page))->node_zones[page_zonenum(page)]->zone_pgdat->lru_lock
while we can simply do
&NODE_DATA(page_to_nid(page))->lru_lock
Remove zone_lru_lock() function, since it's only complicate things. Use
'page_pgdat(page)->lru_lock' pattern instead.
[aryabinin@virtuozzo.com: a slightly better version of __split_huge_page()]
Link: http://lkml.kernel.org/r/20190301121651.7741-1-aryabinin@virtuozzo.com
Link: http://lkml.kernel.org/r/20190228083329.31892-2-aryabinin@virtuozzo.com
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: William Kucharski <william.kucharski@oracle.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
workingset_eviction() doesn't use and never did use the @mapping
argument. Remove it.
Link: http://lkml.kernel.org/r/20190228083329.31892-1-aryabinin@virtuozzo.com
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Rik van Riel <riel@surriel.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: William Kucharski <william.kucharski@oracle.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
On path shrink_inactive_list() ---> shrink_page_list() we allocate stack
variables for the statistics twice. This is completely useless, and
this just consumes stack much more, then we really need.
The patch kills duplicate stack variables from shrink_page_list(), and
this reduce stack usage and object file size significantly:
Stack usage:
Before: vmscan.c:1122:22:shrink_page_list 648 static
After: vmscan.c:1122:22:shrink_page_list 616 static
Size of vmscan.o:
text data bss dec hex filename
Before: 56866 4720 128 61714 f112 mm/vmscan.o
After: 56770 4720 128 61618 f0b2 mm/vmscan.o
Link: http://lkml.kernel.org/r/154894900030.5211.12104993874109647641.stgit@localhost.localdomain
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In current implementation, both kswapd and direct reclaim has to iterate
all mem cgroups. It is not a problem before offline mem cgroups could
be iterated. But, currently with iterating offline mem cgroups, it
could be very time consuming. In our workloads, we saw over 400K mem
cgroups accumulated in some cases, only a few hundred are online memcgs.
Although kswapd could help out to reduce the number of memcgs, direct
reclaim still get hit with iterating a number of offline memcgs in some
cases. We experienced the responsiveness problems due to this
occassionally.
A simple test with pref shows it may take around 220ms to iterate 8K
memcgs in direct reclaim:
dd 13873 [011] 578.542919: vmscan:mm_vmscan_direct_reclaim_begin
dd 13873 [011] 578.758689: vmscan:mm_vmscan_direct_reclaim_end
So for 400K, it may take around 11 seconds to iterate all memcgs.
Here just break the iteration once it reclaims enough pages as what
memcg direct reclaim does. This may hurt the fairness among memcgs.
But the cached iterator cookie could help to achieve the fairness more
or less.
Link: http://lkml.kernel.org/r/1548799877-10949-1-git-send-email-yang.shi@linux.alibaba.com
Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We may simply check for sc->may_unmap in isolate_lru_pages() instead of
doing that in both of its callers.
Link: http://lkml.kernel.org/r/154748280735.29962.15867846875217618569.stgit@localhost.localdomain
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
No functional change.
Link: http://lkml.kernel.org/r/20190118235123.27843-1-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Pekka Enberg <penberg@kernel.org>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This reverts commit 172b06c32b ("mm: slowly shrink slabs with a
relatively small number of objects").
This change changes the agressiveness of shrinker reclaim, causing small
cache and low priority reclaim to greatly increase scanning pressure on
small caches. As a result, light memory pressure has a disproportionate
affect on small caches, and causes large caches to be reclaimed much
faster than previously.
As a result, it greatly perturbs the delicate balance of the VFS caches
(dentry/inode vs file page cache) such that the inode/dentry caches are
reclaimed much, much faster than the page cache and this drives us into
several other caching imbalance related problems.
As such, this is a bad change and needs to be reverted.
[ Needs some massaging to retain the later seekless shrinker
modifications.]
Link: http://lkml.kernel.org/r/20190130041707.27750-3-david@fromorbit.com
Fixes: 172b06c32b ("mm: slowly shrink slabs with a relatively small number of objects")
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Cc: Wolfgang Walter <linux@stwm.de>
Cc: Roman Gushchin <guro@fb.com>
Cc: Spock <dairinin@gmail.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Waiting on a page migration entry has used wait_on_page_locked() all along
since 2006: but you cannot safely wait_on_page_locked() without holding a
reference to the page, and that extra reference is enough to make
migrate_page_move_mapping() fail with -EAGAIN, when a racing task faults
on the entry before migrate_page_move_mapping() gets there.
And that failure is retried nine times, amplifying the pain when trying to
migrate a popular page. With a single persistent faulter, migration
sometimes succeeds; with two or three concurrent faulters, success becomes
much less likely (and the more the page was mapped, the worse the overhead
of unmapping and remapping it on each try).
This is especially a problem for memory offlining, where the outer level
retries forever (or until terminated from userspace), because a heavy
refault workload can trigger an endless loop of migration failures.
wait_on_page_locked() is the wrong tool for the job.
David Herrmann (but was he the first?) noticed this issue in 2014:
https://marc.info/?l=linux-mm&m=140110465608116&w=2
Tim Chen started a thread in August 2017 which appears relevant:
https://marc.info/?l=linux-mm&m=150275941014915&w=2 where Kan Liang went
on to implicate __migration_entry_wait():
https://marc.info/?l=linux-mm&m=150300268411980&w=2 and the thread ended
up with the v4.14 commits: 2554db9165 ("sched/wait: Break up long wake
list walk") 11a19c7b09 ("sched/wait: Introduce wakeup boomark in
wake_up_page_bit")
Baoquan He reported "Memory hotplug softlock issue" 14 November 2018:
https://marc.info/?l=linux-mm&m=154217936431300&w=2
We have all assumed that it is essential to hold a page reference while
waiting on a page lock: partly to guarantee that there is still a struct
page when MEMORY_HOTREMOVE is configured, but also to protect against
reuse of the struct page going to someone who then holds the page locked
indefinitely, when the waiter can reasonably expect timely unlocking.
But in fact, so long as wait_on_page_bit_common() does the put_page(), and
is careful not to rely on struct page contents thereafter, there is no
need to hold a reference to the page while waiting on it. That does mean
that this case cannot go back through the loop: but that's fine for the
page migration case, and even if used more widely, is limited by the "Stop
walking if it's locked" optimization in wake_page_function().
Add interface put_and_wait_on_page_locked() to do this, using "behavior"
enum in place of "lock" arg to wait_on_page_bit_common() to implement it.
No interruptible or killable variant needed yet, but they might follow: I
have a vague notion that reporting -EINTR should take precedence over
return from wait_on_page_bit_common() without knowing the page state, so
arrange it accordingly - but that may be nothing but pedantic.
__migration_entry_wait() still has to take a brief reference to the page,
prior to calling put_and_wait_on_page_locked(): but now that it is dropped
before waiting, the chance of impeding page migration is very much
reduced. Should we perhaps disable preemption across this?
shrink_page_list()'s __ClearPageLocked(): that was a surprise! This
survived a lot of testing before that showed up. PageWaiters may have
been set by wait_on_page_bit_common(), and the reference dropped, just
before shrink_page_list() succeeds in freezing its last page reference: in
such a case, unlock_page() must be used. Follow the suggestion from
Michal Hocko, just revert a978d6f521 ("mm: unlockless reclaim") now:
that optimization predates PageWaiters, and won't buy much these days; but
we can reinstate it for the !PageWaiters case if anyone notices.
It does raise the question: should vmscan.c's is_page_cache_freeable() and
__remove_mapping() now treat a PageWaiters page as if an extra reference
were held? Perhaps, but I don't think it matters much, since
shrink_page_list() already had to win its trylock_page(), so waiters are
not very common there: I noticed no difference when trying the bigger
change, and it's surely not needed while put_and_wait_on_page_locked() is
only used for page migration.
[willy@infradead.org: add put_and_wait_on_page_locked() kerneldoc]
Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1811261121330.1116@eggly.anvils
Signed-off-by: Hugh Dickins <hughd@google.com>
Reported-by: Baoquan He <bhe@redhat.com>
Tested-by: Baoquan He <bhe@redhat.com>
Reviewed-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: David Herrmann <dh.herrmann@gmail.com>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Nick Piggin <npiggin@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
An external fragmentation event was previously described as
When the page allocator fragments memory, it records the event using
the mm_page_alloc_extfrag event. If the fallback_order is smaller
than a pageblock order (order-9 on 64-bit x86) then it's considered
an event that will cause external fragmentation issues in the future.
The kernel reduces the probability of such events by increasing the
watermark sizes by calling set_recommended_min_free_kbytes early in the
lifetime of the system. This works reasonably well in general but if
there are enough sparsely populated pageblocks then the problem can still
occur as enough memory is free overall and kswapd stays asleep.
This patch introduces a watermark_boost_factor sysctl that allows a zone
watermark to be temporarily boosted when an external fragmentation causing
events occurs. The boosting will stall allocations that would decrease
free memory below the boosted low watermark and kswapd is woken if the
calling context allows to reclaim an amount of memory relative to the size
of the high watermark and the watermark_boost_factor until the boost is
cleared. When kswapd finishes, it wakes kcompactd at the pageblock order
to clean some of the pageblocks that may have been affected by the
fragmentation event. kswapd avoids any writeback, slab shrinkage and swap
from reclaim context during this operation to avoid excessive system
disruption in the name of fragmentation avoidance. Care is taken so that
kswapd will do normal reclaim work if the system is really low on memory.
This was evaluated using the same workloads as "mm, page_alloc: Spread
allocations across zones before introducing fragmentation".
1-socket Skylake machine
config-global-dhp__workload_thpfioscale XFS (no special madvise)
4 fio threads, 1 THP allocating thread
--------------------------------------
4.20-rc3 extfrag events < order 9: 804694
4.20-rc3+patch: 408912 (49% reduction)
4.20-rc3+patch1-4: 18421 (98% reduction)
4.20.0-rc3 4.20.0-rc3
lowzone-v5r8 boost-v5r8
Amean fault-base-1 653.58 ( 0.00%) 652.71 ( 0.13%)
Amean fault-huge-1 0.00 ( 0.00%) 178.93 * -99.00%*
4.20.0-rc3 4.20.0-rc3
lowzone-v5r8 boost-v5r8
Percentage huge-1 0.00 ( 0.00%) 5.12 ( 100.00%)
Note that external fragmentation causing events are massively reduced by
this path whether in comparison to the previous kernel or the vanilla
kernel. The fault latency for huge pages appears to be increased but that
is only because THP allocations were successful with the patch applied.
1-socket Skylake machine
global-dhp__workload_thpfioscale-madvhugepage-xfs (MADV_HUGEPAGE)
-----------------------------------------------------------------
4.20-rc3 extfrag events < order 9: 291392
4.20-rc3+patch: 191187 (34% reduction)
4.20-rc3+patch1-4: 13464 (95% reduction)
thpfioscale Fault Latencies
4.20.0-rc3 4.20.0-rc3
lowzone-v5r8 boost-v5r8
Min fault-base-1 912.00 ( 0.00%) 905.00 ( 0.77%)
Min fault-huge-1 127.00 ( 0.00%) 135.00 ( -6.30%)
Amean fault-base-1 1467.55 ( 0.00%) 1481.67 ( -0.96%)
Amean fault-huge-1 1127.11 ( 0.00%) 1063.88 * 5.61%*
4.20.0-rc3 4.20.0-rc3
lowzone-v5r8 boost-v5r8
Percentage huge-1 77.64 ( 0.00%) 83.46 ( 7.49%)
As before, massive reduction in external fragmentation events, some jitter
on latencies and an increase in THP allocation success rates.
2-socket Haswell machine
config-global-dhp__workload_thpfioscale XFS (no special madvise)
4 fio threads, 5 THP allocating threads
----------------------------------------------------------------
4.20-rc3 extfrag events < order 9: 215698
4.20-rc3+patch: 200210 (7% reduction)
4.20-rc3+patch1-4: 14263 (93% reduction)
4.20.0-rc3 4.20.0-rc3
lowzone-v5r8 boost-v5r8
Amean fault-base-5 1346.45 ( 0.00%) 1306.87 ( 2.94%)
Amean fault-huge-5 3418.60 ( 0.00%) 1348.94 ( 60.54%)
4.20.0-rc3 4.20.0-rc3
lowzone-v5r8 boost-v5r8
Percentage huge-5 0.78 ( 0.00%) 7.91 ( 910.64%)
There is a 93% reduction in fragmentation causing events, there is a big
reduction in the huge page fault latency and allocation success rate is
higher.
2-socket Haswell machine
global-dhp__workload_thpfioscale-madvhugepage-xfs (MADV_HUGEPAGE)
-----------------------------------------------------------------
4.20-rc3 extfrag events < order 9: 166352
4.20-rc3+patch: 147463 (11% reduction)
4.20-rc3+patch1-4: 11095 (93% reduction)
thpfioscale Fault Latencies
4.20.0-rc3 4.20.0-rc3
lowzone-v5r8 boost-v5r8
Amean fault-base-5 6217.43 ( 0.00%) 7419.67 * -19.34%*
Amean fault-huge-5 3163.33 ( 0.00%) 3263.80 ( -3.18%)
4.20.0-rc3 4.20.0-rc3
lowzone-v5r8 boost-v5r8
Percentage huge-5 95.14 ( 0.00%) 87.98 ( -7.53%)
There is a large reduction in fragmentation events with some jitter around
the latencies and success rates. As before, the high THP allocation
success rate does mean the system is under a lot of pressure. However, as
the fragmentation events are reduced, it would be expected that the
long-term allocation success rate would be higher.
Link: http://lkml.kernel.org/r/20181123114528.28802-5-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Zi Yan <zi.yan@cs.rutgers.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The i915 driver uses shmemfs to allocate backing storage for gem
objects. These shmemfs pages can be pinned (increased ref count) by
shmem_read_mapping_page_gfp(). When a lot of pages are pinned, vmscan
wastes a lot of time scanning these pinned pages. In some extreme case,
all pages in the inactive anon lru are pinned, and only the inactive
anon lru is scanned due to inactive_ratio, the system cannot swap and
invokes the oom-killer. Mark these pinned pages as unevictable to speed
up vmscan.
Export pagevec API check_move_unevictable_pages().
This patch was inspired by Chris Wilson's change [1].
[1]: https://patchwork.kernel.org/patch/9768741/
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dave Hansen <dave.hansen@intel.com>
Signed-off-by: Kuo-Hsin Yang <vovoy@chromium.org>
Acked-by: Michal Hocko <mhocko@suse.com> # mm part
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Acked-by: Dave Hansen <dave.hansen@intel.com>
Acked-by: Andrew Morton <akpm@linux-foundation.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20181106132324.17390-1-chris@chris-wilson.co.uk
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Pull XArray conversion from Matthew Wilcox:
"The XArray provides an improved interface to the radix tree data
structure, providing locking as part of the API, specifying GFP flags
at allocation time, eliminating preloading, less re-walking the tree,
more efficient iterations and not exposing RCU-protected pointers to
its users.
This patch set
1. Introduces the XArray implementation
2. Converts the pagecache to use it
3. Converts memremap to use it
The page cache is the most complex and important user of the radix
tree, so converting it was most important. Converting the memremap
code removes the only other user of the multiorder code, which allows
us to remove the radix tree code that supported it.
I have 40+ followup patches to convert many other users of the radix
tree over to the XArray, but I'd like to get this part in first. The
other conversions haven't been in linux-next and aren't suitable for
applying yet, but you can see them in the xarray-conv branch if you're
interested"
* 'xarray' of git://git.infradead.org/users/willy/linux-dax: (90 commits)
radix tree: Remove multiorder support
radix tree test: Convert multiorder tests to XArray
radix tree tests: Convert item_delete_rcu to XArray
radix tree tests: Convert item_kill_tree to XArray
radix tree tests: Move item_insert_order
radix tree test suite: Remove multiorder benchmarking
radix tree test suite: Remove __item_insert
memremap: Convert to XArray
xarray: Add range store functionality
xarray: Move multiorder_check to in-kernel tests
xarray: Move multiorder_shrink to kernel tests
xarray: Move multiorder account test in-kernel
radix tree test suite: Convert iteration test to XArray
radix tree test suite: Convert tag_tagged_items to XArray
radix tree: Remove radix_tree_clear_tags
radix tree: Remove radix_tree_maybe_preload_order
radix tree: Remove split/join code
radix tree: Remove radix_tree_update_node_t
page cache: Finish XArray conversion
dax: Convert page fault handlers to XArray
...
The page cache and most shrinkable slab caches hold data that has been
read from disk, but there are some caches that only cache CPU work, such
as the dentry and inode caches of procfs and sysfs, as well as the subset
of radix tree nodes that track non-resident page cache.
Currently, all these are shrunk at the same rate: using DEFAULT_SEEKS for
the shrinker's seeks setting tells the reclaim algorithm that for every
two page cache pages scanned it should scan one slab object.
This is a bogus setting. A virtual inode that required no IO to create is
not twice as valuable as a page cache page; shadow cache entries with
eviction distances beyond the size of memory aren't either.
In most cases, the behavior in practice is still fine. Such virtual
caches don't tend to grow and assert themselves aggressively, and usually
get picked up before they cause problems. But there are scenarios where
that's not true.
Our database workloads suffer from two of those. For one, their file
workingset is several times bigger than available memory, which has the
kernel aggressively create shadow page cache entries for the non-resident
parts of it. The workingset code does tell the VM that most of these are
expendable, but the VM ends up balancing them 2:1 to cache pages as per
the seeks setting. This is a huge waste of memory.
These workloads also deal with tens of thousands of open files and use
/proc for introspection, which ends up growing the proc_inode_cache to
absurdly large sizes - again at the cost of valuable cache space, which
isn't a reasonable trade-off, given that proc inodes can be re-created
without involving the disk.
This patch implements a "zero-seek" setting for shrinkers that results in
a target ratio of 0:1 between their objects and IO-backed caches. This
allows such virtual caches to grow when memory is available (they do
cache/avoid CPU work after all), but effectively disables them as soon as
IO-backed objects are under pressure.
It then switches the shrinkers for procfs and sysfs metadata, as well as
excess page cache shadow nodes, to the new zero-seek setting.
Link: http://lkml.kernel.org/r/20181009184732.762-5-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reported-by: Domas Mituzas <dmituzas@fb.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Rik van Riel <riel@surriel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When systems are overcommitted and resources become contended, it's hard
to tell exactly the impact this has on workload productivity, or how close
the system is to lockups and OOM kills. In particular, when machines work
multiple jobs concurrently, the impact of overcommit in terms of latency
and throughput on the individual job can be enormous.
In order to maximize hardware utilization without sacrificing individual
job health or risk complete machine lockups, this patch implements a way
to quantify resource pressure in the system.
A kernel built with CONFIG_PSI=y creates files in /proc/pressure/ that
expose the percentage of time the system is stalled on CPU, memory, or IO,
respectively. Stall states are aggregate versions of the per-task delay
accounting delays:
cpu: some tasks are runnable but not executing on a CPU
memory: tasks are reclaiming, or waiting for swapin or thrashing cache
io: tasks are waiting for io completions
These percentages of walltime can be thought of as pressure percentages,
and they give a general sense of system health and productivity loss
incurred by resource overcommit. They can also indicate when the system
is approaching lockup scenarios and OOMs.
To do this, psi keeps track of the task states associated with each CPU
and samples the time they spend in stall states. Every 2 seconds, the
samples are averaged across CPUs - weighted by the CPUs' non-idle time to
eliminate artifacts from unused CPUs - and translated into percentages of
walltime. A running average of those percentages is maintained over 10s,
1m, and 5m periods (similar to the loadaverage).
[hannes@cmpxchg.org: doc fixlet, per Randy]
Link: http://lkml.kernel.org/r/20180828205625.GA14030@cmpxchg.org
[hannes@cmpxchg.org: code optimization]
Link: http://lkml.kernel.org/r/20180907175015.GA8479@cmpxchg.org
[hannes@cmpxchg.org: rename psi_clock() to psi_update_work(), per Peter]
Link: http://lkml.kernel.org/r/20180907145404.GB11088@cmpxchg.org
[hannes@cmpxchg.org: fix build]
Link: http://lkml.kernel.org/r/20180913014222.GA2370@cmpxchg.org
Link: http://lkml.kernel.org/r/20180828172258.3185-9-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Daniel Drake <drake@endlessm.com>
Tested-by: Suren Baghdasaryan <surenb@google.com>
Cc: Christopher Lameter <cl@linux.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Weiner <jweiner@fb.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Enderborg <peter.enderborg@sony.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vinayak Menon <vinmenon@codeaurora.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Refaults happen during transitions between workingsets as well as in-place
thrashing. Knowing the difference between the two has a range of
applications, including measuring the impact of memory shortage on the
system performance, as well as the ability to smarter balance pressure
between the filesystem cache and the swap-backed workingset.
During workingset transitions, inactive cache refaults and pushes out
established active cache. When that active cache isn't stale, however,
and also ends up refaulting, that's bonafide thrashing.
Introduce a new page flag that tells on eviction whether the page has been
active or not in its lifetime. This bit is then stored in the shadow
entry, to classify refaults as transitioning or thrashing.
How many page->flags does this leave us with on 32-bit?
20 bits are always page flags
21 if you have an MMU
23 with the zone bits for DMA, Normal, HighMem, Movable
29 with the sparsemem section bits
30 if PAE is enabled
31 with this patch.
So on 32-bit PAE, that leaves 1 bit for distinguishing two NUMA nodes. If
that's not enough, the system can switch to discontigmem and re-gain the 6
or 7 sparsemem section bits.
Link: http://lkml.kernel.org/r/20180828172258.3185-3-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Daniel Drake <drake@endlessm.com>
Tested-by: Suren Baghdasaryan <surenb@google.com>
Cc: Christopher Lameter <cl@linux.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Weiner <jweiner@fb.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Enderborg <peter.enderborg@sony.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vinayak Menon <vinmenon@codeaurora.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
I've noticed, that dying memory cgroups are often pinned in memory by a
single pagecache page. Even under moderate memory pressure they sometimes
stayed in such state for a long time. That looked strange.
My investigation showed that the problem is caused by applying the LRU
pressure balancing math:
scan = div64_u64(scan * fraction[lru], denominator),
where
denominator = fraction[anon] + fraction[file] + 1.
Because fraction[lru] is always less than denominator, if the initial scan
size is 1, the result is always 0.
This means the last page is not scanned and has
no chances to be reclaimed.
Fix this by rounding up the result of the division.
In practice this change significantly improves the speed of dying cgroups
reclaim.
[guro@fb.com: prevent double calculation of DIV64_U64_ROUND_UP() arguments]
Link: http://lkml.kernel.org/r/20180829213311.GA13501@castle
Link: http://lkml.kernel.org/r/20180827162621.30187-3-guro@fb.com
Signed-off-by: Roman Gushchin <guro@fb.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Both callers of __delete_from_swap_cache have the swp_entry_t already,
so pass that in to make constructing the XA_STATE easier.
Signed-off-by: Matthew Wilcox <willy@infradead.org>
do_shrink_slab() returns unsigned long value, and the placing into int
variable cuts high bytes off. Then we compare ret and 0xfffffffe (since
SHRINK_EMPTY is converted to ret type).
Thus a large number of objects returned by do_shrink_slab() may be
interpreted as SHRINK_EMPTY, if low bytes of their value are equal to
0xfffffffe. Fix that by declaration ret as unsigned long in these
functions.
Link: http://lkml.kernel.org/r/153813407177.17544.14888305435570723973.stgit@localhost.localdomain
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Reported-by: Cyrill Gorcunov <gorcunov@openvz.org>
Acked-by: Cyrill Gorcunov <gorcunov@openvz.org>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Shakeel Butt <shakeelb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
9092c71bb7 ("mm: use sc->priority for slab shrink targets") changed the
way that the target slab pressure is calculated and made it
priority-based:
delta = freeable >> priority;
delta *= 4;
do_div(delta, shrinker->seeks);
The problem is that on a default priority (which is 12) no pressure is
applied at all, if the number of potentially reclaimable objects is less
than 4096 (1<<12).
This causes the last objects on slab caches of no longer used cgroups to
(almost) never get reclaimed. It's obviously a waste of memory.
It can be especially painful, if these stale objects are holding a
reference to a dying cgroup. Slab LRU lists are reparented on memcg
offlining, but corresponding objects are still holding a reference to the
dying cgroup. If we don't scan these objects, the dying cgroup can't go
away. Most likely, the parent cgroup hasn't any directly charged objects,
only remaining objects from dying children cgroups. So it can easily hold
a reference to hundreds of dying cgroups.
If there are no big spikes in memory pressure, and new memory cgroups are
created and destroyed periodically, this causes the number of dying
cgroups grow steadily, causing a slow-ish and hard-to-detect memory
"leak". It's not a real leak, as the memory can be eventually reclaimed,
but it could not happen in a real life at all. I've seen hosts with a
steadily climbing number of dying cgroups, which doesn't show any signs of
a decline in months, despite the host is loaded with a production
workload.
It is an obvious waste of memory, and to prevent it, let's apply a minimal
pressure even on small shrinker lists. E.g. if there are freeable
objects, let's scan at least min(freeable, scan_batch) objects.
This fix significantly improves a chance of a dying cgroup to be
reclaimed, and together with some previous patches stops the steady growth
of the dying cgroups number on some of our hosts.
Link: http://lkml.kernel.org/r/20180905230759.12236-1-guro@fb.com
Fixes: 9092c71bb7 ("mm: use sc->priority for slab shrink targets")
Signed-off-by: Roman Gushchin <guro@fb.com>
Acked-by: Rik van Riel <riel@surriel.com>
Cc: Josef Bacik <jbacik@fb.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
page_freeze_refs/page_unfreeze_refs have already been relplaced by
page_ref_freeze/page_ref_unfreeze , but they are not modified in the
comments.
Link: http://lkml.kernel.org/r/1532590226-106038-1-git-send-email-jiang.biao2@zte.com.cn
Signed-off-by: Jiang Biao <jiang.biao2@zte.com.cn>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There is a sad BUG introduced in patch adding SHRINKER_REGISTERING.
shrinker_idr business is only for memcg-aware shrinkers. Only such type
of shrinkers have id and they must be finaly installed via idr_replace()
in this function. For !memcg-aware shrinkers we never initialize
shrinker->id field.
But there are all types of shrinkers passed to idr_replace(), and every
!memcg-aware shrinker with random ID (most probably, its id is 0)
replaces memcg-aware shrinker pointed by the ID in IDR.
This patch fixes the problem.
Link: http://lkml.kernel.org/r/8ff8a793-8211-713a-4ed9-d6e52390c2fc@virtuozzo.com
Fixes: 7e010df53c "mm: use special value SHRINKER_REGISTERING instead of list_empty() check"
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Reported-by: <syzbot+d5f648a1bfe15678786b@syzkaller.appspotmail.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Josef Bacik <jbacik@fb.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: <syzkaller-bugs@googlegroups.com>
Cc: Huang Ying <ying.huang@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The patch introduces a special value SHRINKER_REGISTERING to use instead
of list_empty() to differ a registering shrinker from unregistered
shrinker. Why we need that at all?
Shrinker registration is split in two parts. The first one is
prealloc_shrinker(), which allocates shrinker memory and reserves ID in
shrinker_idr. This function can fail. The second is
register_shrinker_prepared(), and it finalizes the registration. This
function actually makes shrinker available to be used from
shrink_slab(), and it can't fail.
One shrinker may be based on more then one LRU lists. So, we never
clear the bit in memcg shrinker maps, when (one of) corresponding LRU
list becomes empty, since other LRU lists may be not empty. See
superblock shrinker for example: it is based on two LRU lists:
s_inode_lru and s_dentry_lru. We do not want to clear shrinker bit,
when there are no inodes in s_inode_lru, as s_dentry_lru may contain
dentries.
Instead of that, we use special algorithm to detect shrinkers having no
elements at all its LRU lists, and this is made in shrink_slab_memcg().
See the comment in this function for the details.
Also, in shrink_slab_memcg() we clear shrinker bit in the map, when we
meet unregistered shrinker (bit is set, while there is no a shrinker in
IDR). Otherwise, we would have done that at the moment of shrinker
unregistration for all memcgs (and this looks worse, since iteration
over all memcg may take much time). Also this would have imposed
restrictions on shrinker unregistration order for its users: they would
have had to guarantee, there are no new elements after
unregister_shrinker() (otherwise, a new added element would have set a
bit).
So, if we meet a set bit in map and no shrinker in IDR when we're
iterating over the map in shrink_slab_memcg(), this means the
corresponding shrinker is unregistered, and we must clear the bit.
Another case is shrinker registration. We want two things there:
1) do_shrink_slab() can be called only for completely registered
shrinkers;
2) shrinker internal lists may be populated in any order with
register_shrinker_prepared() (let's talk on the example with sb). Both
of:
a)list_lru_add(&inode->i_sb->s_inode_lru, &inode->i_lru); [cpu0]
memcg_set_shrinker_bit(); [cpu0]
...
register_shrinker_prepared(); [cpu1]
and
b)register_shrinker_prepared(); [cpu0]
...
list_lru_add(&inode->i_sb->s_inode_lru, &inode->i_lru); [cpu1]
memcg_set_shrinker_bit(); [cpu1]
are legitimate. We don't want to impose restriction here and to
force people to use only (b) variant. We don't want to force people to
care, there is no elements in LRU lists before the shrinker is
completely registered. Internal users of LRU lists and shrinker code
are two different subsystems, and they have to be closed in themselves
each other.
In (a) case we have the bit set before shrinker is completely
registered. We don't want do_shrink_slab() is called at this moment, so
we have to detect such the registering shrinkers.
Before this patch list_empty() (shrinker is not linked to the list)
check was used for that. So, in (a) there could be a bit set, but we
don't call do_shrink_slab() unless shrinker is linked to the list. It's
just an indicator, I just overloaded linking to the list.
This was not the best solution, since it's better not to touch the
shrinker memory from shrink_slab_memcg() before it's completely
registered (this also will be useful in the future to make shrink_slab()
completely lockless).
So, this patch introduces better way to detect registering shrinker,
which allows not to dereference shrinker memory. It's just a ~0UL
value, which we insert into the IDR during ID allocation. After
shrinker is ready to be used, we insert actual shrinker pointer in the
IDR, and it becomes available to shrink_slab_memcg().
We can't use NULL instead of this new value for this purpose as:
shrink_slab_memcg() already uses NULL to detect unregistered shrinkers,
and we don't want the function sees NULL and clears the bit, otherwise
(a) won't work.
This is the only thing the patch makes: the better way to detect
registering shrinker. Nothing else this patch makes.
Also this gives a better assembler, but it's minor side of the patch:
Before:
callq <idr_find>
mov %rax,%r15
test %rax,%rax
je <shrink_slab_memcg+0x1d5>
mov 0x20(%rax),%rax
lea 0x20(%r15),%rdx
cmp %rax,%rdx
je <shrink_slab_memcg+0xbd>
mov 0x8(%rsp),%edx
mov %r15,%rsi
lea 0x10(%rsp),%rdi
callq <do_shrink_slab>
After:
callq <idr_find>
mov %rax,%r15
lea -0x1(%rax),%rax
cmp $0xfffffffffffffffd,%rax
ja <shrink_slab_memcg+0x1cd>
mov 0x8(%rsp),%edx
mov %r15,%rsi
lea 0x10(%rsp),%rdi
callq ffffffff810cefd0 <do_shrink_slab>
[ktkhai@virtuozzo.com: add #ifdef CONFIG_MEMCG_KMEM around idr_replace()]
Link: http://lkml.kernel.org/r/758b8fec-7573-47eb-b26a-7b2847ae7b8c@virtuozzo.com
Link: http://lkml.kernel.org/r/153355467546.11522.4518015068123480218.stgit@localhost.localdomain
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Josef Bacik <jbacik@fb.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In case of shrink_slab_memcg() we do not zero nid, when shrinker is not
numa-aware. This is not a real problem, since currently all memcg-aware
shrinkers are numa-aware too (we have two: super_block shrinker and
workingset shrinker), but something may change in the future.
Link: http://lkml.kernel.org/r/153320759911.18959.8842396230157677671.stgit@localhost.localdomain
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Josef Bacik <jbacik@fb.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
To avoid further unneed calls of do_shrink_slab() for shrinkers, which
already do not have any charged objects in a memcg, their bits have to
be cleared.
This patch introduces a lockless mechanism to do that without races
without parallel list lru add. After do_shrink_slab() returns
SHRINK_EMPTY the first time, we clear the bit and call it once again.
Then we restore the bit, if the new return value is different.
Note, that single smp_mb__after_atomic() in shrink_slab_memcg() covers
two situations:
1)list_lru_add() shrink_slab_memcg
list_add_tail() for_each_set_bit() <--- read bit
do_shrink_slab() <--- missed list update (no barrier)
<MB> <MB>
set_bit() do_shrink_slab() <--- seen list update
This situation, when the first do_shrink_slab() sees set bit, but it
doesn't see list update (i.e., race with the first element queueing), is
rare. So we don't add <MB> before the first call of do_shrink_slab()
instead of this to do not slow down generic case. Also, it's need the
second call as seen in below in (2).
2)list_lru_add() shrink_slab_memcg()
list_add_tail() ...
set_bit() ...
... for_each_set_bit()
do_shrink_slab() do_shrink_slab()
clear_bit() ...
... ...
list_lru_add() ...
list_add_tail() clear_bit()
<MB> <MB>
set_bit() do_shrink_slab()
The barriers guarantee that the second do_shrink_slab() in the right
side task sees list update if really cleared the bit. This case is
drawn in the code comment.
[Results/performance of the patchset]
After the whole patchset applied the below test shows signify increase
of performance:
$echo 1 > /sys/fs/cgroup/memory/memory.use_hierarchy
$mkdir /sys/fs/cgroup/memory/ct
$echo 4000M > /sys/fs/cgroup/memory/ct/memory.kmem.limit_in_bytes
$for i in `seq 0 4000`; do mkdir /sys/fs/cgroup/memory/ct/$i;
echo $$ > /sys/fs/cgroup/memory/ct/$i/cgroup.procs;
mkdir -p s/$i; mount -t tmpfs $i s/$i;
touch s/$i/file; done
Then, 5 sequential calls of drop caches:
$time echo 3 > /proc/sys/vm/drop_caches
1)Before:
0.00user 13.78system 0:13.78elapsed 99%CPU
0.00user 5.59system 0:05.60elapsed 99%CPU
0.00user 5.48system 0:05.48elapsed 99%CPU
0.00user 8.35system 0:08.35elapsed 99%CPU
0.00user 8.34system 0:08.35elapsed 99%CPU
2)After
0.00user 1.10system 0:01.10elapsed 99%CPU
0.00user 0.00system 0:00.01elapsed 64%CPU
0.00user 0.01system 0:00.01elapsed 82%CPU
0.00user 0.00system 0:00.01elapsed 64%CPU
0.00user 0.01system 0:00.01elapsed 82%CPU
The results show the performance increases at least in 548 times.
Shakeel Butt tested this patchset with fork-bomb on his configuration:
> I created 255 memcgs, 255 ext4 mounts and made each memcg create a
> file containing few KiBs on corresponding mount. Then in a separate
> memcg of 200 MiB limit ran a fork-bomb.
>
> I ran the "perf record -ag -- sleep 60" and below are the results:
>
> Without the patch series:
> Samples: 4M of event 'cycles', Event count (approx.): 3279403076005
> + 36.40% fb.sh [kernel.kallsyms] [k] shrink_slab
> + 18.97% fb.sh [kernel.kallsyms] [k] list_lru_count_one
> + 6.75% fb.sh [kernel.kallsyms] [k] super_cache_count
> + 0.49% fb.sh [kernel.kallsyms] [k] down_read_trylock
> + 0.44% fb.sh [kernel.kallsyms] [k] mem_cgroup_iter
> + 0.27% fb.sh [kernel.kallsyms] [k] up_read
> + 0.21% fb.sh [kernel.kallsyms] [k] osq_lock
> + 0.13% fb.sh [kernel.kallsyms] [k] shmem_unused_huge_count
> + 0.08% fb.sh [kernel.kallsyms] [k] shrink_node_memcg
> + 0.08% fb.sh [kernel.kallsyms] [k] shrink_node
>
> With the patch series:
> Samples: 4M of event 'cycles', Event count (approx.): 2756866824946
> + 47.49% fb.sh [kernel.kallsyms] [k] down_read_trylock
> + 30.72% fb.sh [kernel.kallsyms] [k] up_read
> + 9.51% fb.sh [kernel.kallsyms] [k] mem_cgroup_iter
> + 1.69% fb.sh [kernel.kallsyms] [k] shrink_node_memcg
> + 1.35% fb.sh [kernel.kallsyms] [k] mem_cgroup_protected
> + 1.05% fb.sh [kernel.kallsyms] [k] queued_spin_lock_slowpath
> + 0.85% fb.sh [kernel.kallsyms] [k] _raw_spin_lock
> + 0.78% fb.sh [kernel.kallsyms] [k] lruvec_lru_size
> + 0.57% fb.sh [kernel.kallsyms] [k] shrink_node
> + 0.54% fb.sh [kernel.kallsyms] [k] queue_work_on
> + 0.46% fb.sh [kernel.kallsyms] [k] shrink_slab_memcg
[ktkhai@virtuozzo.com: v9]
Link: http://lkml.kernel.org/r/153112561772.4097.11011071937553113003.stgit@localhost.localdomain
Link: http://lkml.kernel.org/r/153063070859.1818.11870882950920963480.stgit@localhost.localdomain
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Tested-by: Shakeel Butt <shakeelb@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Josef Bacik <jbacik@fb.com>
Cc: Li RongQing <lirongqing@baidu.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matthias Kaehlcke <mka@chromium.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Sahitya Tummala <stummala@codeaurora.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <longman@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We need to distinguish the situations when shrinker has very small
amount of objects (see vfs_pressure_ratio() called from
super_cache_count()), and when it has no objects at all. Currently, in
the both of these cases, shrinker::count_objects() returns 0.
The patch introduces new SHRINK_EMPTY return value, which will be used
for "no objects at all" case. It's is a refactoring mostly, as
SHRINK_EMPTY is replaced by 0 by all callers of do_shrink_slab() in this
patch, and all the magic will happen in further.
Link: http://lkml.kernel.org/r/153063069574.1818.11037751256699341813.stgit@localhost.localdomain
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Tested-by: Shakeel Butt <shakeelb@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Josef Bacik <jbacik@fb.com>
Cc: Li RongQing <lirongqing@baidu.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matthias Kaehlcke <mka@chromium.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Sahitya Tummala <stummala@codeaurora.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <longman@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
