linux/mm
Hugh Dickins 684283988f huge pagecache: mmap_sem is unlocked when truncation splits pmd
zap_pmd_range()'s CONFIG_DEBUG_VM !rwsem_is_locked(&mmap_sem) BUG() will
be invalid with huge pagecache, in whatever way it is implemented:
truncation of a hugely-mapped file to an unhugely-aligned size would
easily hit it.

(Although anon THP could in principle apply khugepaged to private file
mappings, which are not excluded by the MADV_HUGEPAGE restrictions, in
practice there's a vm_ops check which excludes them, so it never hits
this BUG() - there's no interface to "truncate" an anonymous mapping.)

We could complicate the test, to check i_mmap_rwsem also when there's a
vm_file; but my inclination was to make zap_pmd_range() more readable by
simply deleting this check.  A search has shown no report of the issue
in the years since commit e0897d75f0 ("mm, thp: print useful
information when mmap_sem is unlocked in zap_pmd_range") expanded it
from VM_BUG_ON() - though I cannot point to what commit I would say then
fixed the issue.

But there are a couple of other patches now floating around, neither yet
in the tree: let's agree to retain the check as a VM_BUG_ON_VMA(), as
Matthew Wilcox has done; but subject to a vma_is_anonymous() check, as
Kirill Shutemov has done.  And let's get this in, without waiting for
any particular huge pagecache implementation to reach the tree.

Matthew said "We can reproduce this BUG() in the current Linus tree with
DAX PMDs".

Signed-off-by: Hugh Dickins <hughd@google.com>
Tested-by: Matthew Wilcox <willy@linux.intel.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andres Lagar-Cavilla <andreslc@google.com>
Cc: Yang Shi <yang.shi@linaro.org>
Cc: Ning Qu <quning@gmail.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Andres Lagar-Cavilla <andreslc@google.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-05-05 17:38:53 -07:00
..
kasan mm, kasan: fix compilation for CONFIG_SLAB 2016-04-01 17:03:37 -05:00
backing-dev.c writeback: fix the wrong congested state variable definition 2016-03-31 12:26:25 -06:00
balloon_compaction.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2016-03-17 21:38:27 -07:00
bootmem.c mm: convert printk(KERN_<LEVEL> to pr_<level> 2016-03-17 15:09:34 -07:00
cleancache.c cleancache: constify cleancache_ops structure 2016-01-27 09:09:57 -05:00
cma.c mm/cma.c: suppress warning 2015-11-05 19:34:48 -08:00
cma.h mm: cma: mark cma_bitmap_maxno() inline in header 2015-08-14 15:56:32 -07:00
cma_debug.c mm/cma_debug: correct size input to bitmap function 2015-07-17 16:39:54 -07:00
compaction.c mm, kswapd: replace kswapd compaction with waking up kcompactd 2016-03-17 15:09:34 -07:00
debug.c mm: introduce page reference manipulation functions 2016-03-17 15:09:34 -07:00
debug_page_ref.c mm/page_ref: add tracepoint to track down page reference manipulation 2016-03-17 15:09:34 -07:00
dmapool.c mm: convert printk(KERN_<LEVEL> to pr_<level> 2016-03-17 15:09:34 -07:00
early_ioremap.c mm/early_ioremap: use offset_in_page macro 2015-11-05 19:34:48 -08:00
fadvise.c mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros 2016-04-04 10:41:08 -07:00
failslab.c mm: fault-inject take over bootstrap kmem_cache check 2016-03-15 16:55:16 -07:00
filemap.c mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros 2016-04-04 10:41:08 -07:00
frame_vector.c mm/gup: Switch all callers of get_user_pages() to not pass tsk/mm 2016-02-16 10:11:12 +01:00
frontswap.c frontswap: allow multiple backends 2015-06-24 17:49:45 -07:00
gup.c Merge branch 'mm-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-04-14 19:31:34 -07:00
highmem.c
huge_memory.c mm: thp: correct split_huge_pages file permission 2016-05-05 17:38:53 -07:00
hugetlb.c mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros 2016-04-04 10:41:08 -07:00
hugetlb_cgroup.c mm: make compound_head() robust 2015-11-06 17:50:42 -08:00
hwpoison-inject.c hwpoison: use page_cgroup_ino for filtering by memcg 2015-09-10 13:29:01 -07:00
init-mm.c
internal.h mm, oom: introduce oom reaper 2016-03-25 16:37:42 -07:00
interval_tree.c mm: replace vma->sharead.linear with vma->shared 2015-02-10 14:30:31 -08:00
Kconfig Merge branch 'mm-pkeys-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-03-20 19:08:56 -07:00
Kconfig.debug mm/page_ref: add tracepoint to track down page reference manipulation 2016-03-17 15:09:34 -07:00
kmemcheck.c mm: convert printk(KERN_<LEVEL> to pr_<level> 2016-03-17 15:09:34 -07:00
kmemleak-test.c mm: convert printk(KERN_<LEVEL> to pr_<level> 2016-03-17 15:09:34 -07:00
kmemleak.c mm: coalesce split strings 2016-03-17 15:09:34 -07:00
ksm.c mm/core: Do not enforce PKEY permissions on remote mm access 2016-02-18 19:46:28 +01:00
list_lru.c mm: memcontrol: move kmem accounting code to CONFIG_MEMCG 2016-01-20 17:09:18 -08:00
maccess.c mm/maccess.c: actually return -EFAULT from strncpy_from_unsafe 2015-11-05 19:34:48 -08:00
madvise.c mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros 2016-04-04 10:41:08 -07:00
Makefile mm, kasan: SLAB support 2016-03-25 16:37:42 -07:00
memblock.c mm: coalesce split strings 2016-03-17 15:09:34 -07:00
memcontrol.c memcg: relocate charge moving from ->attach to ->post_attach 2016-04-25 15:45:14 -04:00
memory-failure.c mm/memory-failure: fix race with compound page split/merge 2016-04-28 19:34:04 -07:00
memory.c huge pagecache: mmap_sem is unlocked when truncation splits pmd 2016-05-05 17:38:53 -07:00
memory_hotplug.c mm: coalesce split strings 2016-03-17 15:09:34 -07:00
mempolicy.c Merge branch 'mm-pkeys-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-03-20 19:08:56 -07:00
mempool.c mm, kasan: add GFP flags to KASAN API 2016-03-25 16:37:42 -07:00
memtest.c memtest: remove unused header files 2015-09-08 15:35:28 -07:00
migrate.c mm/hwpoison: fix wrong num_poisoned_pages accounting 2016-04-28 19:34:04 -07:00
mincore.c mm, fs: remove remaining PAGE_CACHE_* and page_cache_{get,release} usage 2016-04-04 10:41:08 -07:00
mlock.c mm: fix mlock accouting 2016-01-21 17:20:51 -08:00
mm_init.c mm: convert printk(KERN_<LEVEL> to pr_<level> 2016-03-17 15:09:34 -07:00
mmap.c Merge branch 'mm-pkeys-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-03-20 19:08:56 -07:00
mmu_context.c
mmu_notifier.c fix Christoph's email addresses 2016-03-17 15:09:34 -07:00
mmzone.c mm/mmzone.c: memmap_valid_within() can be boolean 2016-01-14 16:00:49 -08:00
mprotect.c mm/mprotect.c: don't imply PROT_EXEC on non-exec fs 2016-03-22 15:36:02 -07:00
mremap.c mm: cleanup *pte_alloc* interfaces 2016-03-17 15:09:34 -07:00
msync.c mm/msync: use offset_in_page macro 2015-11-05 19:34:48 -08:00
nobootmem.c mm: convert printk(KERN_<LEVEL> to pr_<level> 2016-03-17 15:09:34 -07:00
nommu.c Merge branch 'mm-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-04-14 19:31:34 -07:00
oom_kill.c oom, oom_reaper: do not enqueue task if it is on the oom_reaper_list head 2016-04-01 17:03:37 -05:00
page-writeback.c mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros 2016-04-04 10:41:08 -07:00
page_alloc.c mm/page_alloc: prevent merging between isolated and other pageblocks 2016-03-25 16:37:42 -07:00
page_counter.c mm: page_counter: let page_counter_try_charge() return bool 2015-11-05 19:34:48 -08:00
page_ext.c mm/page_poisoning.c: allow for zero poisoning 2016-03-15 16:55:16 -07:00
page_idle.c mm: add page_check_address_transhuge() helper 2016-01-15 17:56:32 -08:00
page_io.c mm: call swap_slot_free_notify() with page lock held 2016-04-28 19:34:04 -07:00
page_isolation.c mm/page_isolation.c: fix the function comments 2016-04-01 17:03:37 -05:00
page_owner.c mm: coalesce split strings 2016-03-17 15:09:34 -07:00
page_poison.c mm/page_poisoning.c: allow for zero poisoning 2016-03-15 16:55:16 -07:00
pagewalk.c thp: rename split_huge_page_pmd() to split_huge_pmd() 2016-01-15 17:56:32 -08:00
percpu-km.c mm: percpu: use pr_fmt to prefix output 2016-03-17 15:09:34 -07:00
percpu-vm.c
percpu.c mm: percpu: use pr_fmt to prefix output 2016-03-17 15:09:34 -07:00
pgtable-generic.c mm/thp/migration: switch from flush_tlb_range to flush_pmd_tlb_range 2016-03-17 15:09:34 -07:00
process_vm_access.c mm/gup: Introduce get_user_pages_remote() 2016-02-16 10:04:09 +01:00
quicklist.c fix Christoph's email addresses 2016-03-17 15:09:34 -07:00
readahead.c mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros 2016-04-04 10:41:08 -07:00
rmap.c Merge branch 'PAGE_CACHE_SIZE-removal' 2016-04-04 10:50:24 -07:00
shmem.c mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros 2016-04-04 10:41:08 -07:00
slab.c mm, kasan: add GFP flags to KASAN API 2016-03-25 16:37:42 -07:00
slab.h mm, kasan: add GFP flags to KASAN API 2016-03-25 16:37:42 -07:00
slab_common.c mm, kasan: add GFP flags to KASAN API 2016-03-25 16:37:42 -07:00
slob.c mm: slab: free kmem_cache_node after destroy sysfs file 2016-02-18 16:23:24 -08:00
slub.c mm, kasan: add GFP flags to KASAN API 2016-03-25 16:37:42 -07:00
sparse-vmemmap.c mm: convert printk(KERN_<LEVEL> to pr_<level> 2016-03-17 15:09:34 -07:00
sparse.c mm: convert printk(KERN_<LEVEL> to pr_<level> 2016-03-17 15:09:34 -07:00
swap.c thp: keep huge zero page pinned until tlb flush 2016-04-28 19:34:04 -07:00
swap_cgroup.c mm: convert printk(KERN_<LEVEL> to pr_<level> 2016-03-17 15:09:34 -07:00
swap_state.c mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros 2016-04-04 10:41:08 -07:00
swapfile.c mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros 2016-04-04 10:41:08 -07:00
truncate.c mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros 2016-04-04 10:41:08 -07:00
userfaultfd.c mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros 2016-04-04 10:41:08 -07:00
util.c Merge branch 'mm-pkeys-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-03-20 19:08:56 -07:00
vmacache.c mm/vmacache: inline vmacache_valid_mm() 2015-11-05 19:34:48 -08:00
vmalloc.c mm/vmalloc: use PAGE_ALIGNED() to check PAGE_SIZE alignment 2016-03-17 15:09:34 -07:00
vmpressure.c mm/vmpressure.c: fix subtree pressure detection 2016-02-03 08:28:43 -08:00
vmscan.c mm: wake kcompactd before kswapd's short sleep 2016-04-28 19:34:04 -07:00
vmstat.c thp, vmstats: count deferred split events 2016-03-17 15:09:34 -07:00
workingset.c mm: workingset: make shadow node shrinker memcg aware 2016-03-17 15:09:34 -07:00
zbud.c mm/zbud.c: use list_last_entry() instead of list_tail_entry() 2016-01-15 11:40:52 -08:00
zpool.c mm: zsmalloc: constify struct zs_pool name 2015-11-06 17:50:42 -08:00
zsmalloc.c mm/zsmalloc: add `freeable' column to pool stat 2016-03-17 15:09:34 -07:00
zswap.c mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros 2016-04-04 10:41:08 -07:00