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linux/mm
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Linus Torvalds 00a3d660cb Revert "fs: do not prefault sys_write() user buffer pages" 
This reverts commit 998ef75ddb.

The commit itself does not appear to be buggy per se, but it is exposing
a bug in ext4 (and Ted thinks ext3 too, but we solved that by getting
rid of it).  It's too late in the release cycle to really worry about
this, even if Dave Hansen has a patch that may actually fix the
underlying ext4 problem.  We can (and should) revisit this for the next
release.

The problem is that moving the prefaulting later now exposes a special
case with partially successful writes that isn't handled correctly.  And
the prefaulting likely isn't normally even that much of a performance
issue - it looks like at least one reason Dave saw this in his
performance tests is that he also ran them on Skylake that now supports
the new SMAP code, which makes the normally very cheap user space
prefaulting noticeably more expensive.

Bisected-and-acked-by: Ted Ts'o <tytso@mit.edu>
Analyzed-and-acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-10-07 08:32:38 +01:00
..
kasan kasan: fix last shadow judgement in memory_is_poisoned_16() 2015-09-17 21:16:07 -07:00
backing-dev.c Merge branch 'for-4.3/blkcg' of git://git.kernel.dk/linux-block 2015-09-10 18:56:14 -07:00
balloon_compaction.c
bootmem.c bootmem: avoid freeing to bootmem after bootmem is done 2015-09-08 15:35:28 -07:00
cleancache.c
cma.c
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/compaction: correct to flush migrated pages if pageblock skip happens 2015-09-08 15:35:28 -07:00
debug-pagealloc.c
debug.c mm: introduce idle page tracking 2015-09-10 13:29:01 -07:00
dmapool.c dmapool: fix overflow condition in pool_find_page() 2015-10-01 21:42:35 -04:00
early_ioremap.c mm/early_ioremap: add explicit #include of asm/early_ioremap.h 2015-09-11 15:21:34 -07:00
fadvise.c
failslab.c
filemap.c Revert "fs: do not prefault sys_write() user buffer pages" 2015-10-07 08:32:38 +01:00
frame_vector.c [media] mm: Provide new get_vaddr_frames() helper 2015-08-16 13:02:47 -03:00
frontswap.c
gup.c mm: make GUP handle pfn mapping unless FOLL_GET is requested 2015-09-04 16:54:41 -07:00
highmem.c
huge_memory.c mm: introduce idle page tracking 2015-09-10 13:29:01 -07:00
hugetlb.c mm: hugetlbfs: skip shared VMAs when unmapping private pages to satisfy a fault 2015-10-01 21:42:35 -04:00
hugetlb_cgroup.c
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/compaction: correct to flush migrated pages if pageblock skip happens 2015-09-08 15:35:28 -07:00
interval_tree.c
Kconfig media updates for v4.3-rc1 2015-09-11 16:42:39 -07:00
Kconfig.debug
kmemcheck.c
kmemleak-test.c
kmemleak.c kmemleak: use seq_hex_dump() to dump buffers 2015-09-10 13:29:01 -07:00
ksm.c
list_lru.c list_lru: don't call list_lru_from_kmem if the list_head is empty 2015-09-08 15:35:28 -07:00
maccess.c lib: move strncpy_from_unsafe() into mm/maccess.c 2015-08-31 12:36:10 -07:00
madvise.c mm: madvise allow remove operation for hugetlbfs 2015-09-08 15:35:28 -07:00
Makefile media updates for v4.3-rc1 2015-09-11 16:42:39 -07:00
memblock.c mm/memblock.c: fix comment in __next_mem_range() 2015-09-08 15:35:28 -07:00
memcontrol.c memcg: remove pcp_counter_lock 2015-10-01 21:42:35 -04:00
memory-failure.c hwpoison: use page_cgroup_ino for filtering by memcg 2015-09-10 13:29:01 -07:00
memory.c mm: use vma_is_anonymous() in create_huge_pmd() and wp_huge_pmd() 2015-09-10 13:29:01 -07:00
memory_hotplug.c libnvdimm for 4.3: 2015-09-08 14:35:59 -07:00
mempolicy.c mm: rename alloc_pages_exact_node() to __alloc_pages_node() 2015-09-08 15:35:28 -07:00
mempool.c mm/mempool: allow NULL `pool' pointer in mempool_destroy() 2015-09-08 15:35:28 -07:00
memtest.c memtest: remove unused header files 2015-09-08 15:35:28 -07:00
migrate.c memcg: fix dirty page migration 2015-10-01 21:42:35 -04:00
mincore.c
mlock.c userfaultfd: teach vma_merge to merge across vma->vm_userfaultfd_ctx 2015-09-04 16:54:41 -07:00
mm_init.c mm: meminit: remove mminit_verify_page_links 2015-06-30 19:44:56 -07:00
mmap.c mm, dax: VMA with vm_ops->pfn_mkwrite wants to be write-notified 2015-09-22 15:09:53 -07:00
mmu_context.c
mmu_notifier.c mmu-notifier: add clear_young callback 2015-09-10 13:29:01 -07:00
mmzone.c
mprotect.c userfaultfd: teach vma_merge to merge across vma->vm_userfaultfd_ctx 2015-09-04 16:54:41 -07:00
mremap.c mremap: simplify the "overlap" check in mremap_to() 2015-09-04 16:54:41 -07:00
msync.c
nobootmem.c mm: page_alloc: pass PFN to __free_pages_bootmem 2015-06-30 19:44:55 -07:00
nommu.c mm, mpx: add "vm_flags_t vm_flags" arg to do_mmap_pgoff() 2015-09-10 13:29:01 -07:00
oom_kill.c mm, oom: remove unnecessary variable 2015-09-08 15:35:28 -07:00
page-writeback.c Merge branch 'for-4.3/blkcg' of git://git.kernel.dk/linux-block 2015-09-10 18:56:14 -07:00
page_alloc.c Merge branch 'akpm' (patches from Andrew) 2015-09-08 17:52:23 -07:00
page_counter.c
page_ext.c mm: introduce idle page tracking 2015-09-10 13:29:01 -07:00
page_idle.c mm: introduce idle page tracking 2015-09-10 13:29:01 -07:00
page_io.c fs: use helper bio_add_page() instead of open coding on bi_io_vec 2015-08-13 12:32:00 -06:00
page_isolation.c mm, page_isolation: make set/unset_migratetype_isolate() file-local 2015-09-08 15:35:28 -07:00
page_owner.c mm/page_owner: set correct gfp_mask on page_owner 2015-07-17 16:39:54 -07:00
pagewalk.c
percpu-km.c
percpu-vm.c
percpu.c percpu: clean up of schunk->map[] assignment in pcpu_setup_first_chunk 2015-07-21 11:31:00 -04:00
pgtable-generic.c
process_vm_access.c
quicklist.c
readahead.c
rmap.c mm: introduce idle page tracking 2015-09-10 13:29:01 -07:00
shmem.c shmem: recalculate file inode when fstat 2015-09-08 15:35:28 -07:00
slab.c mm/slab: fix unexpected index mapping result of kmalloc_size(INDEX_NODE+1) 2015-10-01 21:42:35 -04:00
slab.h mm/slab.h: fix argument order in cache_from_obj's error message 2015-09-04 16:54:41 -07:00
slab_common.c memcg: export struct mem_cgroup 2015-09-08 15:35:28 -07:00
slob.c mm: rename alloc_pages_exact_node() to __alloc_pages_node() 2015-09-08 15:35:28 -07:00
slub.c mm: rename alloc_pages_exact_node() to __alloc_pages_node() 2015-09-08 15:35:28 -07:00
sparse-vmemmap.c
sparse.c
swap.c mm: introduce idle page tracking 2015-09-10 13:29:01 -07:00
swap_cgroup.c
swap_state.c mm: swap: zswap: maybe_preload & refactoring 2015-09-08 15:35:28 -07:00
swapfile.c mm: /proc/pid/smaps:: show proportional swap share of the mapping 2015-09-08 15:35:28 -07:00
truncate.c
userfaultfd.c userfaultfd: avoid mmap_sem read recursion in mcopy_atomic 2015-09-04 16:54:41 -07:00
util.c
vmacache.c
vmalloc.c
vmpressure.c
vmscan.c vmscan: fix sane_reclaim helper for legacy memcg 2015-09-22 15:09:53 -07:00
vmstat.c
workingset.c
zbud.c mm: zbud: constify the zbud_ops 2015-09-08 15:35:28 -07:00
zpool.c zpool: add zpool_has_pool() 2015-09-10 13:29:01 -07:00
zsmalloc.c mm: zpool: constify the zpool_ops 2015-09-08 15:35:28 -07:00
zswap.c zswap: change zpool/compressor at runtime 2015-09-10 13:29:01 -07:00