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linux-stable/mm
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Andrea Arcangeli 1c641e8471 mm: thp: fix BUG on mm->nr_ptes 
Dave Jones reports a few Fedora users hitting the BUG_ON(mm->nr_ptes...)
in exit_mmap() recently.

Quoting Hugh's discovery and explanation of the SMP race condition:

  "mm->nr_ptes had unusual locking: down_read mmap_sem plus
   page_table_lock when incrementing, down_write mmap_sem (or mm_users
   0) when decrementing; whereas THP is careful to increment and
   decrement it under page_table_lock.

   Now most of those paths in THP also hold mmap_sem for read or write
   (with appropriate checks on mm_users), but two do not: when
   split_huge_page() is called by hwpoison_user_mappings(), and when
   called by add_to_swap().

   It's conceivable that the latter case is responsible for the
   exit_mmap() BUG_ON mm->nr_ptes that has been reported on Fedora."

The simplest way to fix it without having to alter the locking is to make
split_huge_page() a noop in nr_ptes terms, so by counting the preallocated
pagetables that exists for every mapped hugepage.  It was an arbitrary
choice not to count them and either way is not wrong or right, because
they are not used but they're still allocated.

Reported-by: Dave Jones <davej@redhat.com>
Reported-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Hugh Dickins <hughd@google.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Josh Boyer <jwboyer@redhat.com>
Cc: <stable@vger.kernel.org>	[3.0.x, 3.1.x, 3.2.x]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-05 15:49:43 -08:00
..
backing-dev.c backing-dev: fix wakeup timer races with bdi_unregister() 2012-02-01 16:52:49 +08:00
bootmem.c mm: bootmem: try harder to free pages in bulk 2012-01-10 16:30:45 -08:00
bounce.c Merge branch 'modsplit-Oct31_2011' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux 2011-11-06 19:44:47 -08:00
cleancache.c
compaction.c mm: compaction: check for overlapping nodes during isolation for migration 2012-02-08 19:03:51 -08:00
debug-pagealloc.c mm, x86: Remove debug_pagealloc_enabled 2011-12-06 09:24:07 +01:00
dmapool.c mm: fix implicit stat.h usage in dmapool.c 2011-10-31 09:20:12 -04:00
fadvise.c fadvise: only initiate writeback for specified range with FADV_DONTNEED 2012-01-10 16:30:43 -08:00
failslab.c switch debugfs to umode_t 2012-01-03 22:54:56 -05:00
filemap.c readahead: fix pipeline break caused by block plug 2012-02-03 16:16:41 -08:00
filemap_xip.c mm/filemap_xip.c: fix race condition in xip_file_fault() 2012-02-03 16:16:41 -08:00
fremap.c mm: delete various needless include <linux/module.h> 2011-10-31 09:20:11 -04:00
highmem.c Merge branch 'modsplit-Oct31_2011' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux 2011-11-06 19:44:47 -08:00
huge_memory.c mm: thp: fix BUG on mm->nr_ptes 2012-03-05 15:49:43 -08:00
hugetlb.c mm/hugetlb.c: undo change to page mapcount in fault handler 2012-01-23 08:38:48 -08:00
hwpoison-inject.c
init-mm.c atomic: use <linux/atomic.h> 2011-07-26 16:49:47 -07:00
internal.h mm: thp: tail page refcounting fix 2011-11-02 16:06:57 -07:00
Kconfig Merge branch 'master' into x86/memblock 2011-11-28 09:46:22 -08:00
Kconfig.debug mm: more intensive memory corruption debugging 2012-01-10 16:30:42 -08:00
kmemcheck.c
kmemleak-test.c
kmemleak.c kmemleak: Disable early logging when kmemleak is off by default 2012-01-20 16:57:05 +00:00
ksm.c memcg: fix GPF when cgroup removal races with last exit 2012-03-05 15:49:43 -08:00
maccess.c mm: Map most files to use export.h instead of module.h 2011-10-31 09:20:12 -04:00
madvise.c fs: kill i_alloc_sem 2011-07-20 20:47:46 -04:00
Makefile Cross Memory Attach 2011-10-31 17:30:44 -07:00
memblock.c memblock: Fix size aligning of memblock_alloc_base_nid() 2012-03-01 10:53:18 +01:00
memcontrol.c memcg: fix GPF when cgroup removal races with last exit 2012-03-05 15:49:43 -08:00
memory-failure.c mm: compaction: introduce sync-light migration for use by compaction 2012-01-12 20:13:09 -08:00
memory.c mm: fix rss count leakage during migration 2012-01-23 08:38:49 -08:00
memory_hotplug.c mm: compaction: introduce sync-light migration for use by compaction 2012-01-12 20:13:09 -08:00
mempolicy.c mm: compaction: introduce sync-light migration for use by compaction 2012-01-12 20:13:09 -08:00
mempool.c mempool: fix first round failure behavior 2012-01-10 16:30:45 -08:00
migrate.c memcg: fix GPF when cgroup removal races with last exit 2012-03-05 15:49:43 -08:00
mincore.c mm: clarify the radix_tree exceptional cases 2011-08-03 14:25:24 -10:00
mlock.c Merge branch 'modsplit-Oct31_2011' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux 2011-11-06 19:44:47 -08:00
mm_init.c mm: Map most files to use export.h instead of module.h 2011-10-31 09:20:12 -04:00
mmap.c mm: simplify find_vma_prev() 2012-01-10 16:30:44 -08:00
mmu_context.c mm: Map most files to use export.h instead of module.h 2011-10-31 09:20:12 -04:00
mmu_notifier.c mm: Map most files to use export.h instead of module.h 2011-10-31 09:20:12 -04:00
mmzone.c mm: delete various needless include <linux/module.h> 2011-10-31 09:20:11 -04:00
mprotect.c
mremap.c mremap: enforce rmap src/dst vma ordering in case of vma_merge() succeeding in copy_vma() 2012-01-10 16:30:44 -08:00
msync.c
nobootmem.c Merge branch 'master' into x86/memblock 2011-11-28 09:46:22 -08:00
nommu.c NOMMU: Don't need to clear vm_mm when deleting a VMA 2012-02-24 08:59:04 -08:00
oom_kill.c mm: unify remaining mem_cont, mem, etc. variable names to memcg 2012-01-12 20:13:06 -08:00
page-writeback.c Merge branch 'writeback-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/wfg/linux 2012-01-10 16:59:59 -08:00
page_alloc.c vfs: fix panic in __d_lookup() with high dentry hashtable counts 2012-02-13 20:45:38 -05:00
page_cgroup.c page_cgroup: drop multi CONFIG_MEMORY_HOTPLUG 2012-01-12 20:13:08 -08:00
page_io.c
page_isolation.c
pagewalk.c pagewalk: fix code comment for THP 2011-07-25 20:57:09 -07:00
percpu-km.c
percpu-vm.c percpu: fix chunk range calculation 2011-11-22 08:09:46 -08:00
percpu.c Kmemleak patches 2012-01-14 18:11:11 -08:00
pgtable-generic.c
prio_tree.c
process_vm_access.c Fix race in process_vm_rw_core 2012-02-02 12:55:17 -08:00
quicklist.c mm: delete various needless include <linux/module.h> 2011-10-31 09:20:11 -04:00
readahead.c mm: Map most files to use export.h instead of module.h 2011-10-31 09:20:12 -04:00
rmap.c mm: unify remaining mem_cont, mem, etc. variable names to memcg 2012-01-12 20:13:06 -08:00
shmem.c SHM_UNLOCK: fix Unevictable pages stranded after swap 2012-01-23 08:38:48 -08:00
slab.c Merge branch 'slab/for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/penberg/linux 2012-01-11 18:52:23 -08:00
slob.c mm: Map most files to use export.h instead of module.h 2011-10-31 09:20:12 -04:00
slub.c mm,x86,um: move CMPXCHG_DOUBLE config option 2012-01-12 20:13:03 -08:00
sparse-vmemmap.c mm: delete various needless include <linux/module.h> 2011-10-31 09:20:11 -04:00
sparse.c mm: Map most files to use export.h instead of module.h 2011-10-31 09:20:12 -04:00
swap.c memcg: fix GPF when cgroup removal races with last exit 2012-03-05 15:49:43 -08:00
swap_state.c memcg: fix GPF when cgroup removal races with last exit 2012-03-05 15:49:43 -08:00
swapfile.c mm: unify remaining mem_cont, mem, etc. variable names to memcg 2012-01-12 20:13:06 -08:00
thrash.c mm/thrash.c: quiet sparse noise 2011-10-31 17:30:50 -07:00
truncate.c mm: Map most files to use export.h instead of module.h 2011-10-31 09:20:12 -04:00
util.c mm: Map most files to use export.h instead of module.h 2011-10-31 09:20:12 -04:00
vmalloc.c mm/vmalloc.c: eliminate extra loop in pcpu_get_vm_areas error path 2012-01-12 20:13:10 -08:00
vmscan.c SHM_UNLOCK: fix Unevictable pages stranded after swap 2012-01-23 08:38:48 -08:00
vmstat.c mm,x86,um: move CMPXCHG_LOCAL config option 2012-01-12 20:13:03 -08:00