diff options
| author | Pravin B Shelar | 2012-06-20 12:52:56 -0700 |
|---|---|---|
| committer | Linus Torvalds | 2012-06-20 14:39:35 -0700 |
| commit | abca7c4965845924f65d40e0aa1092bdd895e314 (patch) | |
| tree | 18d908b58243b6f46cadfa4515d6370299c88d3f | |
| parent | 485802a6c524e62b5924849dd727ddbb1497cc71 (diff) | |
mm: fix slab->page _count corruption when using slub
On arches that do not support this_cpu_cmpxchg_double() slab_lock is used
to do atomic cmpxchg() on double word which contains page->_count. The
page count can be changed from get_page() or put_page() without taking
slab_lock. That corrupts page counter.
Fix it by moving page->_count out of cmpxchg_double data. So that slub
does no change it while updating slub meta-data in struct page.
[akpm@linux-foundation.org: use standard comment layout, tweak comment text]
Reported-by: Amey Bhide <abhide@nicira.com>
Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | include/linux/mm_types.h | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index dad95bdd06d7..704a626d94a0 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -57,8 +57,18 @@ struct page { }; union { +#if defined(CONFIG_HAVE_CMPXCHG_DOUBLE) && \ + defined(CONFIG_HAVE_ALIGNED_STRUCT_PAGE) /* Used for cmpxchg_double in slub */ unsigned long counters; +#else + /* + * Keep _count separate from slub cmpxchg_double data. + * As the rest of the double word is protected by + * slab_lock but _count is not. + */ + unsigned counters; +#endif struct { |