The patch titled
Subject: mm: fix slab->page _count corruption when using slub
has been added to the -mm tree. Its filename is
mm-fix-slab-page-_count-corruption-when-using-slub.patch
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From: Pravin B Shelar <pshelar@xxxxxxxxxx>
Subject: 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.
Reported-by: Amey Bhide <abhide@xxxxxxxxxx>
Signed-off-by: Pravin B Shelar <pshelar@xxxxxxxxxx>
Acked-by: Christoph Lameter <cl@xxxxxxxxx>
Cc: Pekka Enberg <penberg@xxxxxxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/mm_types.h | 8 ++++++++
1 file changed, 8 insertions(+)
diff -puN include/linux/mm_types.h~mm-fix-slab-page-_count-corruption-when-using-slub include/linux/mm_types.h
--- a/include/linux/mm_types.h~mm-fix-slab-page-_count-corruption-when-using-slub
+++ a/include/linux/mm_types.h
@@ -57,8 +57,16 @@ 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 rest of double word is protected by slab_lock
+ * but _count is not. */
+ unsigned counters;
+#endif
struct {
_
Subject: Subject: mm: fix slab->page _count corruption when using slub
Patches currently in -mm which might be from pshelar@xxxxxxxxxx are
mm-fix-slab-page-_count-corruption-when-using-slub.patch
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