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slab: Fix missing DEBUG_SLAB last user 

Even with SLAB_RED_ZONE and SLAB_STORE_USER enabled, kernel would NOT store
redzone and last user data around allocated memory space if "arch cache line >
sizeof(unsigned long long)". As a result, last user information is unexpectedly
MISSED while dumping slab corruption log.

This fix makes sure that redzone and last user tags get stored unless the
required alignment breaks redzone's.

Signed-off-by: Shiyong Li <shi-yong.li@motorola.com>
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
This commit is contained in:
Shiyong Li 2010-04-12 13:48:21 +08:00 committed by Pekka Enberg
parent 0d0fb0f9c5
commit 5c5e3b33b7
1 changed files with 4 additions and 4 deletions
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8
mm/slab.c
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@ -2220,8 +2220,8 @@ kmem_cache_create (const char *name, size_t size, size_t align,
if (ralign < align) {
ralign = align;
}
/* disable debug if necessary */
if (ralign > __alignof__(unsigned long long))
/* disable debug if not aligning with REDZONE_ALIGN */
if (ralign & (__alignof__(unsigned long long) - 1))
flags &= ~(SLAB_RED_ZONE | SLAB_STORE_USER);
/*
* 4) Store it.
@ -2247,8 +2247,8 @@ kmem_cache_create (const char *name, size_t size, size_t align,
*/
if (flags & SLAB_RED_ZONE) {
/* add space for red zone words */
cachep->obj_offset += sizeof(unsigned long long);
size += 2 * sizeof(unsigned long long);
cachep->obj_offset += align;
size += align + sizeof(unsigned long long);
}
if (flags & SLAB_STORE_USER) {
/* user store requires one word storage behind the end of