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>
diff --git a/mm/slab.c b/mm/slab.c
index bac0f4f..525c664 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -2220,8 +2220,8 @@
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 @@
*/
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