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Commit 5c5e3b33 authored by Shiyong Li's avatar Shiyong Li Committed by Pekka Enberg
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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: default avatarShiyong Li <shi-yong.li@motorola.com>
Signed-off-by: default avatarPekka Enberg <penberg@cs.helsinki.fi>
parent 0d0fb0f9

mm/slab.c

+4 −4
Original line number Original line Diff line number Diff line
@@ -2220,8 +2220,8 @@ kmem_cache_create (const char *name, size_t size, size_t align, 
	if (ralign < align) {

	if (ralign < align) {

		ralign = align;

		ralign = align;

	}

	}

	/* disable debug if necessary */

	/* disable debug if not aligning with REDZONE_ALIGN */

	if (ralign > __alignof__(unsigned long long))

	if (ralign & (__alignof__(unsigned long long) - 1))

		flags &= ~(SLAB_RED_ZONE | SLAB_STORE_USER);

		flags &= ~(SLAB_RED_ZONE | SLAB_STORE_USER);

	/*

	/*

	 * 4) Store it.

	 * 4) Store it.
@@ -2247,8 +2247,8 @@ kmem_cache_create (const char *name, size_t size, size_t align, 
	 */

	 */

	if (flags & SLAB_RED_ZONE) {

	if (flags & SLAB_RED_ZONE) {

		/* add space for red zone words */

		/* add space for red zone words */

		cachep->obj_offset += sizeof(unsigned long long);

		cachep->obj_offset += align;

		size += 2 * sizeof(unsigned long long);

		size += align + sizeof(unsigned long long);

	}

	}

	if (flags & SLAB_STORE_USER) {

	if (flags & SLAB_STORE_USER) {

		/* user store requires one word storage behind the end of

		/* user store requires one word storage behind the end of