slab: Fix missing DEBUG_SLAB last user (5c5e3b33) · Commits · 戴 / test

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>

mm/slab.c

+4 −4

Original line number	Diff line number	Diff line
		@@ -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

Admin message