tree bfb131721b8c96464041d2919b80a4e487a47a2f
parent 1b5ad24878b7e5a543b98c5d2f8c0d8c0dd3088f
author Carsten Otte <cotte@de.ibm.com> 1281111562 +0200
committer Pekka Enberg <penberg@kernel.org> 1281368887 +0300

slab: fix object alignment

This patch fixes alignment of slab objects in case CONFIG_DEBUG_PAGEALLOC is
active.
Before this spot in kmem_cache_create, we have this situation:
- align contains the required alignment of the object
- cachep->obj_offset is 0 or equals align in case of CONFIG_DEBUG_SLAB
- size equals the size of the object, or object plus trailing redzone in case
  of CONFIG_DEBUG_SLAB

This spot tries to fill one page per object if the object is in certain size
limits, however setting obj_offset to PAGE_SIZE - size does break the object
alignment since size may not be aligned with the required alignment.
This patch simply adds an ALIGN(size, align) to the equation and fixes the
object size detection accordingly.

This code in drivers/s390/cio/qdio_setup_init has lead to incorrectly aligned
slab objects (sizeof(struct qdio_q) equals 1792):
	qdio_q_cache = kmem_cache_create("qdio_q", sizeof(struct qdio_q),
					 256, 0, NULL);

Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Carsten Otte <cotte@de.ibm.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>