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authorPekka Enberg <penberg@cs.helsinki.fi>2006-09-25 23:31:25 -0700
committerLinus Torvalds <torvalds@g5.osdl.org>2006-09-26 08:48:48 -0700
commitca5f9703dffa012cc46166e6206c5a992910e041 (patch)
treed1fb19019db14465eb8674aa1b13c6506a569705 /mm
parentdb37648cd6ce9b828abd6d49aa3d269926ee7b7d (diff)
downloadlinux-sh-ca5f9703dffa012cc46166e6206c5a992910e041.tar.gz
[PATCH] slab: respect architecture and caller mandated alignment
As explained by Heiko, on s390 (32-bit) ARCH_KMALLOC_MINALIGN is set to eight because their common I/O layer allocates data structures that need to have an eight byte alignment. This does not work when CONFIG_SLAB_DEBUG is enabled because kmem_cache_create will override alignment to BYTES_PER_WORD which is four. So change kmem_cache_create to ensure cache alignment is always at minimum what the architecture or caller mandates even if slab debugging is enabled. Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Christoph Lameter <clameter@sgi.com> Signed-off-by: Manfred Spraul <manfred@colorfullife.com> Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/slab.c25
1 files changed, 16 insertions, 9 deletions
diff --git a/mm/slab.c b/mm/slab.c
index 00584dbbec03..d47d0e186973 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -2096,6 +2096,15 @@ kmem_cache_create (const char *name, size_t size, size_t align,
} else {
ralign = BYTES_PER_WORD;
}
+
+ /*
+ * Redzoning and user store require word alignment. Note this will be
+ * overridden by architecture or caller mandated alignment if either
+ * is greater than BYTES_PER_WORD.
+ */
+ if (flags & SLAB_RED_ZONE || flags & SLAB_STORE_USER)
+ ralign = BYTES_PER_WORD;
+
/* 2) arch mandated alignment: disables debug if necessary */
if (ralign < ARCH_SLAB_MINALIGN) {
ralign = ARCH_SLAB_MINALIGN;
@@ -2109,8 +2118,7 @@ kmem_cache_create (const char *name, size_t size, size_t align,
flags &= ~(SLAB_RED_ZONE | SLAB_STORE_USER);
}
/*
- * 4) Store it. Note that the debug code below can reduce
- * the alignment to BYTES_PER_WORD.
+ * 4) Store it.
*/
align = ralign;
@@ -2122,20 +2130,19 @@ kmem_cache_create (const char *name, size_t size, size_t align,
#if DEBUG
cachep->obj_size = size;
+ /*
+ * Both debugging options require word-alignment which is calculated
+ * into align above.
+ */
if (flags & SLAB_RED_ZONE) {
- /* redzoning only works with word aligned caches */
- align = BYTES_PER_WORD;
-
/* add space for red zone words */
cachep->obj_offset += BYTES_PER_WORD;
size += 2 * BYTES_PER_WORD;
}
if (flags & SLAB_STORE_USER) {
- /* user store requires word alignment and
- * one word storage behind the end of the real
- * object.
+ /* user store requires one word storage behind the end of
+ * the real object.
*/
- align = BYTES_PER_WORD;
size += BYTES_PER_WORD;
}
#if FORCED_DEBUG && defined(CONFIG_DEBUG_PAGEALLOC)