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authorPekka Enberg <penberg@cs.helsinki.fi>2006-09-26 02:31:25 -0400
committerLinus Torvalds <torvalds@g5.osdl.org>2006-09-26 11:48:48 -0400
commitca5f9703dffa012cc46166e6206c5a992910e041 (patch)
treed1fb19019db14465eb8674aa1b13c6506a569705
parentdb37648cd6ce9b828abd6d49aa3d269926ee7b7d (diff)
[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>
-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,
2096 } else { 2096 } else {
2097 ralign = BYTES_PER_WORD; 2097 ralign = BYTES_PER_WORD;
2098 } 2098 }
2099
2100 /*
2101 * Redzoning and user store require word alignment. Note this will be
2102 * overridden by architecture or caller mandated alignment if either
2103 * is greater than BYTES_PER_WORD.
2104 */
2105 if (flags & SLAB_RED_ZONE || flags & SLAB_STORE_USER)
2106 ralign = BYTES_PER_WORD;
2107
2099 /* 2) arch mandated alignment: disables debug if necessary */ 2108 /* 2) arch mandated alignment: disables debug if necessary */
2100 if (ralign < ARCH_SLAB_MINALIGN) { 2109 if (ralign < ARCH_SLAB_MINALIGN) {
2101 ralign = ARCH_SLAB_MINALIGN; 2110 ralign = ARCH_SLAB_MINALIGN;
@@ -2109,8 +2118,7 @@ kmem_cache_create (const char *name, size_t size, size_t align,
2109 flags &= ~(SLAB_RED_ZONE | SLAB_STORE_USER); 2118 flags &= ~(SLAB_RED_ZONE | SLAB_STORE_USER);
2110 } 2119 }
2111 /* 2120 /*
2112 * 4) Store it. Note that the debug code below can reduce 2121 * 4) Store it.
2113 * the alignment to BYTES_PER_WORD.
2114 */ 2122 */
2115 align = ralign; 2123 align = ralign;
2116 2124
@@ -2122,20 +2130,19 @@ kmem_cache_create (const char *name, size_t size, size_t align,
2122#if DEBUG 2130#if DEBUG
2123 cachep->obj_size = size; 2131 cachep->obj_size = size;
2124 2132
2133 /*
2134 * Both debugging options require word-alignment which is calculated
2135 * into align above.
2136 */
2125 if (flags & SLAB_RED_ZONE) { 2137 if (flags & SLAB_RED_ZONE) {
2126 /* redzoning only works with word aligned caches */
2127 align = BYTES_PER_WORD;
2128
2129 /* add space for red zone words */ 2138 /* add space for red zone words */
2130 cachep->obj_offset += BYTES_PER_WORD; 2139 cachep->obj_offset += BYTES_PER_WORD;
2131 size += 2 * BYTES_PER_WORD; 2140 size += 2 * BYTES_PER_WORD;
2132 } 2141 }
2133 if (flags & SLAB_STORE_USER) { 2142 if (flags & SLAB_STORE_USER) {
2134 /* user store requires word alignment and 2143 /* user store requires one word storage behind the end of
2135 * one word storage behind the end of the real 2144 * the real object.
2136 * object.
2137 */ 2145 */
2138 align = BYTES_PER_WORD;
2139 size += BYTES_PER_WORD; 2146 size += BYTES_PER_WORD;
2140 } 2147 }
2141#if FORCED_DEBUG && defined(CONFIG_DEBUG_PAGEALLOC) 2148#if FORCED_DEBUG && defined(CONFIG_DEBUG_PAGEALLOC)