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-rw-r--r--mm/slab.c32
1 files changed, 23 insertions, 9 deletions
diff --git a/mm/slab.c b/mm/slab.c
index a9c4472e920..b344e670712 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -137,6 +137,7 @@
/* Shouldn't this be in a header file somewhere? */
#define BYTES_PER_WORD sizeof(void *)
+#define REDZONE_ALIGN max(BYTES_PER_WORD, __alignof__(unsigned long long))
#ifndef cache_line_size
#define cache_line_size() L1_CACHE_BYTES
@@ -547,7 +548,7 @@ static unsigned long long *dbg_redzone2(struct kmem_cache *cachep, void *objp)
if (cachep->flags & SLAB_STORE_USER)
return (unsigned long long *)(objp + cachep->buffer_size -
sizeof(unsigned long long) -
- BYTES_PER_WORD);
+ REDZONE_ALIGN);
return (unsigned long long *) (objp + cachep->buffer_size -
sizeof(unsigned long long));
}
@@ -2178,7 +2179,8 @@ kmem_cache_create (const char *name, size_t size, size_t align,
* above the next power of two: caches with object sizes just above a
* power of two have a significant amount of internal fragmentation.
*/
- if (size < 4096 || fls(size - 1) == fls(size-1 + 3 * BYTES_PER_WORD))
+ if (size < 4096 || fls(size - 1) == fls(size-1 + REDZONE_ALIGN +
+ 2 * sizeof(unsigned long long)))
flags |= SLAB_RED_ZONE | SLAB_STORE_USER;
if (!(flags & SLAB_DESTROY_BY_RCU))
flags |= SLAB_POISON;
@@ -2219,12 +2221,20 @@ kmem_cache_create (const char *name, size_t size, size_t align,
}
/*
- * 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.
+ * Redzoning and user store require word alignment or possibly larger.
+ * 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 = __alignof__(unsigned long long);
+ if (flags & SLAB_STORE_USER)
+ ralign = BYTES_PER_WORD;
+
+ if (flags & SLAB_RED_ZONE) {
+ ralign = REDZONE_ALIGN;
+ /* If redzoning, ensure that the second redzone is suitably
+ * aligned, by adjusting the object size accordingly. */
+ size += REDZONE_ALIGN - 1;
+ size &= ~(REDZONE_ALIGN - 1);
+ }
/* 2) arch mandated alignment */
if (ralign < ARCH_SLAB_MINALIGN) {
@@ -2261,9 +2271,13 @@ kmem_cache_create (const char *name, size_t size, size_t align,
}
if (flags & SLAB_STORE_USER) {
/* user store requires one word storage behind the end of
- * the real object.
+ * the real object. But if the second red zone needs to be
+ * aligned to 64 bits, we must allow that much space.
*/
- size += BYTES_PER_WORD;
+ if (flags & SLAB_RED_ZONE)
+ size += REDZONE_ALIGN;
+ else
+ size += BYTES_PER_WORD;
}
#if FORCED_DEBUG && defined(CONFIG_DEBUG_PAGEALLOC)
if (size >= malloc_sizes[INDEX_L3 + 1].cs_size