diff options
| -rw-r--r-- | mm/slab.c | 32 |
1 files changed, 23 insertions, 9 deletions
@@ -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 |
