Fix slab redzone alignment

[pandora-kernel.git] / mm / slab.c

diff --git a/mm/slab.c b/mm/slab.c
index a9c4472..b344e67 100644 (file)
--- 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