Subject: Fix off by one error in slab.h
We ran into some strange issues as a result of an off by one isse in slab.h
The root of the issue is the treatment of KMALLOC_SHIFT_HIGH that is confusing.
Make KMALLOC_SHIFT_HIGH the first unsupported size instead of the last
supported.
Signed-off-by: Christoph Lameter <c...@linux.com>
Index: linux/include/linux/slab.h
===================================================================
--- linux.orig/include/linux/slab.h 2013-04-30 09:54:23.636533564 -0500
+++ linux/include/linux/slab.h 2013-04-30 10:10:35.676932866 -0500
@@ -176,8 +176,8 @@ struct kmem_cache {
* to do various tricks to work around compiler limitations in order to
* ensure proper constant folding.
*/
-#define KMALLOC_SHIFT_HIGH ((MAX_ORDER + PAGE_SHIFT - 1) <= 25 ? \
- (MAX_ORDER + PAGE_SHIFT - 1) : 25)
+#define KMALLOC_SHIFT_HIGH ((MAX_ORDER + PAGE_SHIFT) <= 26 ? \
+ (MAX_ORDER + PAGE_SHIFT) : 26)
#define KMALLOC_SHIFT_MAX KMALLOC_SHIFT_HIGH
#define KMALLOC_SHIFT_LOW 5
#else
@@ -185,7 +185,7 @@ struct kmem_cache {
* SLUB allocates up to order 2 pages directly and otherwise
* passes the request to the page allocator.
*/
-#define KMALLOC_SHIFT_HIGH (PAGE_SHIFT + 1)
+#define KMALLOC_SHIFT_HIGH (PAGE_SHIFT + 2)
#define KMALLOC_SHIFT_MAX (MAX_ORDER + PAGE_SHIFT)
#define KMALLOC_SHIFT_LOW 3
#endif
@@ -193,7 +193,7 @@ struct kmem_cache {
/* Maximum allocatable size */
#define KMALLOC_MAX_SIZE (1UL << KMALLOC_SHIFT_MAX)
/* Maximum size for which we actually use a slab cache */
-#define KMALLOC_MAX_CACHE_SIZE (1UL << KMALLOC_SHIFT_HIGH)
+#define KMALLOC_MAX_CACHE_SIZE ((1UL << (KMALLOC_SHIFT_HIGH -1)))
/* Maximum order allocatable via the slab allocagtor */
#define KMALLOC_MAX_ORDER (KMALLOC_SHIFT_MAX - PAGE_SHIFT)
@@ -206,9 +206,9 @@ struct kmem_cache {
#define KMALLOC_MIN_SIZE (1 << KMALLOC_SHIFT_LOW)
#endif
-extern struct kmem_cache *kmalloc_caches[KMALLOC_SHIFT_HIGH + 1];
+extern struct kmem_cache *kmalloc_caches[KMALLOC_SHIFT_HIGH];
#ifdef CONFIG_ZONE_DMA
-extern struct kmem_cache *kmalloc_dma_caches[KMALLOC_SHIFT_HIGH + 1];
+extern struct kmem_cache *kmalloc_dma_caches[KMALLOC_SHIFT_HIGH];
#endif
/*
Index: linux/mm/slab_common.c
===================================================================
--- linux.orig/mm/slab_common.c 2013-04-30 09:54:23.636533564 -0500
+++ linux/mm/slab_common.c 2013-04-30 09:54:53.693039252 -0500
@@ -319,11 +319,11 @@ struct kmem_cache *__init create_kmalloc
return s;
}
-struct kmem_cache *kmalloc_caches[KMALLOC_SHIFT_HIGH + 1];
+struct kmem_cache *kmalloc_caches[KMALLOC_SHIFT_HIGH];
EXPORT_SYMBOL(kmalloc_caches);
#ifdef CONFIG_ZONE_DMA
-struct kmem_cache *kmalloc_dma_caches[KMALLOC_SHIFT_HIGH + 1];
+struct kmem_cache *kmalloc_dma_caches[KMALLOC_SHIFT_HIGH];
EXPORT_SYMBOL(kmalloc_dma_caches);
#endif
@@ -446,7 +446,7 @@ void __init create_kmalloc_caches(unsign
if (KMALLOC_MIN_SIZE <= 64 && !kmalloc_caches[2])
kmalloc_caches[2] = create_kmalloc_cache(NULL, 192, flags);
- for (i = KMALLOC_SHIFT_LOW; i <= KMALLOC_SHIFT_HIGH; i++)
+ for (i = KMALLOC_SHIFT_LOW; i < KMALLOC_SHIFT_HIGH; i++)
if (!kmalloc_caches[i])
kmalloc_caches[i] = create_kmalloc_cache(NULL,
1 << i, flags);
@@ -454,7 +454,7 @@ void __init create_kmalloc_caches(unsign
/* Kmalloc array is now usable */
slab_state = UP;
- for (i = 0; i <= KMALLOC_SHIFT_HIGH; i++) {
+ for (i = 0; i < KMALLOC_SHIFT_HIGH; i++) {
struct kmem_cache *s = kmalloc_caches[i];
char *n;
@@ -467,7 +467,7 @@ void __init create_kmalloc_caches(unsign
}
#ifdef CONFIG_ZONE_DMA
- for (i = 0; i <= KMALLOC_SHIFT_HIGH; i++) {
+ for (i = 0; i < KMALLOC_SHIFT_HIGH; i++) {
struct kmem_cache *s = kmalloc_caches[i];
if (s) {
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
