SLUB: fix ARCH_KMALLOC_MINALIGN cases 64 and 256
If the minalign is 64 bytes, then the 96 byte cache should not be created
because it would conflict with the 128 byte cache.
If the minalign is 256 bytes, patching the size_index table should not
result in a buffer overrun.
The calculation "(i - 1) / 8" used to access size_index[] is moved to
a separate function as suggested by Christoph Lameter.
Acked-by: Christoph Lameter <cl@linux-foundation.org>
Signed-off-by: Aaro Koskinen <aaro.koskinen@nokia.com>
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h
index 4dcbc2c..aa5d4a6 100644
--- a/include/linux/slub_def.h
+++ b/include/linux/slub_def.h
@@ -152,12 +152,10 @@
if (size <= KMALLOC_MIN_SIZE)
return KMALLOC_SHIFT_LOW;
-#if KMALLOC_MIN_SIZE <= 64
- if (size > 64 && size <= 96)
+ if (KMALLOC_MIN_SIZE <= 32 && size > 64 && size <= 96)
return 1;
- if (size > 128 && size <= 192)
+ if (KMALLOC_MIN_SIZE <= 64 && size > 128 && size <= 192)
return 2;
-#endif
if (size <= 8) return 3;
if (size <= 16) return 4;
if (size <= 32) return 5;
diff --git a/mm/slub.c b/mm/slub.c
index e16c9fb..be493bd 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2825,6 +2825,11 @@
2 /* 192 */
};
+static inline int size_index_elem(size_t bytes)
+{
+ return (bytes - 1) / 8;
+}
+
static struct kmem_cache *get_slab(size_t size, gfp_t flags)
{
int index;
@@ -2833,7 +2838,7 @@
if (!size)
return ZERO_SIZE_PTR;
- index = size_index[(size - 1) / 8];
+ index = size_index[size_index_elem(size)];
} else
index = fls(size - 1);
@@ -3188,10 +3193,12 @@
slab_state = PARTIAL;
/* Caches that are not of the two-to-the-power-of size */
- if (KMALLOC_MIN_SIZE <= 64) {
+ if (KMALLOC_MIN_SIZE <= 32) {
create_kmalloc_cache(&kmalloc_caches[1],
"kmalloc-96", 96, GFP_NOWAIT);
caches++;
+ }
+ if (KMALLOC_MIN_SIZE <= 64) {
create_kmalloc_cache(&kmalloc_caches[2],
"kmalloc-192", 192, GFP_NOWAIT);
caches++;
@@ -3218,17 +3225,28 @@
BUILD_BUG_ON(KMALLOC_MIN_SIZE > 256 ||
(KMALLOC_MIN_SIZE & (KMALLOC_MIN_SIZE - 1)));
- for (i = 8; i < KMALLOC_MIN_SIZE; i += 8)
- size_index[(i - 1) / 8] = KMALLOC_SHIFT_LOW;
+ for (i = 8; i < KMALLOC_MIN_SIZE; i += 8) {
+ int elem = size_index_elem(i);
+ if (elem >= ARRAY_SIZE(size_index))
+ break;
+ size_index[elem] = KMALLOC_SHIFT_LOW;
+ }
- if (KMALLOC_MIN_SIZE == 128) {
+ if (KMALLOC_MIN_SIZE == 64) {
+ /*
+ * The 96 byte size cache is not used if the alignment
+ * is 64 byte.
+ */
+ for (i = 64 + 8; i <= 96; i += 8)
+ size_index[size_index_elem(i)] = 7;
+ } else if (KMALLOC_MIN_SIZE == 128) {
/*
* The 192 byte sized cache is not used if the alignment
* is 128 byte. Redirect kmalloc to use the 256 byte cache
* instead.
*/
for (i = 128 + 8; i <= 192; i += 8)
- size_index[(i - 1) / 8] = 8;
+ size_index[size_index_elem(i)] = 8;
}
slab_state = UP;