slab: fix init_lock_keys

commit 0f8f8094d28eb53368ac09186ea6b3a324cc7d44 upstream.

Some architectures (e.g. powerpc built with CONFIG_PPC_256K_PAGES=y
CONFIG_FORCE_MAX_ZONEORDER=11) get PAGE_SHIFT + MAX_ORDER > 26.

In 3.10 kernels, CONFIG_LOCKDEP=y with PAGE_SHIFT + MAX_ORDER > 26 makes
init_lock_keys() dereference beyond kmalloc_caches[26].
This leads to an unbootable system (kernel panic at initializing SLAB)
if one of kmalloc_caches[26...PAGE_SHIFT+MAX_ORDER-1] is not NULL.

Fix this by making sure that init_lock_keys() does not dereference beyond
kmalloc_caches[26] arrays.

Signed-off-by: Christoph Lameter <cl@linux.com>
Reported-by: Tetsuo Handa <penguin-kernel@I-Love.SAKURA.ne.jp>
Cc: Pekka Enberg <penberg@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/mm/slab.c b/mm/slab.c
index 8ccd296..bd88411 100644 (file)
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -565,7 +565,7 @@ static void init_node_lock_keys(int q)
        if (slab_state < UP)
                return;
 
-       for (i = 1; i < PAGE_SHIFT + MAX_ORDER; i++) {
+       for (i = 1; i <= KMALLOC_SHIFT_HIGH; i++) {
                struct kmem_cache_node *n;
                struct kmem_cache *cache = kmalloc_caches[i];