On 7/2/13 10:12 PM, Andrew Morton wrote:
On Tue, 2 Jul 2013 21:49:26 +0900 Tetsuo Handa 
<[email protected]> wrote:

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.

Nice, thanks.  Pekka, please grab.


From: Christoph Lameter <[email protected]>
Subject: slab: fix init_lock_keys

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 <[email protected]>
Reported-by: Tetsuo Handa <[email protected]>
Cc: Pekka Enberg <[email protected]>
Cc: <[email protected]>      [3.10.x]
Signed-off-by: Andrew Morton <[email protected]>
---

  mm/slab.c |    2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

diff -puN mm/slab.c~slab-fix-init_lock_keys mm/slab.c
--- a/mm/slab.c~slab-fix-init_lock_keys
+++ a/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];

_


Grabbed, thanks a lot Andrew!
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