[PATCH] slab: fix crash on __drain_alien_cahce() during CPU Hotplug

transfer_objects should only be called when all of the cpus in the
node are online.  CPU_DEAD notifier callback marks l3->shared to NULL.

Signed-off-by: Jacob Shin <jacob.shin@amd.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 2 insertions, 1 deletions

diff --git a/mm/slab.c b/mm/slab.c
index af5c5237e11..c32af7e7581 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -979,7 +979,8 @@ static void __drain_alien_cache(struct kmem_cache *cachep,
                  * That way we could avoid the overhead of putting the objects
                  * into the free lists and getting them back later.
                  */
-                transfer_objects(rl3->shared, ac, ac->limit);
+                if (rl3->shared)
+                        transfer_objects(rl3->shared, ac, ac->limit);
 
                 free_block(cachep, ac->entry, ac->avail, node);
                 ac->avail = 0;