Merge branch 'slab/urgent' of git://git.kernel.org/pub/scm/linux/kernel/git/penberg/slab-2.6

* 'slab/urgent' of git://git.kernel.org/pub/scm/linux/kernel/git/penberg/slab-2.6:
slub: Fix kmem_cache_destroy() with SLAB_DESTROY_BY_RCU

mm/slub.c

···
  */
 void kmem_cache_destroy(struct kmem_cache *s)
 {
-	if (s->flags & SLAB_DESTROY_BY_RCU)
-		rcu_barrier();
 	down_write(&slub_lock);
 	s->refcount--;
 	if (!s->refcount) {
···
 				"still has objects.\n", s->name, __func__);
 			dump_stack();
 		}
+		if (s->flags & SLAB_DESTROY_BY_RCU)
+			rcu_barrier();
 		sysfs_slab_remove(s);
 	} else
 		up_write(&slub_lock);