memcg: avoid accessing memcg after releasing reference

This might cause a use-after-free bug. Signed-off-by: Li Zefan <[email protected]> Cc: Glauber Costa <[email protected]> Acked-by: Michal Hocko <[email protected]> Acked-by: KAMEZAWA Hiroyuki <[email protected]> Cc: Johannes Weiner <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
kishon · Apr 29, 2013 · fd0ccaf · fd0ccaf
1 parent 865ffef
commit fd0ccaf
Showing 1 changed file with 1 addition and 1 deletion.
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
@@ -3215,12 +3215,12 @@ void memcg_release_cache(struct kmem_cache *s)
 
 	root = s->memcg_params->root_cache;
 	root->memcg_params->memcg_caches[id] = NULL;
-	mem_cgroup_put(memcg);
 
 	mutex_lock(&memcg->slab_caches_mutex);
 	list_del(&s->memcg_params->list);
 	mutex_unlock(&memcg->slab_caches_mutex);
 
+	mem_cgroup_put(memcg);
 out:
 	kfree(s->memcg_params);
 }