1 files changed, 18 insertions, 7 deletions

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 322d18dc17f0..014a4f1acf1c 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3270,9 +3270,6 @@ void memcg_register_cache(struct kmem_cache *s)
 
         css_get(&memcg->css);
 
-        mutex_lock(&memcg->slab_caches_mutex);
-        list_add(&s->memcg_params->list, &memcg->memcg_slab_caches);
-        mutex_unlock(&memcg->slab_caches_mutex);
 
         /*
          * Since readers won't lock (see cache_from_memcg_idx()), we need a
@@ -3281,7 +3278,16 @@ void memcg_register_cache(struct kmem_cache *s)
          */
         smp_wmb();
 
+        /*
+         * Initialize the pointer to this cache in its parent's memcg_params
+         * before adding it to the memcg_slab_caches list, otherwise we can
+         * fail to convert memcg_params_to_cache() while traversing the list.
+         */
         root->memcg_params->memcg_caches[id] = s;
+
+        mutex_lock(&memcg->slab_caches_mutex);
+        list_add(&s->memcg_params->list, &memcg->memcg_slab_caches);
+        mutex_unlock(&memcg->slab_caches_mutex);
 }
 
 void memcg_unregister_cache(struct kmem_cache *s)
@@ -3293,16 +3299,21 @@ void memcg_unregister_cache(struct kmem_cache *s)
         if (is_root_cache(s))
                 return;
 
-        memcg = s->memcg_params->memcg;
-        id  = memcg_cache_id(memcg);
-
         root = s->memcg_params->root_cache;
-        root->memcg_params->memcg_caches[id] = NULL;
+        memcg = s->memcg_params->memcg;
+        id = memcg_cache_id(memcg);
 
         mutex_lock(&memcg->slab_caches_mutex);
         list_del(&s->memcg_params->list);
         mutex_unlock(&memcg->slab_caches_mutex);
 
+        /*
+         * Clear the pointer to this cache in its parent's memcg_params only
+         * after removing it from the memcg_slab_caches list, otherwise we can
+         * fail to convert memcg_params_to_cache() while traversing the list.
+         */
+        root->memcg_params->memcg_caches[id] = NULL;
+
         css_put(&memcg->css);
 }