diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 014a4f1..d2da65c 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3264,6 +3264,12 @@
 	if (is_root_cache(s))
 		return;
 
+	/*
+	 * Holding the slab_mutex assures nobody will touch the memcg_caches
+	 * array while we are modifying it.
+	 */
+	lockdep_assert_held(&slab_mutex);
+
 	root = s->memcg_params->root_cache;
 	memcg = s->memcg_params->memcg;
 	id = memcg_cache_id(memcg);
@@ -3283,6 +3289,7 @@
 	 * before adding it to the memcg_slab_caches list, otherwise we can
 	 * fail to convert memcg_params_to_cache() while traversing the list.
 	 */
+	VM_BUG_ON(root->memcg_params->memcg_caches[id]);
 	root->memcg_params->memcg_caches[id] = s;
 
 	mutex_lock(&memcg->slab_caches_mutex);
@@ -3299,6 +3306,12 @@
 	if (is_root_cache(s))
 		return;
 
+	/*
+	 * Holding the slab_mutex assures nobody will touch the memcg_caches
+	 * array while we are modifying it.
+	 */
+	lockdep_assert_held(&slab_mutex);
+
 	root = s->memcg_params->root_cache;
 	memcg = s->memcg_params->memcg;
 	id = memcg_cache_id(memcg);
@@ -3312,6 +3325,7 @@
 	 * after removing it from the memcg_slab_caches list, otherwise we can
 	 * fail to convert memcg_params_to_cache() while traversing the list.
 	 */
+	VM_BUG_ON(!root->memcg_params->memcg_caches[id]);
 	root->memcg_params->memcg_caches[id] = NULL;
 
 	css_put(&memcg->css);
@@ -3464,22 +3478,13 @@
 						  struct kmem_cache *cachep)
 {
 	struct kmem_cache *new_cachep;
-	int idx;
 
 	BUG_ON(!memcg_can_account_kmem(memcg));
 
-	idx = memcg_cache_id(memcg);
-
 	mutex_lock(&memcg_cache_mutex);
-	new_cachep = cache_from_memcg_idx(cachep, idx);
-	if (new_cachep)
-		goto out;
-
 	new_cachep = kmem_cache_dup(memcg, cachep);
 	if (new_cachep == NULL)
 		new_cachep = cachep;
-
-out:
 	mutex_unlock(&memcg_cache_mutex);
 	return new_cachep;
 }
diff --git a/mm/slab_common.c b/mm/slab_common.c
index db24ec4..f34707e 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -180,6 +180,18 @@
 	if (err)
 		goto out_unlock;
 
+	if (memcg) {
+		/*
+		 * Since per-memcg caches are created asynchronously on first
+		 * allocation (see memcg_kmem_get_cache()), several threads can
+		 * try to create the same cache, but only one of them may
+		 * succeed. Therefore if we get here and see the cache has
+		 * already been created, we silently return NULL.
+		 */
+		if (cache_from_memcg_idx(parent_cache, memcg_cache_id(memcg)))
+			goto out_unlock;
+	}
+
 	/*
 	 * Some allocators will constraint the set of valid flags to a subset
 	 * of all flags. We expect them to define CACHE_CREATE_MASK in this
@@ -261,11 +273,11 @@
 		list_del(&s->list);
 
 		if (!__kmem_cache_shutdown(s)) {
+			memcg_unregister_cache(s);
 			mutex_unlock(&slab_mutex);
 			if (s->flags & SLAB_DESTROY_BY_RCU)
 				rcu_barrier();
 
-			memcg_unregister_cache(s);
 			memcg_free_cache_params(s);
 			kfree(s->name);
 			kmem_cache_free(kmem_cache, s);