1 files changed, 54 insertions, 36 deletions

diff --git a/mm/slab_common.c b/mm/slab_common.c
index 0b7bb399b0e..8e40321da09 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -171,13 +171,26 @@ kmem_cache_create_memcg(struct mem_cgroup *memcg, const char *name, size_t size,
 			struct kmem_cache *parent_cache)
 {
 	struct kmem_cache *s = NULL;
-	int err = 0;
+	int err;
 
 	get_online_cpus();
 	mutex_lock(&slab_mutex);
 
-	if (!kmem_cache_sanity_check(memcg, name, size) == 0)
-		goto out_locked;
+	err = kmem_cache_sanity_check(memcg, name, size);
+	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
@@ -189,45 +202,45 @@ kmem_cache_create_memcg(struct mem_cgroup *memcg, const char *name, size_t size,
 
 	s = __kmem_cache_alias(memcg, name, size, align, flags, ctor);
 	if (s)
-		goto out_locked;
+		goto out_unlock;
 
+	err = -ENOMEM;
 	s = kmem_cache_zalloc(kmem_cache, GFP_KERNEL);
-	if (s) {
-		s->object_size = s->size = size;
-		s->align = calculate_alignment(flags, align, size);
-		s->ctor = ctor;
+	if (!s)
+		goto out_unlock;
 
-		if (memcg_register_cache(memcg, s, parent_cache)) {
-			kmem_cache_free(kmem_cache, s);
-			err = -ENOMEM;
-			goto out_locked;
-		}
+	s->object_size = s->size = size;
+	s->align = calculate_alignment(flags, align, size);
+	s->ctor = ctor;
 
-		s->name = kstrdup(name, GFP_KERNEL);
-		if (!s->name) {
-			kmem_cache_free(kmem_cache, s);
-			err = -ENOMEM;
-			goto out_locked;
-		}
+	s->name = kstrdup(name, GFP_KERNEL);
+	if (!s->name)
+		goto out_free_cache;
 
-		err = __kmem_cache_create(s, flags);
-		if (!err) {
-			s->refcount = 1;
-			list_add(&s->list, &slab_caches);
-			memcg_cache_list_add(memcg, s);
-		} else {
-			kfree(s->name);
-			kmem_cache_free(kmem_cache, s);
-		}
-	} else
-		err = -ENOMEM;
+	err = memcg_alloc_cache_params(memcg, s, parent_cache);
+	if (err)
+		goto out_free_cache;
+
+	err = __kmem_cache_create(s, flags);
+	if (err)
+		goto out_free_cache;
 
-out_locked:
+	s->refcount = 1;
+	list_add(&s->list, &slab_caches);
+	memcg_register_cache(s);
+
+out_unlock:
 	mutex_unlock(&slab_mutex);
 	put_online_cpus();
 
-	if (err) {
-
+	/*
+	 * There is no point in flooding logs with warnings or especially
+	 * crashing the system if we fail to create a cache for a memcg. In
+	 * this case we will be accounting the memcg allocation to the root
+	 * cgroup until we succeed to create its own cache, but it isn't that
+	 * critical.
+	 */
+	if (err && !memcg) {
 		if (flags & SLAB_PANIC)
 			panic("kmem_cache_create: Failed to create slab '%s'. Error %d\n",
 				name, err);
@@ -236,11 +249,15 @@ out_locked:
 				name, err);
 			dump_stack();
 		}
-
 		return NULL;
 	}
-
 	return s;
+
+out_free_cache:
+	memcg_free_cache_params(s);
+	kfree(s->name);
+	kmem_cache_free(kmem_cache, s);
+	goto out_unlock;
 }
 
 struct kmem_cache *
@@ -263,11 +280,12 @@ void kmem_cache_destroy(struct kmem_cache *s)
 		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_release_cache(s);
+			memcg_free_cache_params(s);
 			kfree(s->name);
 			kmem_cache_free(kmem_cache, s);
 		} else {