memcg, slab: kmem_cache_create_memcg(): fix memleak on fail path

We do not free the cache's memcg_params if __kmem_cache_create fails.
Fix this.

Plus, rename memcg_register_cache() to memcg_alloc_cache_params(),
because it actually does not register the cache anywhere, but simply
initialize kmem_cache::memcg_params.

[akpm@linux-foundation.org: fix build]
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Glauber Costa <glommer@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/memcontrol.h

@@ -497,8 +497,9 @@ void __memcg_kmem_commit_charge(struct page *page,
 void __memcg_kmem_uncharge_pages(struct page *page, int order);
 
 int memcg_cache_id(struct mem_cgroup *memcg);
-int memcg_register_cache(struct mem_cgroup *memcg, struct kmem_cache *s,
+int memcg_alloc_cache_params(struct mem_cgroup *memcg, struct kmem_cache *s,
 			     struct kmem_cache *root_cache);
+void memcg_free_cache_params(struct kmem_cache *s);
 void memcg_release_cache(struct kmem_cache *cachep);
 void memcg_cache_list_add(struct mem_cgroup *memcg, struct kmem_cache *cachep);
 
@@ -640,13 +641,16 @@ static inline int memcg_cache_id(struct mem_cgroup *memcg)
 	return -1;
 }
 
-static inline int
-memcg_register_cache(struct mem_cgroup *memcg, struct kmem_cache *s,
-		     struct kmem_cache *root_cache)
+static inline int memcg_alloc_cache_params(struct mem_cgroup *memcg,
+		struct kmem_cache *s, struct kmem_cache *root_cache)
 {
 	return 0;
 }
 
+static inline void memcg_free_cache_params(struct kmem_cache *s)
+{
+}
+
 static inline void memcg_release_cache(struct kmem_cache *cachep)
 {
 }

mm/memcontrol.c

@@ -3231,7 +3231,7 @@ int memcg_update_cache_size(struct kmem_cache *s, int num_groups)
 	return 0;
 }
 
-int memcg_register_cache(struct mem_cgroup *memcg, struct kmem_cache *s,
+int memcg_alloc_cache_params(struct mem_cgroup *memcg, struct kmem_cache *s,
 			     struct kmem_cache *root_cache)
 {
 	size_t size;
@@ -3260,6 +3260,11 @@ int memcg_register_cache(struct mem_cgroup *memcg, struct kmem_cache *s,
 	return 0;
 }
 
+void memcg_free_cache_params(struct kmem_cache *s)
+{
+	kfree(s->memcg_params);
+}
+
 void memcg_release_cache(struct kmem_cache *s)
 {
 	struct kmem_cache *root;
@@ -3288,7 +3293,7 @@ void memcg_release_cache(struct kmem_cache *s)
 
 	css_put(&memcg->css);
 out:
-	kfree(s->memcg_params);
+	memcg_free_cache_params(s);
 }
 
 /*

mm/slab_common.c

@@ -205,7 +205,7 @@ kmem_cache_create_memcg(struct mem_cgroup *memcg, const char *name, size_t size,
 	if (!s->name)
 		goto out_free_cache;
 
-	err = memcg_register_cache(memcg, s, parent_cache);
+	err = memcg_alloc_cache_params(memcg, s, parent_cache);
 	if (err)
 		goto out_free_cache;
 
@@ -235,6 +235,7 @@ kmem_cache_create_memcg(struct mem_cgroup *memcg, const char *name, size_t size,
 	return s;
 
 out_free_cache:
+	memcg_free_cache_params(s);
 	kfree(s->name);
 	kmem_cache_free(kmem_cache, s);
 	goto out_unlock;