From 7c094fd698de2f333fa39b6da213f880d40b9bfe Mon Sep 17 00:00:00 2001 From: Vladimir Davydov Date: Thu, 30 Jan 2014 15:46:14 -0800 Subject: [PATCH] memcg: fix mutex not unlocked on memcg_create_kmem_cache fail path Commit 842e2873697e ("memcg: get rid of kmem_cache_dup()") introduced a mutex for memcg_create_kmem_cache() to protect the tmp_name buffer that holds the memcg name. It failed to unlock the mutex if this buffer could not be allocated. This patch fixes the issue by appropriately unlocking the mutex if the allocation fails. Signed-off-by: Vladimir Davydov Cc: Michal Hocko Cc: Johannes Weiner Cc: Glauber Costa Acked-by: David Rientjes Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/memcontrol.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 19d5d4274e22..53385cd4e6f0 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -3400,7 +3400,7 @@ void mem_cgroup_destroy_cache(struct kmem_cache *cachep) static struct kmem_cache *memcg_create_kmem_cache(struct mem_cgroup *memcg, struct kmem_cache *s) { - struct kmem_cache *new; + struct kmem_cache *new = NULL; static char *tmp_name = NULL; static DEFINE_MUTEX(mutex); /* protects tmp_name */ @@ -3416,7 +3416,7 @@ static struct kmem_cache *memcg_create_kmem_cache(struct mem_cgroup *memcg, if (!tmp_name) { tmp_name = kmalloc(PATH_MAX, GFP_KERNEL); if (!tmp_name) - return NULL; + goto out; } rcu_read_lock(); @@ -3426,12 +3426,11 @@ static struct kmem_cache *memcg_create_kmem_cache(struct mem_cgroup *memcg, new = kmem_cache_create_memcg(memcg, tmp_name, s->object_size, s->align, (s->flags & ~SLAB_PANIC), s->ctor, s); - if (new) new->allocflags |= __GFP_KMEMCG; else new = s; - +out: mutex_unlock(&mutex); return new; }