memcg: fix mutex not unlocked on memcg_create_kmem_cache fail path

7c094fd6 · Vladimir Davydov <[email protected]> · 2014-01-30 15:46:14 -08:00

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 <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: Glauber Costa <[email protected]>
Acked-by: David Rientjes <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

Commit: 7c094fd698de2f333fa39b6da213f880d40b9bfe
Parents: 46bf16c4

Changes

1 files changed · +3 −4

File	Status	Add	Del	Content
mm/memcontrol.c	modified	+3	−4	View file

mm/memcontrol.c

View file

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 19d5d42..53385cd 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;
 }