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memcg: fix mutex not unlocked on memcg_create_kmem_cache fail path 

Commit 842e287369 ("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 <vdavydov@parallels.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Glauber Costa <glommer@parallels.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Vladimir Davydov 2014-01-30 15:46:14 -08:00 committed by Linus Torvalds
parent 46bf16c44b
commit 7c094fd698
1 changed files with 3 additions and 4 deletions
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7
mm/memcontrol.c
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@ -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;
}