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Commit 7c094fd6 authored by Vladimir Davydov's avatar Vladimir Davydov Committed by Linus Torvalds
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memcg: fix mutex not unlocked on memcg_create_kmem_cache fail path 



Commit 842e2873 ("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: default avatarVladimir Davydov <vdavydov@parallels.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Glauber Costa <glommer@parallels.com>
Acked-by: default avatarDavid Rientjes <rientjes@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 46bf16c4

mm/memcontrol.c

+3 −4
Original line number Diff line number Diff line
@@ -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;

}