memcg: fix mutex not unlocked on memcg_create_kmem_cache fail path (7c094fd6) · Commits · 戴 / test

Commit ("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>

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;
		}

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