1 files changed, 33 insertions, 30 deletions

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 47b36fe..b8dc8e4 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3483,7 +3483,6 @@ static void memcg_create_cache_work_func(struct work_struct *w)
 
 /*
  * Enqueue the creation of a per-memcg kmem_cache.
- * Called with rcu_read_lock.
  */
 static void __memcg_create_cache_enqueue(struct mem_cgroup *memcg,
 					 struct kmem_cache *cachep)
@@ -3491,12 +3490,8 @@ static void __memcg_create_cache_enqueue(struct mem_cgroup *memcg,
 	struct create_work *cw;
 
 	cw = kmalloc(sizeof(struct create_work), GFP_NOWAIT);
-	if (cw == NULL)
-		return;
-
-	/* The corresponding put will be done in the workqueue. */
-	if (!css_tryget(&memcg->css)) {
-		kfree(cw);
+	if (cw == NULL) {
+		css_put(&memcg->css);
 		return;
 	}
 
@@ -3552,10 +3547,9 @@ struct kmem_cache *__memcg_kmem_get_cache(struct kmem_cache *cachep,
 
 	rcu_read_lock();
 	memcg = mem_cgroup_from_task(rcu_dereference(current->mm->owner));
-	rcu_read_unlock();
 
 	if (!memcg_can_account_kmem(memcg))
-		return cachep;
+		goto out;
 
 	idx = memcg_cache_id(memcg);
 
@@ -3564,29 +3558,38 @@ struct kmem_cache *__memcg_kmem_get_cache(struct kmem_cache *cachep,
 	 * code updating memcg_caches will issue a write barrier to match this.
 	 */
 	read_barrier_depends();
-	if (unlikely(cachep->memcg_params->memcg_caches[idx] == NULL)) {
-		/*
-		 * If we are in a safe context (can wait, and not in interrupt
-		 * context), we could be be predictable and return right away.
-		 * This would guarantee that the allocation being performed
-		 * already belongs in the new cache.
-		 *
-		 * However, there are some clashes that can arrive from locking.
-		 * For instance, because we acquire the slab_mutex while doing
-		 * kmem_cache_dup, this means no further allocation could happen
-		 * with the slab_mutex held.
-		 *
-		 * Also, because cache creation issue get_online_cpus(), this
-		 * creates a lock chain: memcg_slab_mutex -> cpu_hotplug_mutex,
-		 * that ends up reversed during cpu hotplug. (cpuset allocates
-		 * a bunch of GFP_KERNEL memory during cpuup). Due to all that,
-		 * better to defer everything.
-		 */
-		memcg_create_cache_enqueue(memcg, cachep);
-		return cachep;
+	if (likely(cachep->memcg_params->memcg_caches[idx])) {
+		cachep = cachep->memcg_params->memcg_caches[idx];
+		goto out;
 	}
 
-	return cachep->memcg_params->memcg_caches[idx];
+	/* The corresponding put will be done in the workqueue. */
+	if (!css_tryget(&memcg->css))
+		goto out;
+	rcu_read_unlock();
+
+	/*
+	 * If we are in a safe context (can wait, and not in interrupt
+	 * context), we could be be predictable and return right away.
+	 * This would guarantee that the allocation being performed
+	 * already belongs in the new cache.
+	 *
+	 * However, there are some clashes that can arrive from locking.
+	 * For instance, because we acquire the slab_mutex while doing
+	 * kmem_cache_dup, this means no further allocation could happen
+	 * with the slab_mutex held.
+	 *
+	 * Also, because cache creation issue get_online_cpus(), this
+	 * creates a lock chain: memcg_slab_mutex -> cpu_hotplug_mutex,
+	 * that ends up reversed during cpu hotplug. (cpuset allocates
+	 * a bunch of GFP_KERNEL memory during cpuup). Due to all that,
+	 * better to defer everything.
+	 */
+	memcg_create_cache_enqueue(memcg, cachep);
+	return cachep;
+out:
+	rcu_read_unlock();
+	return cachep;
 }
 EXPORT_SYMBOL(__memcg_kmem_get_cache);