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-rw-r--r--mm/memcontrol.c63
1 files changed, 33 insertions, 30 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 47b36fea7e1f..b8dc8e4cbf6a 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);