diff options
| -rw-r--r-- | mm/memcontrol.c | 63 |
1 files changed, 33 insertions, 30 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 47b36fea7e1..b8dc8e4cbf6 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); |