From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx110.postini.com [74.125.245.110]) by kanga.kvack.org (Postfix) with SMTP id 23EB26B0039 for ; Thu, 13 Jun 2013 21:58:48 -0400 (EDT) Message-ID: <51BA77DD.1000103@huawei.com> Date: Fri, 14 Jun 2013 09:54:37 +0800 From: Li Zefan MIME-Version: 1.0 Subject: [PATCH v4 4/9] memcg: don't use mem_cgroup_get() when creating a kmemcg cache References: <51BA7794.2000305@huawei.com> In-Reply-To: <51BA7794.2000305@huawei.com> Content-Type: text/plain; charset="GB2312" Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: Tejun Heo , Glauber Costa , KAMEZAWA Hiroyuki , Johannes Weiner , LKML , Cgroups , linux-mm@kvack.org, Michal Hocko Use css_get()/css_put() instead of mem_cgroup_get()/mem_cgroup_put(). There are two things being done in the current code: First, we acquired a css_ref to make sure that the underlying cgroup would not go away. That is a short lived reference, and it is put as soon as the cache is created. At this point, we acquire a long-lived per-cache memcg reference count to guarantee that the memcg will still be alive. so it is: enqueue: css_get create : memcg_get, css_put destroy: memcg_put So we only need to get rid of the memcg_get, change the memcg_put to css_put, and get rid of the now extra css_put. (This changelog is mostly written by Glauber) Signed-off-by: Li Zefan Acked-by: Michal Hocko Acked-by: KAMEZAWA Hiroyuki --- mm/memcontrol.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index a8e8d2a..466c595 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -3252,7 +3252,7 @@ void memcg_release_cache(struct kmem_cache *s) list_del(&s->memcg_params->list); mutex_unlock(&memcg->slab_caches_mutex); - mem_cgroup_put(memcg); + css_put(&memcg->css); out: kfree(s->memcg_params); } @@ -3412,16 +3412,18 @@ static struct kmem_cache *memcg_create_kmem_cache(struct mem_cgroup *memcg, mutex_lock(&memcg_cache_mutex); new_cachep = cachep->memcg_params->memcg_caches[idx]; - if (new_cachep) + if (new_cachep) { + css_put(&memcg->css); goto out; + } new_cachep = kmem_cache_dup(memcg, cachep); if (new_cachep == NULL) { new_cachep = cachep; + css_put(&memcg->css); goto out; } - mem_cgroup_get(memcg); atomic_set(&new_cachep->memcg_params->nr_pages , 0); cachep->memcg_params->memcg_caches[idx] = new_cachep; @@ -3509,8 +3511,6 @@ static void memcg_create_cache_work_func(struct work_struct *w) cw = container_of(w, struct create_work, work); memcg_create_kmem_cache(cw->memcg, cw->cachep); - /* Drop the reference gotten when we enqueued. */ - css_put(&cw->memcg->css); kfree(cw); } -- 1.8.0.2 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org