From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-la0-f51.google.com (mail-la0-f51.google.com [209.85.215.51]) by kanga.kvack.org (Postfix) with ESMTP id 115316B0044 for ; Mon, 16 Dec 2013 07:17:26 -0500 (EST) Received: by mail-la0-f51.google.com with SMTP id ec20so2592738lab.24 for ; Mon, 16 Dec 2013 04:17:26 -0800 (PST) Received: from relay.parallels.com (relay.parallels.com. [195.214.232.42]) by mx.google.com with ESMTPS id 9si5339405lal.162.2013.12.16.04.17.26 for (version=TLSv1 cipher=RC4-SHA bits=128/128); Mon, 16 Dec 2013 04:17:26 -0800 (PST) From: Vladimir Davydov Subject: [PATCH v14 01/18] memcg: make cache index determination more robust Date: Mon, 16 Dec 2013 16:16:50 +0400 Message-ID: In-Reply-To: References: MIME-Version: 1.0 Content-Type: text/plain Sender: owner-linux-mm@kvack.org List-ID: To: dchinner@redhat.com, mhocko@suse.cz, hannes@cmpxchg.org, akpm@linux-foundation.org Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, cgroups@vger.kernel.org, devel@openvz.org, glommer@openvz.org, glommer@gmail.com, Balbir Singh , KAMEZAWA Hiroyuki From: Glauber Costa I caught myself doing something like the following outside memcg core: memcg_id = -1; if (memcg && memcg_kmem_is_active(memcg)) memcg_id = memcg_cache_id(memcg); to be able to handle all possible memcgs in a sane manner. In particular, the root cache will have kmemcg_id = -1 (just because we don't call memcg_kmem_init to the root cache since it is not limitable). We have always coped with that by making sure we sanitize which cache is passed to memcg_cache_id. Although this example is given for root, what we really need to know is whether or not a cache is kmem active. But outside the memcg core testing for root, for instance, is not trivial since we don't export mem_cgroup_is_root. I ended up realizing that this tests really belong inside memcg_cache_id. This patch moves a similar but stronger test inside memcg_cache_id and make sure it always return a meaningful value. Signed-off-by: Glauber Costa Signed-off-by: Vladimir Davydov Cc: Michal Hocko Cc: Johannes Weiner Cc: Balbir Singh Cc: KAMEZAWA Hiroyuki --- mm/memcontrol.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index bf5e894..3408852 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -3076,7 +3076,9 @@ void memcg_cache_list_add(struct mem_cgroup *memcg, struct kmem_cache *cachep) */ int memcg_cache_id(struct mem_cgroup *memcg) { - return memcg ? memcg->kmemcg_id : -1; + if (!memcg || !memcg_can_account_kmem(memcg)) + return -1; + return memcg->kmemcg_id; } /* -- 1.7.10.4 -- 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