From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f198.google.com (mail-pf0-f198.google.com [209.85.192.198]) by kanga.kvack.org (Postfix) with ESMTP id 5D5316B025F for ; Thu, 27 Jul 2017 09:05:09 -0400 (EDT) Received: by mail-pf0-f198.google.com with SMTP id e3so211605006pfc.4 for ; Thu, 27 Jul 2017 06:05:09 -0700 (PDT) Received: from mx0a-00082601.pphosted.com (mx0a-00082601.pphosted.com. [67.231.145.42]) by mx.google.com with ESMTPS id 3si3983157pli.627.2017.07.27.06.05.07 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 27 Jul 2017 06:05:08 -0700 (PDT) From: Roman Gushchin Subject: [PATCH 1/2] mm, memcg: reset memory.low during memcg offlining Date: Thu, 27 Jul 2017 14:04:27 +0100 Message-ID: <20170727130428.28856-1-guro@fb.com> In-Reply-To: <20170726083017.3yzeucmi7lcj46qd@esperanza> References: <20170726083017.3yzeucmi7lcj46qd@esperanza> MIME-Version: 1.0 Content-Type: text/plain Sender: owner-linux-mm@kvack.org List-ID: To: linux-kernel@vger.kernel.org Cc: Roman Gushchin , Vladimir Davydov , Tejun Heo , Johannes Weiner , Michal Hocko , kernel-team@fb.com, cgroups@vger.kernel.org, linux-mm@kvack.org A removed memory cgroup with a defined memory.low and some belonging pagecache has very low chances to be freed. If a cgroup has been removed, there is likely no memory pressure inside the cgroup, and the pagecache is protected from the external pressure by the defined low limit. The cgroup will be freed only after the reclaim of all belonging pages. And it will not happen until there are any reclaimable memory in the system. That means, there is a good chance, that a cold pagecache will reside in the memory for an undefined amount of time, wasting system resources. This problem was fixed earlier by commit fa06235b8eb0 ("cgroup: reset css on destruction"), but it's not a best way to do it, as we can't really reset all limits/counters during cgroup offlining. Signed-off-by: Roman Gushchin Cc: Vladimir Davydov Cc: Tejun Heo Cc: Johannes Weiner Cc: Michal Hocko Cc: kernel-team@fb.com Cc: cgroups@vger.kernel.org Cc: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org --- mm/memcontrol.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index d61133e6af99..7b24210596ea 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -4300,6 +4300,8 @@ static void mem_cgroup_css_offline(struct cgroup_subsys_state *css) } spin_unlock(&memcg->event_list_lock); + memcg->low = 0; + memcg_offline_kmem(memcg); wb_memcg_offline(memcg); -- 2.13.3 -- 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