From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-oi0-f72.google.com (mail-oi0-f72.google.com [209.85.218.72]) by kanga.kvack.org (Postfix) with ESMTP id 634B36B0003 for ; Tue, 14 Aug 2018 20:36:50 -0400 (EDT) Received: by mail-oi0-f72.google.com with SMTP id b8-v6so21845667oib.4 for ; Tue, 14 Aug 2018 17:36:50 -0700 (PDT) Received: from mx0a-00082601.pphosted.com (mx0a-00082601.pphosted.com. [67.231.145.42]) by mx.google.com with ESMTPS id l77-v6si14731910oig.48.2018.08.14.17.36.49 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 14 Aug 2018 17:36:49 -0700 (PDT) From: Roman Gushchin Subject: [RFC PATCH 2/2] mm: drain memcg stocks on css offlining Date: Tue, 14 Aug 2018 17:36:20 -0700 Message-ID: <20180815003620.15678-2-guro@fb.com> In-Reply-To: <20180815003620.15678-1-guro@fb.com> References: <20180815003620.15678-1-guro@fb.com> MIME-Version: 1.0 Content-Type: text/plain Sender: owner-linux-mm@kvack.org List-ID: To: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, kernel-team@fb.com, Roman Gushchin , Johannes Weiner , Michal Hocko , Konstantin Khlebnikov , Tejun Heo Memcg charge is batched using per-cpu stocks, so an offline memcg can be pinned by a cached charge up to a moment, when a process belonging to some other cgroup will charge some memory on the same cpu. In other words, cached charges can prevent a memory cgroup from being reclaimed for some time, without any clear need. Let's optimize it by explicit draining of all stocks on css offlining. As draining is performed asynchronously, and is skipped if any parallel draining is happening, it's cheap. Signed-off-by: Roman Gushchin Cc: Johannes Weiner Cc: Michal Hocko Cc: Konstantin Khlebnikov Cc: Tejun Heo --- mm/memcontrol.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 4e3c1315b1de..cfb64b5b9957 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -4575,6 +4575,8 @@ static void mem_cgroup_css_offline(struct cgroup_subsys_state *css) memcg_offline_kmem(memcg); wb_memcg_offline(memcg); + drain_all_stock(memcg); + mem_cgroup_id_put(memcg); } -- 2.14.4