From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754029Ab3KYMIt (ORCPT ); Mon, 25 Nov 2013 07:08:49 -0500 Received: from relay.parallels.com ([195.214.232.42]:53508 "EHLO relay.parallels.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753923Ab3KYMHz (ORCPT ); Mon, 25 Nov 2013 07:07:55 -0500 From: Vladimir Davydov To: , CC: , , , , Subject: [PATCH v11 15/15] memcg: flush memcg items upon memcg destruction Date: Mon, 25 Nov 2013 16:07:48 +0400 Message-ID: <999eb4e30ed5af993595ce217b0aa76029d40e4b.1385377616.git.vdavydov@parallels.com> X-Mailer: git-send-email 1.7.10.4 In-Reply-To: References: MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.30.24.145] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Glauber Costa When a memcg is destroyed, it won't be imediately released until all objects are gone. This means that if a memcg is restarted with the very same workload - a very common case, the objects already cached won't be billed to the new memcg. This is mostly undesirable since a container can exploit this by restarting itself every time it reaches its limit, and then coming up again with a fresh new limit. Since now we have targeted reclaim, I sustain that we should assume that a memcg that is destroyed should be flushed away. It makes perfect sense if we assume that a memcg that goes away most likely indicates an isolated workload that is terminated. Signed-off-by: Glauber Costa Cc: Mel Gorman Cc: Johannes Weiner Cc: Michal Hocko Cc: Hugh Dickins Cc: Kamezawa Hiroyuki --- mm/memcontrol.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 3533d33..471b544 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -6453,12 +6453,29 @@ static void memcg_destroy_kmem(struct mem_cgroup *memcg) static void kmem_cgroup_css_offline(struct mem_cgroup *memcg) { + int ret; if (!memcg_kmem_is_active(memcg)) return; cancel_work_sync(&memcg->kmemcg_shrink_work); /* + * When a memcg is destroyed, it won't be imediately released until all + * objects are gone. This means that if a memcg is restarted with the + * very same workload - a very common case, the objects already cached + * won't be billed to the new memcg. This is mostly undesirable since a + * container can exploit this by restarting itself every time it + * reaches its limit, and then coming up again with a fresh new limit. + * + * Therefore a memcg that is destroyed should be flushed away. It makes + * perfect sense if we assume that a memcg that goes away indicates an + * isolated workload that is terminated. + */ + do { + ret = try_to_free_mem_cgroup_kmem(memcg, GFP_KERNEL); + } while (ret); + + /* * kmem charges can outlive the cgroup. In the case of slab * pages, for instance, a page contain objects from various * processes. As we prevent from taking a reference for every -- 1.7.10.4