From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757352AbcHBS3Z (ORCPT ); Tue, 2 Aug 2016 14:29:25 -0400 Received: from gum.cmpxchg.org ([85.214.110.215]:55946 "EHLO gum.cmpxchg.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757320AbcHBS2V (ORCPT ); Tue, 2 Aug 2016 14:28:21 -0400 Date: Tue, 2 Aug 2016 13:21:37 -0400 From: Johannes Weiner To: Vladimir Davydov Cc: Andrew Morton , stable@vger.kernel.org, Michal Hocko , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 1/3] mm: memcontrol: fix swap counter leak on swapout from offline cgroup Message-ID: <20160802172137.GA6637@cmpxchg.org> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.6.2 (2016-07-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Aug 02, 2016 at 06:00:48PM +0300, Vladimir Davydov wrote: > An offline memory cgroup might have anonymous memory or shmem left > charged to it and no swap. Since only swap entries pin the id of an > offline cgroup, such a cgroup will have no id and so an attempt to > swapout its anon/shmem will not store memory cgroup info in the swap > cgroup map. As a result, memcg->swap or memcg->memsw will never get > uncharged from it and any of its ascendants. > > Fix this by always charging swapout to the first ancestor cgroup that > hasn't released its id yet. > > Fixes: 73f576c04b941 ("mm: memcontrol: fix cgroup creation failure after many small jobs") > Signed-off-by: Vladimir Davydov > Cc: [3.19+] Acked-by: Johannes Weiner