Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751900AbdG0Of2 (ORCPT ); Thu, 27 Jul 2017 10:35:28 -0400 Received: from gum.cmpxchg.org ([85.214.110.215]:52128 "EHLO gum.cmpxchg.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751769AbdG0Of1 (ORCPT ); Thu, 27 Jul 2017 10:35:27 -0400 Date: Thu, 27 Jul 2017 10:35:21 -0400 From: Johannes Weiner To: Roman Gushchin Cc: linux-kernel@vger.kernel.org, Vladimir Davydov , Tejun Heo , Michal Hocko , kernel-team@fb.com, cgroups@vger.kernel.org, linux-mm@kvack.org, Andrew Morton Subject: Re: [PATCH 1/2] mm, memcg: reset memory.low during memcg offlining Message-ID: <20170727143521.GB19738@cmpxchg.org> References: <20170726083017.3yzeucmi7lcj46qd@esperanza> <20170727130428.28856-1-guro@fb.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170727130428.28856-1-guro@fb.com> User-Agent: Mutt/1.8.3 (2017-05-23) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1303 Lines: 31 CC Andrew - can you route these through the -mm tree please? On Thu, Jul 27, 2017 at 02:04:27PM +0100, Roman Gushchin wrote: > 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 Acked-by: Johannes Weiner