From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755043AbcHVK45 (ORCPT ); Mon, 22 Aug 2016 06:56:57 -0400 Received: from mail-wm0-f68.google.com ([74.125.82.68]:35993 "EHLO mail-wm0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755021AbcHVK4z (ORCPT ); Mon, 22 Aug 2016 06:56:55 -0400 Date: Mon, 22 Aug 2016 12:56:53 +0200 From: Michal Hocko To: Markus Trippelsdorf Cc: Andrew Morton , greg@suse.cz, Linus Torvalds , Arkadiusz Miskiewicz , Ralf-Peter Rohbeck , Jiri Slaby , Olaf Hering , Vlastimil Babka , Joonsoo Kim , linux-mm@kvack.org, LKML Subject: Re: OOM detection regressions since 4.7 Message-ID: <20160822105653.GI13596@dhcp22.suse.cz> References: <20160822093249.GA14916@dhcp22.suse.cz> <20160822101614.GA314@x4> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160822101614.GA314@x4> User-Agent: Mutt/1.6.0 (2016-04-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon 22-08-16 12:16:14, Markus Trippelsdorf wrote: > On 2016.08.22 at 11:32 +0200, Michal Hocko wrote: > > there have been multiple reports [1][2][3][4][5] about pre-mature OOM > > killer invocations since 4.7 which contains oom detection rework. All of > > them were for order-2 (kernel stack) alloaction requests failing because > > of a high fragmentation and compaction failing to make any forward > > progress. While investigating this we have found out that the compaction > > just gives up too early. Vlastimil has been working on compaction > > improvement for quite some time and his series [6] is already sitting > > in mmotm tree. This already helps a lot because it drops some heuristics > > which are more aimed at lower latencies for high orders rather than > > reliability. Joonsoo has then identified further problem with too many > > blocks being marked as unmovable [7] and Vlastimil has prepared a patch > > on top of his series [8] which is also in the mmotm tree now. > > > > That being said, the regression is real and should be fixed for 4.7 > > stable users. [6][8] was reported to help and ooms are no longer > > reproducible. I know we are quite late (rc3) in 4.8 but I would vote > > for mergeing those patches and have them in 4.8. For 4.7 I would go > > with a partial revert of the detection rework for high order requests > > (see patch below). This patch is really trivial. If those compaction > > improvements are just too large for 4.8 then we can use the same patch > > as for 4.7 stable for now and revert it in 4.9 after compaction changes > > are merged. > > > > Thoughts? > > > > [1] http://lkml.kernel.org/r/20160731051121.GB307@x4 > > For the report [1] above: > > markus@x4 linux % cat .config | grep CONFIG_COMPACTION > # CONFIG_COMPACTION is not set Hmm, without compaction and a heavy fragmentation then I am afraid we cannot really do much. What is the reason to disable compaction in the first place? -- Michal Hocko SUSE Labs