From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751929AbdHGOEN (ORCPT ); Mon, 7 Aug 2017 10:04:13 -0400 Received: from mx2.suse.de ([195.135.220.15]:44839 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751789AbdHGOEM (ORCPT ); Mon, 7 Aug 2017 10:04:12 -0400 Date: Mon, 7 Aug 2017 16:04:09 +0200 From: Michal Hocko To: Tetsuo Handa Cc: akpm@linux-foundation.org, andrea@kernel.org, kirill@shutemov.name, oleg@redhat.com, wenwei.tww@alibaba-inc.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 0/2] mm, oom: fix oom_reaper fallouts Message-ID: <20170807140409.GJ32434@dhcp22.suse.cz> References: <20170807113839.16695-1-mhocko@kernel.org> <201708072228.FAJ09347.tOOVOFFQJSHMFL@I-love.SAKURA.ne.jp> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <201708072228.FAJ09347.tOOVOFFQJSHMFL@I-love.SAKURA.ne.jp> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon 07-08-17 22:28:27, Tetsuo Handa wrote: > Michal Hocko wrote: > > Hi, > > there are two issues this patch series attempts to fix. First one is > > something that has been broken since MMF_UNSTABLE flag introduction > > and I guess we should backport it stable trees (patch 1). The other > > issue has been brought up by Wenwei Tao and Tetsuo Handa has created > > a test case to trigger it very reliably. I am not yet sure this is a > > stable material because the test case is rather artificial. If there is > > a demand for the stable backport I will prepare it, of course, though. > > > > I hope I've done the second patch correctly but I would definitely > > appreciate some more eyes on it. Hence CCing Andrea and Kirill. My > > previous attempt with some more context was posted here > > http://lkml.kernel.org/r/20170803135902.31977-1-mhocko@kernel.org > > > > My testing didn't show anything unusual with these two applied on top of > > the mmotm tree. > > I really don't like your likely/unlikely speculation. Have you seen any non artificial workload triggering this? Look, I am not going to argue about how likely this is or not. I've said I am willing to do backports if there is a demand but please do realize that this is not a trivial change to backport pre 4.9 kernels would require MMF_UNSTABLE to be backported as well. This all can be discussed after the merge so can we focus on the review now rather than any distractions? Also please note that while writing zeros is certainly bad any integrity assumptions are basically off when an application gets killed unexpectedly while performing an IO. -- Michal Hocko SUSE Labs From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr0-f198.google.com (mail-wr0-f198.google.com [209.85.128.198]) by kanga.kvack.org (Postfix) with ESMTP id 84A946B025F for ; Mon, 7 Aug 2017 10:04:14 -0400 (EDT) Received: by mail-wr0-f198.google.com with SMTP id g28so736718wrg.3 for ; Mon, 07 Aug 2017 07:04:14 -0700 (PDT) Received: from mx1.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id 125si7496750wmv.33.2017.08.07.07.04.13 for (version=TLS1 cipher=AES128-SHA bits=128/128); Mon, 07 Aug 2017 07:04:13 -0700 (PDT) Date: Mon, 7 Aug 2017 16:04:09 +0200 From: Michal Hocko Subject: Re: [PATCH 0/2] mm, oom: fix oom_reaper fallouts Message-ID: <20170807140409.GJ32434@dhcp22.suse.cz> References: <20170807113839.16695-1-mhocko@kernel.org> <201708072228.FAJ09347.tOOVOFFQJSHMFL@I-love.SAKURA.ne.jp> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <201708072228.FAJ09347.tOOVOFFQJSHMFL@I-love.SAKURA.ne.jp> Sender: owner-linux-mm@kvack.org List-ID: To: Tetsuo Handa Cc: akpm@linux-foundation.org, andrea@kernel.org, kirill@shutemov.name, oleg@redhat.com, wenwei.tww@alibaba-inc.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org On Mon 07-08-17 22:28:27, Tetsuo Handa wrote: > Michal Hocko wrote: > > Hi, > > there are two issues this patch series attempts to fix. First one is > > something that has been broken since MMF_UNSTABLE flag introduction > > and I guess we should backport it stable trees (patch 1). The other > > issue has been brought up by Wenwei Tao and Tetsuo Handa has created > > a test case to trigger it very reliably. I am not yet sure this is a > > stable material because the test case is rather artificial. If there is > > a demand for the stable backport I will prepare it, of course, though. > > > > I hope I've done the second patch correctly but I would definitely > > appreciate some more eyes on it. Hence CCing Andrea and Kirill. My > > previous attempt with some more context was posted here > > http://lkml.kernel.org/r/20170803135902.31977-1-mhocko@kernel.org > > > > My testing didn't show anything unusual with these two applied on top of > > the mmotm tree. > > I really don't like your likely/unlikely speculation. Have you seen any non artificial workload triggering this? Look, I am not going to argue about how likely this is or not. I've said I am willing to do backports if there is a demand but please do realize that this is not a trivial change to backport pre 4.9 kernels would require MMF_UNSTABLE to be backported as well. This all can be discussed after the merge so can we focus on the review now rather than any distractions? Also please note that while writing zeros is certainly bad any integrity assumptions are basically off when an application gets killed unexpectedly while performing an IO. -- Michal Hocko SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org