From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.5 required=3.0 tests=MAILING_LIST_MULTI,SPF_PASS, USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2A9ABC004D3 for ; Mon, 22 Oct 2018 11:12:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E306C20658 for ; Mon, 22 Oct 2018 11:12:33 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E306C20658 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728364AbeJVTai (ORCPT ); Mon, 22 Oct 2018 15:30:38 -0400 Received: from mx2.suse.de ([195.135.220.15]:55880 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727700AbeJVTai (ORCPT ); Mon, 22 Oct 2018 15:30:38 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay1.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 6D17BAE8F; Mon, 22 Oct 2018 11:12:30 +0000 (UTC) Date: Mon, 22 Oct 2018 13:12:29 +0200 From: Michal Hocko To: Tetsuo Handa Cc: linux-mm@kvack.org, Johannes Weiner , David Rientjes , Andrew Morton , LKML Subject: Re: [RFC PATCH 1/2] mm, oom: marks all killed tasks as oom victims Message-ID: <20181022111229.GZ18839@dhcp22.suse.cz> References: <20181022071323.9550-1-mhocko@kernel.org> <20181022071323.9550-2-mhocko@kernel.org> <201810220758.w9M7wojE016890@www262.sakura.ne.jp> <20181022084842.GW18839@dhcp22.suse.cz> <20181022104341.GY18839@dhcp22.suse.cz> <93f99371-cff8-fc31-a594-eecdff299f16@i-love.sakura.ne.jp> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <93f99371-cff8-fc31-a594-eecdff299f16@i-love.sakura.ne.jp> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon 22-10-18 19:56:49, Tetsuo Handa wrote: > On 2018/10/22 19:43, Michal Hocko wrote: > > On Mon 22-10-18 18:42:30, Tetsuo Handa wrote: > >> On 2018/10/22 17:48, Michal Hocko wrote: > >>> On Mon 22-10-18 16:58:50, Tetsuo Handa wrote: > >>>> Michal Hocko wrote: > >>>>> --- a/mm/oom_kill.c > >>>>> +++ b/mm/oom_kill.c > >>>>> @@ -898,6 +898,7 @@ static void __oom_kill_process(struct task_struct *victim) > >>>>> if (unlikely(p->flags & PF_KTHREAD)) > >>>>> continue; > >>>>> do_send_sig_info(SIGKILL, SEND_SIG_FORCED, p, PIDTYPE_TGID); > >>>>> + mark_oom_victim(p); > >>>>> } > >>>>> rcu_read_unlock(); > >>>>> > >>>>> -- > >>>> > >>>> Wrong. Either > >>> > >>> You are right. The mm might go away between process_shares_mm and here. > >>> While your find_lock_task_mm would be correct I believe we can do better > >>> by using the existing mm that we already have. I will make it a separate > >>> patch to clarity. > >> > >> Still wrong. p->mm == NULL means that we are too late to set TIF_MEMDIE > >> on that thread. Passing non-NULL mm to mark_oom_victim() won't help. > > > > Why would it be too late? Or in other words why would this be harmful? > > > > Setting TIF_MEMDIE after exit_mm() completed is too late. You are right and I am obviously dense today. I will go with find_lock_task_mm for now and push the "get rid of TIF_MEMDIE" up in the todo list. I hope I will get to it some day. -- Michal Hocko SUSE Labs