From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ed1-f69.google.com (mail-ed1-f69.google.com [209.85.208.69]) by kanga.kvack.org (Postfix) with ESMTP id 965AA6B0003 for ; Mon, 22 Oct 2018 07:12:32 -0400 (EDT) Received: by mail-ed1-f69.google.com with SMTP id c13-v6so24385640ede.6 for ; Mon, 22 Oct 2018 04:12:32 -0700 (PDT) Received: from mx1.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id s6-v6si1713622eda.130.2018.10.22.04.12.31 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 22 Oct 2018 04:12:31 -0700 (PDT) Date: Mon, 22 Oct 2018 13:12:29 +0200 From: Michal Hocko 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> Sender: owner-linux-mm@kvack.org List-ID: To: Tetsuo Handa Cc: linux-mm@kvack.org, Johannes Weiner , David Rientjes , Andrew Morton , LKML 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