From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f70.google.com (mail-pg0-f70.google.com [74.125.83.70]) by kanga.kvack.org (Postfix) with ESMTP id 86A686B026B for ; Wed, 1 Nov 2017 09:27:09 -0400 (EDT) Received: by mail-pg0-f70.google.com with SMTP id 191so2567314pgd.0 for ; Wed, 01 Nov 2017 06:27:09 -0700 (PDT) Received: from mx2.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id r28si1068159pfk.101.2017.11.01.06.27.02 for (version=TLS1 cipher=AES128-SHA bits=128/128); Wed, 01 Nov 2017 06:27:03 -0700 (PDT) Date: Wed, 1 Nov 2017 14:27:00 +0100 From: Michal Hocko Subject: Re: [PATCH 1/2] mm,oom: Move last second allocation to inside the OOM killer. Message-ID: <20171101132700.qf4exnqezaepjgat@dhcp22.suse.cz> References: <1509537268-4726-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1509537268-4726-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp> Sender: owner-linux-mm@kvack.org List-ID: To: Tetsuo Handa Cc: akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org I would really suggest you to stick with the changelog I have suggested. On Wed 01-11-17 20:54:27, Tetsuo Handa wrote: [...] > diff --git a/mm/oom_kill.c b/mm/oom_kill.c > index 26add8a..118ecdb 100644 > --- a/mm/oom_kill.c > +++ b/mm/oom_kill.c > @@ -870,6 +870,19 @@ static void oom_kill_process(struct oom_control *oc, const char *message) > } > task_unlock(p); > > + /* > + * Try really last second allocation attempt after we selected an OOM > + * victim, for somebody might have managed to free memory while we were > + * selecting an OOM victim which can take quite some time. > + */ > + if (oc->ac) { > + oc->page = alloc_pages_before_oomkill(oc); I would stick the oc->ac check inside alloc_pages_before_oomkill. > + if (oc->page) { > + put_task_struct(p); > + return; > + } > + } > + > if (__ratelimit(&oom_rs)) > dump_header(oc, p); > > @@ -1081,6 +1094,16 @@ bool out_of_memory(struct oom_control *oc) > select_bad_process(oc); > /* Found nothing?!?! Either we hang forever, or we panic. */ > if (!oc->chosen && !is_sysrq_oom(oc) && !is_memcg_oom(oc)) { > + /* > + * Try really last second allocation attempt, for somebody > + * might have managed to free memory while we were trying to > + * find an OOM victim. > + */ > + if (oc->ac) { > + oc->page = alloc_pages_before_oomkill(oc); > + if (oc->page) > + return true; > + } > dump_header(oc, NULL); > panic("Out of memory and no killable processes...\n"); > } Also, is there any strong reason to not do the last allocation after select_bad_process rather than having two call sites? I would understand that if you wanted to catch for_each_thread inside oom_kill_process but you are not doing that. [...] -- 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