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=-7.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 69039C43387 for ; Fri, 11 Jan 2019 16:45:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 33B0F20657 for ; Fri, 11 Jan 2019 16:45:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1547225140; bh=1zuk0lRJhxt1KtIcuSnHD65qwzMIWTZpvezv6qtKS9o=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=1rwsVtSvepf+YcHUZI3hviai5QXk888kVuDTel7j1a6S4K25SMjfk+52mlS/I04cl GlnBZqG8mDUXqiN7eAWFzkRz7qu/HrqU37r99B7lNBCOjTfIc7sNw1HTaxnmSUPilc nu5yG32tWa2BgHBqG91pkQl7PyvU3AupAOI/KTh0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732291AbfAKQpj (ORCPT ); Fri, 11 Jan 2019 11:45:39 -0500 Received: from mx2.suse.de ([195.135.220.15]:44262 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728266AbfAKQpi (ORCPT ); Fri, 11 Jan 2019 11:45:38 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id B4B4FAE26; Fri, 11 Jan 2019 16:45:37 +0000 (UTC) Date: Fri, 11 Jan 2019 17:45:36 +0100 From: Michal Hocko To: Tetsuo Handa Cc: Andrew Morton , linux-mm@kvack.org, Johannes Weiner , LKML Subject: Re: [PATCH 0/2] oom, memcg: do not report racy no-eligible OOM Message-ID: <20190111164536.GJ14956@dhcp22.suse.cz> References: <20190109120212.GT31793@dhcp22.suse.cz> <201901102359.x0ANxIbn020225@www262.sakura.ne.jp> <20190111113354.GD14956@dhcp22.suse.cz> <0d67b389-91e2-18ab-b596-39361b895c89@i-love.sakura.ne.jp> <20190111133401.GA6997@dhcp22.suse.cz> <20190111150703.GI14956@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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 Sat 12-01-19 00:37:05, Tetsuo Handa wrote: > On 2019/01/12 0:07, Michal Hocko wrote: > > On Fri 11-01-19 23:31:18, Tetsuo Handa wrote: > >> The OOM killer invoked by [ T9694] called printk() but didn't kill anything. > >> Instead, SIGINT from Ctrl-C killed all thread groups sharing current->mm. > > > > I still do not get it. Those other processes are not sharing signals. > > Or is it due to injecting the signal too all of them with the proper > > timing? > > Pressing Ctrl-C between after task_will_free_mem(p) in oom_kill_process() and > before __oom_kill_process() (e.g. dump_header()) made fatal_signal_pending() = T > for all of them. > > > Anyway, could you update your patch and abstract > > if (unlikely(tsk_is_oom_victim(current) || > > fatal_signal_pending(current) || > > current->flags & PF_EXITING)) > > > > in try_charge and reuse it in mem_cgroup_out_of_memory under the > > oom_lock with an explanation please? > > I don't think doing so makes sense, for > > tsk_is_oom_victim(current) = T && fatal_signal_pending(current) == F > > can't happen for mem_cgroup_out_of_memory() under the oom_lock, and > current->flags cannot get PF_EXITING when current is inside > mem_cgroup_out_of_memory(). fatal_signal_pending(current) alone is > appropriate for mem_cgroup_out_of_memory() under the oom_lock because > > tsk_is_oom_victim(current) = F && fatal_signal_pending(current) == T > > can happen there. I meant to use the same check consistently. If we can bypass the charge under a list of conditions in the charge path we should be surely be able to the the same for the oom path. I will not insist but unless there is a strong reason I would prefer that. > Also, doing so might become wrong in future, for mem_cgroup_out_of_memory() > is also called from memory_max_write() which does not bail out upon > PF_EXITING. I don't think we can call memory_max_write() after current > thread got PF_EXITING, but nobody knows what change will happen in future. No, this makes no sense what so ever. -- Michal Hocko SUSE Labs