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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 439EDC433EF for ; Wed, 20 Oct 2021 14:57:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 29B38611EF for ; Wed, 20 Oct 2021 14:57:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230242AbhJTPAI (ORCPT ); Wed, 20 Oct 2021 11:00:08 -0400 Received: from smtp-out2.suse.de ([195.135.220.29]:57952 "EHLO smtp-out2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229695AbhJTPAH (ORCPT ); Wed, 20 Oct 2021 11:00:07 -0400 Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out2.suse.de (Postfix) with ESMTP id E2DC31F770; Wed, 20 Oct 2021 14:57:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1634741871; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=INWX6iRMgRgAeyFdp/SkdRvXgxqnNTdg9wvYzeiWaBA=; b=iTmcOtZYuIOlWrscgR3H2hvlT6MI5R92DnWgHIy7wONcN+PKYWUyK570QvFDSk1qih5g3d lBlmdgglQ/UhLnEdjefJXfInoHJwAijYNaUwZHjo5JQwFqSQfIlciUH0AC2Nx52pKVqGt2 m56/Jk90dWeSYs1B62hBbsy3Xqw+q3A= Received: from suse.cz (unknown [10.100.201.86]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by relay2.suse.de (Postfix) with ESMTPS id 4BDC7A3B85; Wed, 20 Oct 2021 14:57:51 +0000 (UTC) Date: Wed, 20 Oct 2021 16:57:50 +0200 From: Michal Hocko To: Vasily Averin Cc: Johannes Weiner , Vladimir Davydov , Andrew Morton , Roman Gushchin , Uladzislau Rezki , Vlastimil Babka , Shakeel Butt , Mel Gorman , Tetsuo Handa , cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel@openvz.org Subject: Re: [PATCH memcg 2/3] memcg: remove charge forcinig for dying tasks Message-ID: References: <56180e53-b705-b1be-9b60-75e141c8560c@virtuozzo.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed 20-10-21 17:21:33, Vasily Averin wrote: > On 20.10.2021 15:41, Michal Hocko wrote: > > On Wed 20-10-21 15:13:46, Vasily Averin wrote: > >> ToDo: should we keep task_is_dying() in mem_cgroup_out_of_memory() ? > >> > >> Signed-off-by: Vasily Averin > >> --- > >> mm/memcontrol.c | 20 +++++++------------- > >> 1 file changed, 7 insertions(+), 13 deletions(-) > >> > >> diff --git a/mm/memcontrol.c b/mm/memcontrol.c > >> index 6da5020a8656..74a7379dbac1 100644 > >> --- a/mm/memcontrol.c > >> +++ b/mm/memcontrol.c > >> @@ -239,7 +239,7 @@ enum res_type { > >> iter != NULL; \ > >> iter = mem_cgroup_iter(NULL, iter, NULL)) > >> > >> -static inline bool should_force_charge(void) > >> +static inline bool task_is_dying(void) > >> { > >> return tsk_is_oom_victim(current) || fatal_signal_pending(current) || > >> (current->flags & PF_EXITING); > >> @@ -1575,7 +1575,7 @@ static bool mem_cgroup_out_of_memory(struct mem_cgroup *memcg, gfp_t gfp_mask, > >> * A few threads which were not waiting at mutex_lock_killable() can > >> * fail to bail out. Therefore, check again after holding oom_lock. > >> */ > >> - ret = should_force_charge() || out_of_memory(&oc); > >> + ret = task_is_dying() || out_of_memory(&oc); > > > > Why are you keeping the task_is_dying check here? IIRC I have already > > pointed out that out_of_memory already has some means to do a bypass > > when needed. > > It was a misunderstanding. Sorry if I made you confused. > I've been waiting for your final decision. > > I have no good arguments "pro" or strong objection "contra". > However, I prefer to keep task_is_dying() so as not to touch other tasks unnecessarily. One argument for removing it from here is the maintainability. Now you have a memcg specific check which is not in sync with the oom. E.g. out_of_memory does task_will_free_mem as the very first thing. You are also automatically excluding oom killer for cases where that might make a sense. -- Michal Hocko SUSE Labs