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 79824C433FE for ; Wed, 20 Oct 2021 14:22:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5B05C6023F for ; Wed, 20 Oct 2021 14:22:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230190AbhJTOYR (ORCPT ); Wed, 20 Oct 2021 10:24:17 -0400 Received: from relay.sw.ru ([185.231.240.75]:34038 "EHLO relay.sw.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230123AbhJTOYM (ORCPT ); Wed, 20 Oct 2021 10:24:12 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=virtuozzo.com; s=relay; h=Content-Type:MIME-Version:Date:Message-ID:From: Subject; bh=ggO+FpcKH1wkkXlq2EYHdQ27UcwvObsXNymYB1kX5vo=; b=qICVdC1lEfiKYzFU0 8K47Lgduio85XZ6eCdSooKhVX2NtJObrUJsfhOgPRI1/7qkO7qepJK0z71tuX3axsSQsNHaPSDFiO YQxBeX7rWzBQlrSjhah3Y+4HBc3kWbSLYmtHP5nEt0pcUMUyUUPdH3GRLUO+mhlIXrBHEJUdf0+X8 =; Received: from [172.29.1.17] by relay.sw.ru with esmtp (Exim 4.94.2) (envelope-from ) id 1mdCTb-006bzD-13; Wed, 20 Oct 2021 17:21:55 +0300 Subject: Re: [PATCH memcg 2/3] memcg: remove charge forcinig for dying tasks To: Michal Hocko 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 References: <56180e53-b705-b1be-9b60-75e141c8560c@virtuozzo.com> From: Vasily Averin Message-ID: Date: Wed, 20 Oct 2021 17:21:33 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.13.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. 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. I can't justify why its removal is necessary, but on the other hand, it shouldn't break anything. I can drop it if you think it's necessary. Thank you, Vasily Averin