From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f43.google.com (mail-wm0-f43.google.com [74.125.82.43]) by kanga.kvack.org (Postfix) with ESMTP id 63BA46B0253 for ; Mon, 22 Feb 2016 06:39:36 -0500 (EST) Received: by mail-wm0-f43.google.com with SMTP id a4so158353265wme.1 for ; Mon, 22 Feb 2016 03:39:36 -0800 (PST) Received: from mx2.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id u184si32139753wmd.92.2016.02.22.03.39.34 for (version=TLS1 cipher=AES128-SHA bits=128/128); Mon, 22 Feb 2016 03:39:35 -0800 (PST) Date: Mon, 22 Feb 2016 12:39:33 +0100 From: Michal Hocko Subject: Re: [PATCH] mm,oom: don't kill children of oom_task_origin() process. Message-ID: <20160222113933.GE17938@dhcp22.suse.cz> References: <1455944042-7614-1-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: <1455944042-7614-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp> Sender: owner-linux-mm@kvack.org List-ID: To: Tetsuo Handa Cc: rientjes@google.com, linux-mm@kvack.org On Sat 20-02-16 13:54:02, Tetsuo Handa wrote: > Selecting a child of the candidate which was chosen by oom_task_origin() > is pointless. We want to kill the candidate first. NACK, until we see a clear evidence that there is a real application which triggers ksm/swapoff from a context where this would make a difference. There is no good reason to add new checks to an already subtle code just for something that even doesn't matter in the real life. > Signed-off-by: Tetsuo Handa > --- > mm/oom_kill.c | 9 +++++++++ > 1 file changed, 9 insertions(+) > > diff --git a/mm/oom_kill.c b/mm/oom_kill.c > index 28d6a32..703537a2 100644 > --- a/mm/oom_kill.c > +++ b/mm/oom_kill.c > @@ -697,6 +697,14 @@ void oom_kill_process(struct oom_control *oc, struct task_struct *p, > if (__ratelimit(&oom_rs)) > dump_header(oc, p, memcg); > > + /* > + * We must send SEGKILL on p rather than p's children in order to make > + * sure that oom_task_origin(p) becomes false. Printing the score value > + * which is (ULONG_MAX * 1000 / totalpages) is useless for this case. > + */ > + if (oom_task_origin(p)) > + goto kill; > + > pr_err("%s: Kill process %d (%s) score %u or sacrifice child\n", > message, task_pid_nr(p), p->comm, points); > > @@ -728,6 +736,7 @@ void oom_kill_process(struct oom_control *oc, struct task_struct *p, > } > read_unlock(&tasklist_lock); > > + kill: > p = find_lock_task_mm(victim); > if (!p) { > put_task_struct(victim); > -- > 1.8.3.1 > > -- > 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 -- 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