From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wg0-f52.google.com (mail-wg0-f52.google.com [74.125.82.52]) by kanga.kvack.org (Postfix) with ESMTP id 59D6D6B0035 for ; Tue, 23 Sep 2014 14:30:24 -0400 (EDT) Received: by mail-wg0-f52.google.com with SMTP id n12so3256277wgh.35 for ; Tue, 23 Sep 2014 11:30:23 -0700 (PDT) Received: from mail-wg0-x22e.google.com (mail-wg0-x22e.google.com [2a00:1450:400c:c00::22e]) by mx.google.com with ESMTPS id mc4si16198416wjb.75.2014.09.23.11.30.22 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Tue, 23 Sep 2014 11:30:22 -0700 (PDT) Received: by mail-wg0-f46.google.com with SMTP id a1so4806335wgh.29 for ; Tue, 23 Sep 2014 11:30:22 -0700 (PDT) Date: Tue, 23 Sep 2014 20:30:20 +0200 From: Michal Hocko Subject: Re: [PATCH] oom: break after selecting process to kill Message-ID: <20140923183020.GD29528@dhcp22.suse.cz> References: <20140911213338.GA4098@localhost.localdomain> <20140912080853.GA12156@dhcp22.suse.cz> <20140912082329.GA12330@localhost.localdomain> <20140912121817.GE12156@dhcp22.suse.cz> <20140912122143.GA20622@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: David Rientjes Cc: Niv Yehezkel , linux-mm@kvack.org, akpm@linux-foundation.org, hannes@cmpxchg.org, oleg@redhat.com On Sun 14-09-14 13:46:15, David Rientjes wrote: > On Fri, 12 Sep 2014, Niv Yehezkel wrote: > > > > > diff --git a/mm/oom_kill.c b/mm/oom_kill.c > > > > index 1e11df8..3203578 100644 > > > > --- a/mm/oom_kill.c > > > > +++ b/mm/oom_kill.c > > > > @@ -315,7 +315,7 @@ static struct task_struct *select_bad_process(unsigned int *ppoints, > > > > case OOM_SCAN_SELECT: > > > > chosen = p; > > > > chosen_points = ULONG_MAX; > > > > - /* fall through */ > > > > + break; > > > > case OOM_SCAN_CONTINUE: > > > > continue; > > > > case OOM_SCAN_ABORT: > > > > @@ -324,6 +324,8 @@ static struct task_struct *select_bad_process(unsigned int *ppoints, > > > > case OOM_SCAN_OK: > > > > break; > > > > }; > > > > + if (chosen_points == ULONG_MAX) > > > > + break; > > > > points = oom_badness(p, NULL, nodemask, totalpages); > > > > if (!points || points < chosen_points) > > > > continue; > > > > -- > > > > 1.7.10.4 > > > > > > > > > > > > > -- > > > Michal Hocko > > > SUSE Labs > > > > As mentioned earlier, there's no need to keep iterating over all > > running processes once the process with the highest score has been found. > > > > This would lead to unnecessary oom killing since we may miss a process > that returns OOM_SCAN_ABORT simply because it is later in the tasklist (we > want to defer oom killing if there is an exiting process or an oom kill > victim hasn't exited yet). NACK. Good point David. I have completely missed this part! -- 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