From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail203.messagelabs.com (mail203.messagelabs.com [216.82.254.243]) by kanga.kvack.org (Postfix) with SMTP id C970B6B01EE for ; Thu, 1 Apr 2010 10:01:31 -0400 (EDT) Date: Thu, 1 Apr 2010 15:59:27 +0200 From: Oleg Nesterov Subject: Re: [patch] oom: give current access to memory reserves if it has been killed Message-ID: <20100401135927.GA12460@redhat.com> References: <20100328145528.GA14622@desktop> <20100328162821.GA16765@redhat.com> <20100329112111.GA16971@redhat.com> <20100330154659.GA12416@redhat.com> <20100331175836.GA11635@redhat.com> <20100331204718.GD11635@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org To: David Rientjes Cc: Andrew Morton , anfei , KOSAKI Motohiro , nishimura@mxp.nes.nec.co.jp, KAMEZAWA Hiroyuki , Mel Gorman , linux-mm@kvack.org, linux-kernel@vger.kernel.org List-ID: On 04/01, David Rientjes wrote: > > On Wed, 31 Mar 2010, Oleg Nesterov wrote: > > > Probably something like the patch below makes sense. Note that > > "skip kernel threads" logic is wrong too, we should check PF_KTHREAD. > > Probably it is better to check it in select_bad_process() instead, > > near is_global_init(). > > is_global_init() will be true for p->flags & PF_KTHREAD. No, is_global_init() && PF_KTHREAD have nothing to do with each other. > > @@ -159,13 +172,9 @@ unsigned int oom_badness(struct task_str > > if (p->flags & PF_OOM_ORIGIN) > > return 1000; > > > > - task_lock(p); > > - mm = p->mm; > > - if (!mm) { > > - task_unlock(p); > > + p = find_lock_task_mm(p); > > + if (!p) > > return 0; > > - } > > - > > /* > > * The baseline for the badness score is the proportion of RAM that each > > * task's rss and swap space use. > > @@ -330,12 +339,6 @@ static struct task_struct *select_bad_pr > > *ppoints = 1000; > > } > > > > - /* > > - * skip kernel threads and tasks which have already released > > - * their mm. > > - */ > > - if (!p->mm) > > - continue; > > if (p->signal->oom_score_adj == OOM_SCORE_ADJ_MIN) > > continue; > > You can't do this for the reason I cited in another email, oom_badness() > returning 0 does not exclude a task from being chosen by > selcet_bad_process(), it will use that task if nothing else has been found > yet. We must explicitly filter it from consideration by checking for > !p->mm. Yes, you are right. OK, oom_badness() can never return points < 0, we can make it int and oom_badness() can return -1 if !mm. IOW, - unsigned int points; + int points; ... points = oom_badness(...); if (points >= 0 && (points > *ppoints || !chosen)) chosen = p; Oleg. -- 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