From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail190.messagelabs.com (mail190.messagelabs.com [216.82.249.51]) by kanga.kvack.org (Postfix) with SMTP id 58A8A6B01F5 for ; Tue, 6 Apr 2010 09:40:55 -0400 (EDT) Date: Tue, 6 Apr 2010 15:38:47 +0200 From: Oleg Nesterov Subject: Re: [PATCH -mm 2/4] oom: select_bad_process: PF_EXITING check should take ->mm into account Message-ID: <20100406133847.GA10039@redhat.com> References: <20100331204718.GD11635@redhat.com> <20100401135927.GA12460@redhat.com> <20100402111406.GA4432@redhat.com> <20100402183057.GA31723@redhat.com> <20100402183216.GC31723@redhat.com> <20100406114235.GA3965@desktop> <20100406121811.GA6802@redhat.com> <20100406130518.GB3965@desktop> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100406130518.GB3965@desktop> Sender: owner-linux-mm@kvack.org To: anfei Cc: David Rientjes , Andrew Morton , KOSAKI Motohiro , nishimura@mxp.nes.nec.co.jp, KAMEZAWA Hiroyuki , Mel Gorman , linux-mm@kvack.org, linux-kernel@vger.kernel.org List-ID: On 04/06, anfei wrote: > > On Tue, Apr 06, 2010 at 02:18:11PM +0200, Oleg Nesterov wrote: > > > > I do not really know what is the "right" solution. Even if we fix this > > check for mt case, we also have CLONE_VM tasks. > > > What about checking mm->mm_users too? If there are any other users, > just let badness judge. CLONE_VM tasks but not mt seem rare, and > badness doesn't consider it too. Even if we forget about get_task_mm() which increments mm_users, it is not clear to me how to do this check correctly. Say, mm_users > 1 but SIGNAL_GROUP_EXIT is set. This means this process is exiting and (ignoring CLONE_VM task) it is going to release its ->mm. But otoh mm can be NULL. Perhaps we can do if ((PF_EXITING && thread_group_empty(p) || (p->signal->flags & SIGNAL_GROUP_EXIT) { // OK, it is exiting bool has_mm = false; do { if (t->mm) { has_mm = true; break; } } while_each_thread(p, t); if (!has_mm) continue; if (p != current) return ERR_PTR(-1); ... } I dunno. 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