From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758774Ab0FBVfL (ORCPT ); Wed, 2 Jun 2010 17:35:11 -0400 Received: from mx1.redhat.com ([209.132.183.28]:16806 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753654Ab0FBVfI (ORCPT ); Wed, 2 Jun 2010 17:35:08 -0400 Date: Wed, 2 Jun 2010 23:33:32 +0200 From: Oleg Nesterov To: David Rientjes Cc: KOSAKI Motohiro , LKML , linux-mm , Andrew Morton , KAMEZAWA Hiroyuki , Nick Piggin Subject: Re: [PATCH 1/5] oom: select_bad_process: check PF_KTHREAD instead of !mm to skip kthreads Message-ID: <20100602213331.GA31949@redhat.com> References: <20100601212023.GA24917@redhat.com> <20100602223612.F52D.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/02, David Rientjes wrote: > > On Wed, 2 Jun 2010, KOSAKI Motohiro wrote: > > > > Again, the question is whether or not the fix is rc material or not, > > > otherwise there's no difference in the route that it gets upstream: the > > > patch is duplicated in both series. If you feel that this minor issue > > > (which has never been reported in at least the last three years and > > > doesn't have any side effects other than a couple of millisecond delay > > > until unuse_mm() when the oom killer will kill something else) should be > > > addressed in 2.6.35-rc2, then that's a conversation to be had with Andrew. > > > > Well, we have bugfix-at-first development rule. Why do you refuse our > > development process? > > This isn't a bugfix, it simply prevents a recall to the oom killer after > the kthread has called unuse_mm(). Please show where any side effects of > oom killing a kthread, which cannot exit, as a result of use_mm() causes a > problem _anywhere_. I already showed you the side effects, but you removed this part in your reply. >>From http://marc.info/?l=linux-kernel&m=127542732121077 It can't die but force_sig() does bad things which shouldn't be done with workqueue thread. Note that it removes SIG_IGN, sets SIGNAL_GROUP_EXIT, makes signal_pending/fatal_signal_pedning true, etc. A workqueue thread must not run with SIGNAL_GROUP_EXIT set, SIGKILL must be ignored, signal_pending() must not be true. This is bug. It is minor, agreed, currently use_mm() is only used by aio. Oleg. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail143.messagelabs.com (mail143.messagelabs.com [216.82.254.35]) by kanga.kvack.org (Postfix) with SMTP id A04CB6B01AC for ; Wed, 2 Jun 2010 17:34:59 -0400 (EDT) Date: Wed, 2 Jun 2010 23:33:32 +0200 From: Oleg Nesterov Subject: Re: [PATCH 1/5] oom: select_bad_process: check PF_KTHREAD instead of !mm to skip kthreads Message-ID: <20100602213331.GA31949@redhat.com> References: <20100601212023.GA24917@redhat.com> <20100602223612.F52D.A69D9226@jp.fujitsu.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: KOSAKI Motohiro , LKML , linux-mm , Andrew Morton , KAMEZAWA Hiroyuki , Nick Piggin List-ID: On 06/02, David Rientjes wrote: > > On Wed, 2 Jun 2010, KOSAKI Motohiro wrote: > > > > Again, the question is whether or not the fix is rc material or not, > > > otherwise there's no difference in the route that it gets upstream: the > > > patch is duplicated in both series. If you feel that this minor issue > > > (which has never been reported in at least the last three years and > > > doesn't have any side effects other than a couple of millisecond delay > > > until unuse_mm() when the oom killer will kill something else) should be > > > addressed in 2.6.35-rc2, then that's a conversation to be had with Andrew. > > > > Well, we have bugfix-at-first development rule. Why do you refuse our > > development process? > > This isn't a bugfix, it simply prevents a recall to the oom killer after > the kthread has called unuse_mm(). Please show where any side effects of > oom killing a kthread, which cannot exit, as a result of use_mm() causes a > problem _anywhere_. I already showed you the side effects, but you removed this part in your reply. >>From http://marc.info/?l=linux-kernel&m=127542732121077 It can't die but force_sig() does bad things which shouldn't be done with workqueue thread. Note that it removes SIG_IGN, sets SIGNAL_GROUP_EXIT, makes signal_pending/fatal_signal_pedning true, etc. A workqueue thread must not run with SIGNAL_GROUP_EXIT set, SIGKILL must be ignored, signal_pending() must not be true. This is bug. It is minor, agreed, currently use_mm() is only used by aio. 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