From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1422919Ab2LFUol (ORCPT ); Thu, 6 Dec 2012 15:44:41 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:40435 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753499Ab2LFUoj (ORCPT ); Thu, 6 Dec 2012 15:44:39 -0500 Message-ID: <50C10391.4040903@canonical.com> Date: Thu, 06 Dec 2012 15:44:01 -0500 From: Joseph Salisbury User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:16.0) Gecko/20121017 Thunderbird/16.0.1 MIME-Version: 1.0 To: Oleg Nesterov CC: Ben Hutchings , "Rafael J. Wysocki" , Herton Krzesinski , linux-kernel@vger.kernel.org Subject: Re: freezer: exec should clear PF_NOFREEZE along with PF_KTHREAD References: <50BF9CC2.7070705@canonical.com> <1354762294.17107.157.camel@deadeye.wl.decadent.org.uk> <20121206124201.GA30705@redhat.com> In-Reply-To: <20121206124201.GA30705@redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/06/2012 07:42 AM, Oleg Nesterov wrote: > Hi, > > (add lkml) > > On 12/06, Ben Hutchings wrote: >> On Wed, 2012-12-05 at 14:13 -0500, Joseph Salisbury wrote: >> >>> Hi Oleg, >>> >>> A bug was opened against the Ubuntu kernel[0]. It was found that >>> reverting commit b40a79591ca918e7b91b0d9b6abd5d00f2e88c19 resolved this >>> bug, and allowed suspend/resume to work properly. >>> >>> I see that you are the author of this patch, so I wanted to run it by >>> you. I was thinking of requesting a revert for 3.2 stable, but I wanted >>> to get your feedback first. >>> >>> Thanks, >>> >>> Joe >>> >>> >>> [0] https://bugs.launchpad.net/ubuntu/+source/v86d/+bug/1080530 >> If I understand this rightly: >> 1. Suspend is aborted because the v86d usermodehelper cannot be frozen. >> 2. Before this fix, usermodehelpers could inherit PF_NOFREEZE (what >> could possibly go wrong with that?!), which is why this didn't >> previously happen. > Yes, try_to_freeze_tasks() ignores PF_NOFREEZE tasks > >> 3. However, usermodehelpers are supposed to be disabled while the >> freezer is running. Why is this one still running? > __usermodehelper_disable() doesn't try to kill/stop/whatever the already > spawned tasks... > > The question is, why v86d refuses to freeze? It sleeps in TASK_INTERRUPTIBLE. > > > Oh... I seem to understand. This is 3.2 kernel, it also has PF_FREEZER_NOSIG. > which should be cleared along with PF_NOFREEZE. > > This flag was removed upstream, but the older kernel need the fix. Could > you test the patch below? > > Oleg. > > --- a/fs/exec.c > +++ b/fs/exec.c > @@ -1084,7 +1084,7 @@ int flush_old_exec(struct linux_binprm * > > set_fs(USER_DS); > current->flags &= > - ~(PF_RANDOMIZE | PF_FORKNOEXEC | PF_KTHREAD | PF_NOFREEZE); > + ~(PF_RANDOMIZE | PF_FORKNOEXEC | PF_KTHREAD | PF_NOFREEZE | PF_FREEZER_NOSIG); > flush_thread(); > current->personality &= ~bprm->per_clear; > > Hi Oleg, A couple of people have tested your patch and report if fixes the suspend/resume bug[0]. Thanks for the quick fix! Will you be requesting this patch in the stable kernels? Thanks again, Joe [0] https://bugs.launchpad.net/bugs/1080530