Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759242AbYFOQ0H (ORCPT ); Sun, 15 Jun 2008 12:26:07 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758341AbYFOQZz (ORCPT ); Sun, 15 Jun 2008 12:25:55 -0400 Received: from ug-out-1314.google.com ([66.249.92.171]:57632 "EHLO ug-out-1314.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758321AbYFOQZy (ORCPT ); Sun, 15 Jun 2008 12:25:54 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; b=chAy0aaXQWqcllg2zEgeIO3aHQH5pVQKNKmU4xC9DlNjaGZwBYF+52Yu6eTswTCeSy LS8cOu5vzzEzGkP1Y6Lxw43iHntmr9Aokf4EK1Dahsum/I3iSUF7YLjLg6POTQLxBJ9u 9f/A2yafA/IZXu4ISABPdgMueDxQwLP2oRnjI= Date: Sun, 15 Jun 2008 20:21:50 +0400 From: Alexey Dobriyan To: "Paul E. McKenney" Cc: Oleg Nesterov , Adrian Bunk , "Rafael J. Wysocki" , Linux Kernel Mailing List , Linus Torvalds Subject: Re: [Bug #10815] 2.6.26-rc4: RIP find_pid_ns+0x6b/0xa0 Message-ID: <20080615162150.GA8289@martell.zuzino.mipt.ru> References: <20080613135255.GB21341@cs181133002.pp.htv.fi> <20080614144200.GA26421@linux.vnet.ibm.com> <20080614145839.GA10523@tv-sign.ru> <20080614181212.GB26421@linux.vnet.ibm.com> <20080614194338.GA4820@martell.zuzino.mipt.ru> <20080615033001.GE26421@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080615033001.GE26421@linux.vnet.ibm.com> User-Agent: Mutt/1.5.16 (2007-06-09) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3861 Lines: 84 On Sat, Jun 14, 2008 at 08:30:01PM -0700, Paul E. McKenney wrote: > On Sat, Jun 14, 2008 at 11:43:38PM +0400, Alexey Dobriyan wrote: > > On Sat, Jun 14, 2008 at 11:12:12AM -0700, Paul E. McKenney wrote: > > > On Sat, Jun 14, 2008 at 06:58:39PM +0400, Oleg Nesterov wrote: > > > > On 06/14, Paul E. McKenney wrote: > > > > > > > > > > On Fri, Jun 13, 2008 at 04:52:55PM +0300, Adrian Bunk wrote: > > > > > > On Sat, Jun 07, 2008 at 10:42:57PM +0200, Rafael J. Wysocki wrote: > > > > > > > This message has been generated automatically as a part of a report > > > > > > > of recent regressions. > > > > > > > > > > > > > > The following bug entry is on the current list of known regressions > > > > > > > from 2.6.25. Please verify if it still should be listed. > > > > > > > > > > > > > > > > > > > > > Bug-Entry : http://bugzilla.kernel.org/show_bug.cgi?id=10815 > > > > > > > Subject : 2.6.26-rc4: RIP find_pid_ns+0x6b/0xa0 > > > > > > > Submitter : Alexey Dobriyan > > > > > > > Date : 2008-05-27 09:23 (12 days old) > > > > > > > References : http://lkml.org/lkml/2008/5/27/9 > > > > > > > Handled-By : Oleg Nesterov > > > > > > > Linus Torvalds > > > > > > > Paul E. McKenney > > > > > > > Patch : http://lkml.org/lkml/2008/5/28/16 > > > > > > > > > > > > What happened with this issue? > > > > > > > > > > The patch listed above works for me, passes rcutorture, &c. However, > > > > > I never have been able to reproduce the original problem, so cannot say > > > > > whether it qualifies as a fix. > > > > > > > > I doubt very much RCU was the reason of this problem. > > > > > > Although I very much appreciate your confidence in my code, it is new > > > code, so therefore under suspicion. > > > > > > > Alexey, how did you trigger this problem? > > > > > > One of them involved running LTP while doing 170 kernel builds in > > > parallel. > > > > My gut feeling is that find_pid_ns oops, __d_lookup oops and > > __call_for_each_cic oops are the same bug. > > > > And rcutorture failures I've mentioned to Paul privately. > > Yep, running rcutorture in parallel with LTP, which didn't reproduce > for me either. > > Did the patch at http://lkml.org/lkml/2008/5/28/16 help? > > > Oleg, debugging you've posted never triggered. > > > > kerneloops suggests that I'm alone. :-( > > Assuming that the above patch didn't help... As a desperation measure, > I could suggest the following patch. > --- linux-2.6.26-rc4/kernel/rcupreempt.c > +++ linux-2.6.26-rc4-alexey/kernel/rcupreempt.c > @@ -77,7 +77,7 @@ > * > * GP in GP_STAGES stands for Grace Period ;) > */ > -#define GP_STAGES 2 > +#define GP_STAGES 3 > struct rcu_data { > spinlock_t lock; /* Protect rcu_data fields. */ > long completed; /* Number of last completed batch. */ Both patches (independently) do not help with rcutortures failures: [ 58.968404] rcu-torture:--- Start of test: nreaders=4 nfakewriters=4 stat_interval=0 verbose=0 test_no_idle_hz=0 shuffle_interval = 5 [ 159.044524] rcu-torture: rtc: 0000000000000000 ver: 53859 tfle: 0 rta: 53859 rtaf: 18 rtf: 53797 rtmbe: 0 [ 159.044527] rcu-torture: !!! Reader Pipe: 65565142 4275 1 0 0 0 0 0 0 0 0 [ 159.044529] rcu-torture: Reader Batch: 65564196 5207 7 3 1 1 0 1 1 0 1 [ 159.044530] rcu-torture: Free-Block Circulation: 53858 53853 53846 53843 53834 53825 53816 53808 53803 53797 0 [ 159.044976] rcu-torture:--- End of test: FAILURE: nreaders=4 nfakewriters=4 stat_interval=0 verbose=0 test_no_idle_hz=0 shuffle_interval = 5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/