From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756947AbZBFOBx (ORCPT ); Fri, 6 Feb 2009 09:01:53 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752301AbZBFOBn (ORCPT ); Fri, 6 Feb 2009 09:01:43 -0500 Received: from mx3.mail.elte.hu ([157.181.1.138]:49765 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751986AbZBFOBm (ORCPT ); Fri, 6 Feb 2009 09:01:42 -0500 Date: Fri, 6 Feb 2009 15:01:34 +0100 From: Ingo Molnar To: Mike Galbraith , Peter Zijlstra , Oleg Nesterov Cc: LKML , Thomas Gleixner Subject: Re: x86-tip.today: flood of WARNING: at include/linux/sched.h:2238 run_posix_cpu_timers+0xea/0x79f() Message-ID: <20090206140134.GC3415@elte.hu> References: <1233910614.23431.18.camel@marge.simson.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1233910614.23431.18.camel@marge.simson.net> User-Agent: Mutt/1.5.18 (2008-05-17) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.3 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Mike Galbraith wrote: > Greetings, > > Futzing with kerneltop this morning, I fired up amarok to give it > something light to monitor while I hunt missing events. Something bad > happened, and when I finally (SysRq-E took minutes) got control of box > back, dmesg was full of a steady stream of the below. > > That warning can be kinda unfriendly. > > > [ 9964.600004] ------------[ cut here ]------------ > [ 9964.600006] WARNING: at include/linux/sched.h:2238 run_posix_cpu_timers+0xea/0x79f() ah, that's Peter's stuff: 4cd4c1b: timers: split process wide cpu clocks/timers 32bd671: signal: re-add dead task accumulation stats. The discussion with Oleg resulted in the conclusion i think that the warning is spurious and should be removed. I've commited the minimal fix below to tip:master. There's more fixes needed too but this should solve the warning flood at least. Ingo ------------------------> >>From 7d8e23df69820e6be42bcc41d441f4860e8c76f7 Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Fri, 6 Feb 2009 14:57:51 +0100 Subject: [PATCH] timers: split process wide cpu clocks/timers, remove spurious warning Mike Galbraith reported that the new warning in thread_group_cputimer() triggers en masse with Amarok running. Oleg Nesterov observed: Can't fastpath_timer_check()->thread_group_cputimer() have the false warning too? Suppose we had the timer, then posix_cpu_timer_del() removes this timer, but task_cputime_zero(&sig->cputime_expires) still not true. Remove the spurious debug warning. Reported-by: Mike Galbraith Explained-by: Oleg Nesterov Signed-off-by: Ingo Molnar --- include/linux/sched.h | 2 -- 1 files changed, 0 insertions(+), 2 deletions(-) diff --git a/include/linux/sched.h b/include/linux/sched.h index 082d761..7939291 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -2208,8 +2208,6 @@ void thread_group_cputimer(struct task_struct *tsk, struct task_cputime *times) struct thread_group_cputimer *cputimer = &tsk->signal->cputimer; unsigned long flags; - WARN_ON(!cputimer->running); - spin_lock_irqsave(&cputimer->lock, flags); *times = cputimer->cputime; spin_unlock_irqrestore(&cputimer->lock, flags);