From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932133Ab0DOXCK (ORCPT ); Thu, 15 Apr 2010 19:02:10 -0400 Received: from www.tglx.de ([62.245.132.106]:42913 "EHLO www.tglx.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932096Ab0DOXCH (ORCPT ); Thu, 15 Apr 2010 19:02:07 -0400 Date: Fri, 16 Apr 2010 01:01:50 +0200 (CEST) From: Thomas Gleixner To: Chase Douglas cc: Frederic Weisbecker , linux-kernel@vger.kernel.org, Steven Rostedt , Ingo Molnar , Randy Dunlap Subject: Re: [PATCH 3/3] Stop tracing on a schedule bug In-Reply-To: Message-ID: References: <1271262016-18650-1-git-send-email-chase.douglas@canonical.com> <1271262016-18650-3-git-send-email-chase.douglas@canonical.com> <20100415210357.GG5069@nowhere> User-Agent: Alpine 2.00 (LFD 1167 2008-08-23) MIME-Version: 1.0 Content-Type: MULTIPART/MIXED; BOUNDARY="8323328-1543384268-1271372511=:3625" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. --8323328-1543384268-1271372511=:3625 Content-Type: TEXT/PLAIN; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT On Thu, 15 Apr 2010, Chase Douglas wrote: > On Thu, Apr 15, 2010 at 2:03 PM, Frederic Weisbecker wrote: > > On Wed, Apr 14, 2010 at 12:20:16PM -0400, Chase Douglas wrote: > >> This change adds a tracing_off_event() call to stop tracing on schedule > >> bugs unless tracing_off=none was specified on the commandline. > >> > >> Signed-off-by: Chase Douglas > >> --- > >>  kernel/sched.c |    2 ++ > >>  1 files changed, 2 insertions(+), 0 deletions(-) > >> > >> diff --git a/kernel/sched.c b/kernel/sched.c > >> index 6af210a..439f036 100644 > >> --- a/kernel/sched.c > >> +++ b/kernel/sched.c > >> @@ -3590,6 +3590,8 @@ static noinline void __schedule_bug(struct task_struct *prev) > >>  { > >>       struct pt_regs *regs = get_irq_regs(); > >> > >> +     tracing_off_event(TRACE_EVENT_BUG); > >> + > >>       printk(KERN_ERR "BUG: scheduling while atomic: %s/%d/0x%08x\n", > >>               prev->comm, prev->pid, preempt_count()); > > > > > > > > I would rather call that a TRACE_EVENT_WARN as this is what happens: we > > warn but we continue. > > I tend to think of the TRACE_EVENT_* as an indication of severity and > whether we want to stop the trace by default. From a distro > standpoint, the likelihood that we want to continue tracing after a > __schedule_bug is pretty low. It's easiest if we don't have to tell Well, scheduling while atomic is a BUG, but one of the category which allows the kernel to continue. So in fact it's treated like a WARN_ON. So the tracing_off_event() qualifier should be *_WARN. That's independent of the question whether you want to stop tracing in that very case. Though I agree that the tracer should stop here. > our users to add a kernel command line, especially since grub in > Ubuntu 10.04 LTS is difficult to interact with for end users. That's a serious PITA caused by the "let's mimic the other OS" crowd and no excuse for creating a mess in the kernel. Thanks, tglx --8323328-1543384268-1271372511=:3625--