From: Thomas Gleixner <tglx@linutronix.de>
To: Chase Douglas <chase.douglas@canonical.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>,
linux-kernel@vger.kernel.org,
Steven Rostedt <rostedt@goodmis.org>, Ingo Molnar <mingo@elte.hu>,
Randy Dunlap <randy.dunlap@oracle.com>
Subject: Re: [PATCH 3/3] Stop tracing on a schedule bug
Date: Fri, 16 Apr 2010 01:01:50 +0200 (CEST) [thread overview]
Message-ID: <alpine.LFD.2.00.1004160051390.3625@localhost.localdomain> (raw)
In-Reply-To: <k2u40ec3ea41004151445je53e7ef2u5c0e48e038e4efca@mail.gmail.com>
[-- Attachment #1: Type: TEXT/PLAIN, Size: 1976 bytes --]
On Thu, 15 Apr 2010, Chase Douglas wrote:
> On Thu, Apr 15, 2010 at 2:03 PM, Frederic Weisbecker <fweisbec@gmail.com> 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 <chase.douglas@canonical.com>
> >> ---
> >> 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
next prev parent reply other threads:[~2010-04-15 23:02 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-04-14 16:20 [PATCH 1/3 v4] Add tracing_off_event() to stop tracing when a bug or warning occur Chase Douglas
2010-04-14 16:20 ` [PATCH 2/3] Add tracing_off_event() calls to BUG() and WARN() paths Chase Douglas
2010-04-15 20:57 ` Frederic Weisbecker
2010-04-15 21:49 ` Chase Douglas
2010-04-15 23:15 ` Frederic Weisbecker
2010-04-16 4:13 ` Chase Douglas
2010-04-14 16:20 ` [PATCH 3/3] Stop tracing on a schedule bug Chase Douglas
2010-04-15 21:03 ` Frederic Weisbecker
2010-04-15 21:45 ` Chase Douglas
2010-04-15 23:01 ` Thomas Gleixner [this message]
2010-04-15 23:10 ` Frederic Weisbecker
2010-04-15 23:27 ` Chase Douglas
2010-04-15 23:50 ` Thomas Gleixner
2010-04-16 0:21 ` Thomas Gleixner
2010-04-16 1:49 ` Frederic Weisbecker
2010-04-16 16:41 ` Steven Rostedt
2010-04-16 4:01 ` Chase Douglas
2010-04-16 16:46 ` Steven Rostedt
2010-04-16 17:14 ` Chase Douglas
2010-04-16 18:14 ` Frederic Weisbecker
2010-04-16 19:58 ` Thomas Gleixner
2010-04-19 22:30 ` Chase Douglas
2010-04-16 3:52 ` Chase Douglas
2010-04-15 20:13 ` [PATCH 1/3 v4] Add tracing_off_event() to stop tracing when a bug or warning occur Frederic Weisbecker
-- strict thread matches above, loose matches on Subject: below --
2010-03-18 13:48 [PATCH 1/3] " Chase Douglas
2010-03-18 13:48 ` [PATCH 3/3] Stop tracing on a schedule bug Chase Douglas
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