Messages in this thread | | | Date | Fri, 16 Apr 2010 01:01:50 +0200 (CEST) | From | Thomas Gleixner <> | Subject | Re: [PATCH 3/3] Stop tracing on a schedule bug |
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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 | |