Messages in this thread | | | Date | Tue, 16 Jun 2009 11:55:40 -0700 | From | Andrew Morton <> | Subject | Re: 2.6.30: hibernation/swsusp lockup due to acpi-cpufreq |
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On Tue, 16 Jun 2009 16:22:17 +0200 Johannes Stezenbach <js@sig21.net> wrote:
> Fix swsusp failure on !SMP > > Commit 01599fca6758d2cd133e78f87426fc851c9ea725 introduced > a regression which caused a backtrace on suspend and > a hang on resume on a Thinkpad T42p (Pentium M CPU). > > Signed-off-by: Johannes Stezenbach <js@sig21.net> > > > --- linux-2.6.30/kernel/up.c.orig 2009-06-16 15:56:28.000000000 +0200 > +++ linux-2.6.30/kernel/up.c 2009-06-16 15:57:27.000000000 +0200 > @@ -10,11 +10,13 @@ > int smp_call_function_single(int cpu, void (*func) (void *info), void *info, > int wait) > { > + unsigned long flags; > + > WARN_ON(cpu != 0); > > - local_irq_disable(); > + local_irq_save(flags); > (func)(info); > - local_irq_enable(); > + local_irq_restore(flags); > > return 0; > }
ok, what's going on here? The patch implies that someone (presumably acpi-cpufreq) is calling smp_call_function_single() with local interrupts disabled. That's a bug on SMP kernels. And it'll generate a trace if it happens:
/* Can deadlock when called with interrupts disabled */ WARN_ON_ONCE(irqs_disabled() && !oops_in_progress);
but nobody has reported such a trace AFAIK?
Also, prior to 01599fca6758d2cd133e78f87426fc851c9ea725, acpi-cpufreq was using work_on_cpu(). If it was calling work_on_cpu() with local interrupts disabled then that would have been a bug too, which could generate might_sleep() or scheduling-while-atomic warnings.
Because it is a bug to call the SMP version of smp_call_function_single() with local interrupts disabled, I don't think we should need to apply the above patch.
But I don't know what we _should_ do because I don't know what the bug is. Are you able to get us a copy of that stack trace?
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