panic on shutdown

Maxim Maximov mcsi at
Fri Sep 3 10:21:29 PDT 2004

Nate Lawson wrote:
> John Baldwin wrote:
>> On Thursday 02 September 2004 11:51 pm, Maxim Maximov wrote:
>>> Hello.
>>>     I just got this panic on shutdown using Power button, hand 
>>> transcribed:
>>> Syncing disks: <numbers>
>>> No buffers busy after final sync
>>> Uptime: 21m53s
>>> Powering system off using ACPI
>>> panic: lock (sleep mutex) Giant not locked @
>>> /usr/src/sys/kern/kern_timeout.c:279
>>> cpuid = 0
>>> KDB: enter: panic
>>> ACPI power-off failed - timeout
>>> Rebooting...
>>> cpu_reset: called on cpu#1
>>> cpu_reset: Stopping other CPUs
>>> Here it hung until I pressed Power button again. Then it shut down.
>> Looks like the timeout/callout routine dropped Giant more than it 
>> acquired it.
> I don't see how this could be triggered by ACPI.  If you reboot the 
> system with ACPI disabled (or enabled), do you also get this message? 

My system can't boot with ACPI disabled.

Also I want to mention that this panic is rare. I've seen it about 10 
times in 2-3 months of everyday rebooting.

And by the way, the command issued to shut the system down was 'halt -p'

> We 
> don't acquire or release Giant explicitly and the device and interrupt 
> are both marked MPSAFE.  Well, we use Giant for busdma to set up the 1 
> MB trampoline in low memory for resume but that shouldn't affect this 
> unless there's a bug in busdma.
> BTW, why doesn't "panic" from the debugger prompt actually reset the 
> system any more?
> -Nate

Maxim Maximov

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