Kernel panic when unpluggin AC adaptor

[Brandon Gooch]

On Tue, May 18, 2010 at 9:04 AM, Giovanni Trematerra
<giovanni.trematerra at gmail.com> wrote:
> On Sat, May 15, 2010 at 9:12 PM, Brandon Gooch
> <jamesbrandongooch at gmail.com> wrote:
>> On Thu, May 13, 2010 at 7:25 PM, Giovanni Trematerra
>> <giovanni.trematerra at gmail.com> wrote:
>>> On Thu, May 13, 2010 at 1:09 AM, Brandon Gooch
>>> <jamesbrandongooch at gmail.com> wrote:
>>>> On Wed, May 12, 2010 at 9:41 AM, Attilio Rao <attilio at freebsd.org> wrote:
>>>>> 2010/5/12 David DEMELIER <demelier.david at gmail.com>:
>>>>>> I remove the patch, and built the kernel (I updated the src this
>>>>>> morning) and it does not panic now. It's really odd. If it reappears
>>>>>> soon I will tell you.
>>>>>
>>>>> I looked at the code with Giovanni and I have the feeling that the
>>>>> race with the idle thread may still be fatal.
>>>>> We need to fix that.
>>>>>
>>>>> Attilio
>>>>>
>>>>
>>>> That seems to be the case, as my laptop shows about an 80-85 % chance
>>>> of experiencing a panic if left idle for long-ish periods of time (2
>>>> to 4 hours). I usually rebuild world or big ports overnight, and more
>>>> often than not I wake up to a panicked machine, same situation every
>>>> time:
>>>>
>>>> ...
>>>> rman_get_bushandle() at rman_get_bushandle+0x1
>>>> sched_idletd() at sched_idletd+0x123
>>>> fork_exit() at fork_exit+0x12a
>>>> fork_trampoline() at fork_trampoline+0xe
>>>> ...
>>>>
>>>> The kernel/userland is rebuilt, the ports are finished compiling --
>>>> it's in the time AFTER the completion of all tasks that the machine
>>>> gets bored and tries to kill itself :)
>>>>
>>>> I have seen the AC adapter plug/unplug "hang" in the past on this
>>>> laptop, but I never made the connection between the events, as
>>>> nowadays my laptop usually stays plugged in :(
>>>>
>>>> Attilio, I hope you can track this one down, let me know if I can do
>>>> anything to help or test...
>>>>
>>>
>>> Attilio and I came up with this patch. It seems ready for stress
>>> testing and review
>>> Please test and report back.
>>>
>>> Thank you
>>>
>>> P.S: all the faults are only mine.
>>
>> I tried the patch, and my kernel panics I panic on boot. I have
>> 8.5MB(!) of JPG images (6 of them) if anyone needs to see them. I'm
>> looking for a place to post them, but if anyone wants, I can send via
>> e-mail...
>
> Hi Brandon,
> Could you please, try this new one? The panic at boot stage should be solved,
> at least I tried on a 8-way machine and all went ok at boot.
> Please, remove WITNESS_SKIPSPIN from your kernel config file.
> This patch might be sub-optimal and contains style(9) error but if it
> works we are
> on the right way.
> Let me know if it works for you.

Applied the patch, built, installed, and booted new kernel: no panic!

I will remove WITNESS_SKIPSPIN and build another kernel. Then I'll
"try" to trigger the panic (by letting my laptop sit idle after a
buildworld session).

Thanks for giving this some attention, I hope you and/or others are
able to get to the bottom of this...

-Brandon