Kernel panic when unpluggin AC adaptor

David DEMELIER demelier.david at
Wed May 26 09:14:28 UTC 2010

2010/5/25 Giovanni Trematerra <giovanni.trematerra at>:
> On Tue, May 25, 2010 at 5:52 PM, David DEMELIER
> <demelier.david at> wrote:
>> 2010/5/25 Giovanni Trematerra <giovanni.trematerra at>:
>>> On Mon, May 24, 2010 at 9:43 PM, David DEMELIER
>>> <demelier.david at> wrote:
>>>> 2010/5/12 Giovanni Trematerra <giovanni.trematerra at>:
>>>>> On Fri, May 7, 2010 at 8:33 PM, Demelier David <demelier.david at> wrote:
>>>>>> Le Vendredi 07 mai 2010 à 18:22 +0200, Giovanni Trematerra a écrit :
>>>>>>> On Fri, May 7, 2010 at 2:08 PM, Demelier David <demelier.david at> wrote:
>>>>>>> > Hi,
>>>>>>> >        I noticed that pluggin the AC adaptor when I boot without it does not
>>>>>>> >        panic. It only panic when removing it.
>>>>>>> >
>>>>>>> >        Maybe that could help ?
>>>>>>> >
>>>>>>> Good to know. The problem lies somewhere when performance state change.
>>>>>>> In your case it happens when you remove AC adaptor. Let's hope someone on
>>>>>>> acpi@ ml comes up with a good idea.
>>>>>> Okay so for the moment no change, I'll wait for someone with an idea
>>>>>> that could solve my problem. For me because the panic only happens when
>>>>>> changing profile from ac plugged -> ac unplugged (and not the reverse) I
>>>>>> would think it's a cpu related acpi issue.
>>>>> I looked deeper and it seems to me that when you unplug the AC
>>>>> adapter, acpi_cpu_notify calls acpi_cpu_cx_cst that try to allocate a
>>>>> new cx_ptr->p_lvlx  via acpi_PkgGas.
>>>>> If acpi_PkgGas set cx_ptr->p_lvlx to NULL for any reasons you'll have
>>>>> the panic that you reported.
>>>>> A solution would be to set acpi_cpu_hook to NULL so acpi_cpu_idle won't call it.
>>>>> I need some time to have a patch because of the possible race between
>>>>> acpi_cpu_notify and
>>>>> acpi_cpu_idle during set acpi_cpu_hook to NULL.
>>>>> if you have time and want panic your system you could try the attached
>>>>> patch, just to be
>>>>> sure that we catch it.
>>>> Hi, it paniced today ! I don't know why it randomly panic but it did,
>>>> the backtrace didn't change. There is a picture about the panic :
>>> What was you trying? acpi_idle5.diff.txt patch?
>>> How did it panic? Unplugging AC adapter?
>> Hi, I tried this one : lvlx.diff.txt. Yes by unplugging the AC adapter.
> This is an old one. Could you try acpi_idle5.diff.txt? I kept you in
> Cc when I sent to
> the list. If you have problems, let me know, I'll resend to you  the patch.
> Thank you.

Hi, it panic'ed with the same backtrace.


Demelier David

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