Re: 3.1rc10 null pointer dereference ideapad_backlight_notify_power

Ike Panhc
2011-10-20T01:32:30Z

On 10/20/2011 04:20 AM, David Rientjes wrote:
> On Wed, 19 Oct 2011, Sam Tygier wrote:
>
>> In kernels 3.1rc9 and 3.1rc10 (from the ubuntu mainline repo) I get a crash
>> when disabling and then enabling the screen backlight with the alt+f2 key on a
>> lenovo ideapad S12 (intel version). The crash does not occur with 3.0 kernels
>> in ubuntu. I have not tested earlier 3.1 rcs.
>>
>> The crash message scrolls to fast to see, it is not writen to a log, and i
>> dont see it on a USB serial console (I may be doing something wrong, but I do
>> see other messages during boot). I managed to get some photos of the message.
>> interesting parts are:
>>
>> BUG: unable to handle kernel NULL pointer dereference at 00000008
>> IP: [<f807b29e>] ideapad_backlight_notify_power+0x2e/0x40 [ideapad_laptop]
>> *pde = 00000000
>> Oops: 0002 [#1] SMP
>>
>> call trace functions:
>> ideapad_acpi_notify
>> acpi_device_notify
>> acpi_ev_notify_dispach
>> acpi_os_execute_deferred
>> process_one_work
>> ? acpi_os_wait_events_complete
>> ????????? can't read this one
>> kthread
>> kthread_bind
>> kernel_thread_helper
>>
>> i put the photos at http://www.hep.manchester.ac.uk/u/sam/pub/ideapad/
>>
>> if it would be helpfull, i could try a few more times for sharper photos.
>> please let me know if there is any other useful information you need.
>>
>
> Looks light it may be changed via the acpi video driver where ->blight is
> NULL. Adding Ike and Matthew to the cc.
>

This issue has been reported[1] and patch[2] is ready.

[1] http://www.mail-archive.com/platform-driver-x86@vger.kernel.org/msg02340.html

[2] http://www.mail-archive.com/platform-driver-x86@vger.kernel.org/msg02343.html
http://www.mail-archive.com/platform-driver-x86@vger.kernel.org/msg02346.html

Thanks for reporting this issue.