Random ocassional graphics freeze on Intel chipset

[Alex Villací­s Lasso]

El 02/10/13 05:19, Chris Wilson escribió:
> On Tue, Oct 01, 2013 at 06:15:00PM -0500, Alex Villací­s Lasso wrote:
>> I have seen this graphics freeze under stock 3.10.x from the Fedora
>> 18 x86_64 distro, and also with vanilla compiled 3.11 and 3.12-rc3.
>> After a few hours of working, the screen stops updating. The mouse
>> pointer moves around and changes if moved over different parts of
>> the screen, but the display itself does not change anymore. If I
>> check /sys/kernel/debug/dri/0/i915_error_state right then (via a
>> remote ssh), there is no error captured. However, if I do "echo 1 >
>> /sys/kernel/debug/dri/0/i915_wedged", after a few moments an error
>> is captured, as well as messages in the kernel log, both of which
>> are attached. If I try to restart the gnome-shell session, I get the
>> KMS console, and then the start of the graphic login, but then the
>> graphic login itself freezes again.
>>
>> Is the attached information enough to diagnose the issue?
> Afaict it was a userspace hang, the GPU was rightfully idle. Only on the
> reset did it actually die.
If I do "echo 1 > /sys/kernel/debug/dri/0/i915_wedged" when the display is not frozen, I only get the following in dmesg, and the system keeps working normally:
[  323.441616] [drm] Manually setting wedged to 1
[  323.441622] [drm] capturing error event; look for more information in /sys/class/drm/card0/error
[  348.955655] [drm] Manually setting wedged to 0

Is it to be expected that an "userspace hang" will escalate into a failed reset when setting i915_wedged to 1, without anything being actually wrong at the kernel side, at least at first?
> I'd suggest looking at the stacktraces of the usual suspects and see who
> is waiting upon whom, or if there is a more obvious lockup. Then begin
> the painful process of tracing the interoperation of those two processes
> to try and catch the breakdown.
> -Chris
>
I think Xorg is one of the "usual suspects". Should gnome-shell be one too? This is a Fedora 18 desktop with gnome-shell as installed from the DVD.