[Intel-gfx] [Regression] BUG: unable to handle kernel NULL pointer dereference

[Andrey Skvortsov]

On 28 Feb, Chris Wilson wrote:
> On Sat, Feb 28, 2015 at 03:20:37PM +0300, Andrey Skvortsov wrote:
> > Unfortunately this is not the last bug, that breaks i915/drm working
> > on my laptop. Sometimes system successfully loads with couple warnings mentioned in
> > previous mail:
> > 
> > [   26.922953] WARNING: CPU: 1 PID: 767 at drivers/gpu/drm/i915/i915_gem.c:4525 i915_gem_free_object+0x13f/0x288 [i915]()
> > [   26.922954] WARN_ON(obj->frontbuffer_bits)
> 
> That's inocuous, but for the serious hang, you may want to try
> video=SVIDEO-1:d on the kernel commandline to workaround the hang. (Check
> /sys/class/drm/card/ for the actual name of the connector for TV). I
> think Ville mentioned he was looking/looked at the atomic-vs-load_detect
> changes that is at the heart of the issue here. (Admittedly he did say
> it was worthy of a drink or two.)
> -Chris

Thank you for the help. I've tried to add to the kernel command line
'video=card0-SVIDEO-1:d video=card0-VGA-1:d'. But despite of that
kernel crashes with 'BUG: unable to handle kernel NULL pointer
dereference at' occasionally.

-- 
Best regards,
Andrey Skvortsov



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