[Intel-gfx] PROBLEM: i915 causes complete desktop freezes in 4.15-rc5

[Chris Wilson]

Quoting Alexandru Chirvasitu (2018-01-03 00:14:38)
> For comparison, here's another one produced by the same kernel, on the
> same laptop, but a different hard drive.
> 
> The OS was installed on a USB stick that I'd boot the laptop off
> of. Recently I started getting lags when copying to / from the stick,
> so I moved the OS to an external SSD.
> 
> Everything else stayed the same, and booting the same kernel resulted
> in the same type of freeze. 

I still have no explanation for how the use-after-free is possible here.
The list iteration and destruction are both guarded by the struct_mutex.

However, we have just pushed some extra assertions into drm-tip,
https://cgit.freedesktop.org/drm-tip If you could please compile and
test a kernel built using that branch and enable
CONFIG_DRM_I915_DEBUG_GEM (which depends on CONFIG_DRM_I915_WERROR). I'm
hoping that will catch the culprit in the act.
-Chris