Created attachment 145779 [details]
results of 'cat /sys/class/drm/card0/error > error', 'dmesg > dmesg' and 'uname -a' > uname
I saw below text in dmesg, so as requested, I am filing a bug report.
>> GPU HANG: ecode 9:2:0xfffffffe, in systemd-logind , hang on bcs0
>> GPU hangs can indicate a bug anywhere in the entire gfx stack, including userspace. Please file a _new_ bug report on bugs.freedesktop.org against DRI -> DRM/Intel drm/i915 developers can then reassign to the right component if it's not a kernel issue. The gpu crash dump is required to analyze gpu hangs, so please always attach it. GPU crash dump saved to /sys/class/drm/card0/error
I saw no symptoms aside of the dmesg report. On the user side everything seems OK.
So far, this is a single occurrence.
As you can see in dmesg log, please also note that the kernel was "tainted" because I loaded a network module (no public release of that module available).
Huh, an unterminated batch buffer. GPU overran into the wrong batch and exploded.