Created attachment 143678 [details]
kernel log

Vega 64, Linux 5.0, mesa git 1ea42894c70, llvm git
https://github.com/llvm-mirror/llvm/commit/d8706fcd747

Unfortunately hard to reproduce:
Play custom maps in warcraft 3 (started with -opengl) in wine (4.1) for a few
hours and maybe it'll happen.

Interestingly amdgpu thinks kwin is the culprit:

Mär 14 23:58:30 c-pc kernel: [drm:amdgpu_job_timedout [amdgpu]] *ERROR* ring
gfx timeout, signaled seq=5170371, emitted seq=5170373
Mär 14 23:58:30 c-pc kernel: [drm:amdgpu_job_timedout [amdgpu]] *ERROR* Process
information: process kwin_x11 pid 999 thread kwin_x11:cs0 pid 1396

I've also seen it say steam instead of kwin.

Other games do not seem to trigger this.