(In reply to Andrey Grodzovsky from comment #6)
> Verify you are using latest AMD firmware and up to date MESA/LLVM

Firmware:

pacman -Q linux-firmware
linux-firmware 20180606.d114732-1

ll  /usr/lib/firmware/amdgpu/vega10_vce.bin
-rw-r--r-- 1 root root 165344 Jun  7 08:01
/usr/lib/firmware/amdgpu/vega10_vce.bin

MESA:

pacman -Q mesa
mesa 18.1.2-1

LLVM:
pacman -Q llvm-libs
llvm-libs 6.0.0-4

Is this new enough?

BTW: In a forum somebody asked what the dmesg output on crash looked like if I
enabled amdgpu.gpu_recovery=1 - the result is a few lines more of output, but
still a fatal system crash:

Jun 26 00:50:09 ryzen kernel: [drm:amdgpu_job_timedout [amdgpu]] *ERROR* ring
gfx timeout, last signaled seq=12277, last emitted seq=12279
Jun 26 00:50:09 ryzen kernel: [drm] IP block:gmc_v8_0 is hung!
Jun 26 00:50:09 ryzen kernel: [drm] IP block:gfx_v8_0 is hung!
Jun 26 00:50:09 ryzen kernel: amdgpu 0000:0a:00.0: GPU reset begin!
Jun 26 00:50:15 ryzen kernel: [drm:drm_atomic_helper_wait_for_flip_done
[drm_kms_helper]] *ERROR* [CRTC:42:crtc-0] flip_done timed out
Jun 26 00:50:15 ryzen kernel: [drm:drm_atomic_helper_wait_for_dependencies
[drm_kms_helper]] *ERROR* [CRTC:42:crtc-0] flip_done timed out
Jun 26 00:50:25 ryzen kernel: [drm:drm_atomic_helper_wait_for_dependencies
[drm_kms_helper]] *ERROR* [PLANE:40:plane-4] flip_done timed out