A freeze occured while working with the laptop:

uname -r
4.16.0-rc1-085145ebf0e9

[20516.321517] [drm:amdgpu_job_timedout [amdgpu]] *ERROR* ring gfx timeout,
last signaled seq=448660, last emitted seq=448663
[20516.321526] [drm] No hardware hang detected. Did some blocks stall?