(In reply to Christian König from comment #4)
> You can restrict that to changes to drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c.
> 
> The problem is that we use more dw than expected for clearing the page
> tables. No idea what exactly goes wrong, but bisecting the commit which
> introduced it would certainly help.

I'm sorry, but I will not be able to bisect this. Checkouts of relevant commits
don't boot and simple reverts do apply cleanly, but don't compile.