Created attachment 140418 [details] [review]
drm/amdgpu: Verify root PD is mapped into kernel address space.

dwagner, please try this patch. Fixes the issue for me and I observed no
suspend/resume issues.

Christian, please take a look at the patch, problem was that in
amdgpu_vm_update_directories the parent BO didn't have a kernel mapping and so
later inside amdgpu_vm_cpu_set_ptes 
pe += (unsigned long)amdgpu_bo_kptr(bo); would equal to  0000000000002000 since 
parent amdgpu_bo_kptr woudld return NULL. The parent was the root PD. 

This was still working in 67b8d5c Linus Torvalds      7 weeks ago    Linux
4.17-rc5   (tag: v4.17-rc5) but I wasn't able to exactly pinpoint which change
broke it. I am not sure my fix is the right one so please advise.