Appears to be fixed with commit:
"drm/nv50-nvc0: make sure vma is definitely unmapped when destroying bo"
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
The immediate benefit of doing this is that on NV50 and up, the GPU
virtual address of any buffer is now constant, regardless of what
memtype they're placed in.
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>