Bad rss-counter state from drm/ttm, drm/vmwgfx: Support huge TTM pagefaults

Alex Xu (Hello71)
2020-04-06T19:51:36Z

Using 314b658 with amdgpu, starting sway and firefox causes "BUG: Bad
rss-counter state" and "BUG: non-zero pgtables_bytes on freeing mm" to
start filling dmesg, and then closing programs causes more BUGs and
hangs, and then everything grinds to a halt (can't start more programs,
can't even reboot through systemd).

Using master and reverting that branch up to that point fixes the
problem.

I'm using a Ryzen 1600 and AMD Radeon RX 480 on an ASRock B450 Pro4
board with IOMMU enabled.