I tried out Sasha's suggestion. Note that *just* taking
aac6db75a9 ("vfio/pci: Use unmap_mapping_range()") is not sufficient, we also
need b7c5e64fec ("vfio: Create vfio_fs_type with inode per device").
But, the good news is both of those apply more or less cleanly to 6.6. And, at
least under a very basic test which exercises VFIO memory mapping, things seem
to work properly with that change.
I would agree with Leah that these seem a bit big to be stable fixes. But, I'm
encouraged by the fact that Sasha suggested taking them. If there are no big
objections (Alex? :) ) I can send the backport patches this week.
