I've also got rid of the horrible populate API, and integrated nonlinear pages
properly with the page fault path.
Downside is that this adds one more vector through which the buffered write
deadlock can occur. However this is just a very tiny one (pte being unmapped
for reclaim), compared to all the other ways that deadlock can occur (unmap,
reclaim, truncate, invalidate). I doubt it will be noticable. At any rate, it
is better than data corruption.
I hope these can get merged (at least into -mm) soon.