[CRIU] [RFC PATCH] Try to include userfaultfd with criu

[adrian at lisas.de]

This is the code of my current attempt to use userfaultfd
with criu.

For my minimal test case it seems to work so far. It still needs
a lot of polish and far from being reading for inclusion, but I
wanted to get the current status published as a basis for discussion.

Especially for the remote lazy restore I am waiting on the image-cache
and image-proxy changes as those seem to be good basis for what I want
to do.

I am open to any suggestion how to implement this better.

Also at: https://github.com/adrianreber/criu/tree/uffd

		Adrian