I was his advisor on that thesis so I got to watch it roll out as it
happened.

uvm replaced the machvm in netbsd.

For a time, Chuck set it up to run in parallel with the existing VM. You
could start a process and pick which vm it used. For a while, it defaulted
to the existing one. Then, at some point, it defaulted to uvm. Then, at
some point, the old one was removed.

more here:

http://www.netbsd.org/docs/kernel/uvm.html

via search terms
uvm replaces machvm netbsd

chuck was a long time contributor to netbsd IIRC, but last time we talked,
he was using Linux.

ron