[LSF/MM/BPF TOPIC] Handling of VMAs

Currently VMAs are split, shrunk, merged, moved, copy on write, and copied all
in an attempt to do a relatively simple task of keeping track of a list of
memory segments.  There is a cache, a tree, and a linked list of VMAs in each
MM.  There is also a reverse mapping from PTEs to VMAs.

We have arrived to a point where there is enough lock contention and
complications on handling these seemingly simple data structures that it may be
time to rethink how a VMA is tracked and modified.

I'll have more patches closer to the conference.

Thanks,
Liam