mm: WIP, trying to avoid splitting is a mess.

mm: WIP, trying to avoid splitting is a mess.

If you split this VMA, then it is inserted into the tree.  Instead, we
try to create a dummy VMA and pass that along to handle freeing.  Unfortunately,
the hugetlb cases seem to require the file handle to be correctly processed
in the unmap_single_vma() call path.  There may be memory leaks in the cases
where we are not a hugetlb page, but I didn't see that.

The unfornate part is that we have to insert ourselves into the interval tree
when we try to do more with the VMA.

For now, let's just go back to something that is less of a mess

Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>