while this may be more prevelent now, this has always been a problem.


i think we need some way to steal pages for contig allocations.  find
the largest segment that has owners you can steal from.  i'm not sure
about the details.  possibly a simple version that could still fail
would find r/o non-wired pages.  a more complete version that was
able to clean dirty pages in the largest otherwise clean segment would
be useful but it depends on the user being able to sleep...