become children of the released resource's parent?  Should they be released
too?  Should we fail the release?

I bet we have no callers who expect this right now, but with
insert_resource() we may get some.  At the point where someone hits this
BUG we can figure out what semantics we want.
Signed-off-by: Matthew Wilcox <willy@parisc-linux.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>