relay: nopage

Convert relay from nopage to fault.
Remove redundant vma range checks.
Switch from OOM to SIGBUS if the resource is not available.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Tom Zanussi <zanussi@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>