__alloc_pages currently starts shooting if page reclaim has failed to free up
swap_cluster_max pages in one run through the priorities.  This is not always
a good indicator on its own, so make use of the all_unreclaimable logic as
well: don't consider going OOM until all zones we're interested in are
unreclaimable.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>