Fix up active load balancing a bit so it doesn't get called when it shouldn't.
Reset the nr_balance_failed counter at more points where we have found
conditions to be balanced.  This reduces too aggressive active balancing seen
on some workloads.
Signed-off-by: NNick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>