Earlier patches focused on having direct reclaim and kswapd use data that
is node-centric for reclaiming but shrink_node() itself still uses too much
zone information. This patch removes unnecessary zone-based information
with the most important decision being whether to continue reclaim or
not. Some memcg APIs are adjusted as a result even though memcg itself
still uses some zone information.
Signed-off-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>