mm, vmscan: simplify the logic deciding whether kswapd sleeps

kswapd goes through some complex steps trying to figure out if it should
stay awake based on the classzone_idx and the requested order.  It is
unnecessarily complex and passes in an invalid classzone_idx to
balance_pgdat().  What matters most of all is whether a larger order has
been requsted and whether kswapd successfully reclaimed at the previous
order.  This patch irons out the logic to check just that and the end
result is less headache inducing.

Link: http://lkml.kernel.org/r/1467970510-21195-10-git-send-email-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Rik van Riel <riel@surriel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 35e2d0f9d44f..81586410c59c 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -6039,7 +6039,7 @@ void __paginginit free_area_init_node(int nid, unsigned long *zones_size,
         unsigned long end_pfn = 0;
 
         /* pg_data_t should be reset to zero when it's allocated */
-        WARN_ON(pgdat->nr_zones || pgdat->classzone_idx);
+        WARN_ON(pgdat->nr_zones || pgdat->kswapd_classzone_idx);
 
         reset_deferred_meminit(pgdat);
         pgdat->node_id = nid;