mm: show node_pages_scanned per node, not zone

The node_pages_scanned represents the number of scanned pages of node
for reclaim so it's pointless to show it as kilobytes.

As well, node_pages_scanned is per-node value, not per-zone.

This patch changes node_pages_scanned per-zone-killobytes with
per-node-count.

[minchan@kernel.org: fix node_pages_scanned]
  Link: http://lkml.kernel.org/r/20160716101431.GA10305@bbox
Link: http://lkml.kernel.org/r/1468588165-12461-5-git-send-email-mgorman@techsingularity.net
Signed-off-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/page_alloc.c

@@ -4313,6 +4313,7 @@ void show_free_areas(unsigned int filter)
 #endif
 			" writeback_tmp:%lukB"
 			" unstable:%lukB"
+			" pages_scanned:%lu"
 			" all_unreclaimable? %s"
 			"\n",
 			pgdat->node_id,
@@ -4335,6 +4336,7 @@ void show_free_areas(unsigned int filter)
 			K(node_page_state(pgdat, NR_SHMEM)),
 			K(node_page_state(pgdat, NR_WRITEBACK_TEMP)),
 			K(node_page_state(pgdat, NR_UNSTABLE_NFS)),
+			node_page_state(pgdat, NR_PAGES_SCANNED),
 			!pgdat_reclaimable(pgdat) ? "yes" : "no");
 	}
 
@@ -4365,7 +4367,6 @@ void show_free_areas(unsigned int filter)
 			" free_pcp:%lukB"
 			" local_pcp:%ukB"
 			" free_cma:%lukB"
-			" node_pages_scanned:%lu"
 			"\n",
 			zone->name,
 			K(zone_page_state(zone, NR_FREE_PAGES)),
@@ -4383,8 +4384,7 @@ void show_free_areas(unsigned int filter)
 			K(zone_page_state(zone, NR_BOUNCE)),
 			K(free_pcp),
 			K(this_cpu_read(zone->pageset->pcp.count)),
-			K(zone_page_state(zone, NR_FREE_CMA_PAGES)),
-			K(node_page_state(zone->zone_pgdat, NR_PAGES_SCANNED)));
+			K(zone_page_state(zone, NR_FREE_CMA_PAGES)));
 		printk("lowmem_reserve[]:");
 		for (i = 0; i < MAX_NR_ZONES; i++)
 			printk(" %ld", zone->lowmem_reserve[i]);