mm: remove unused pgdat->inactive_ratio

Since commit 59dc76b0d4df ("mm: vmscan: reduce size of inactive file
list") 'pgdat->inactive_ratio' is not used, except for printing
"node_inactive_ratio: 0" in /proc/zoneinfo output.

Remove it.

Link: http://lkml.kernel.org/r/20171003152611.27483-1-aryabinin@virtuozzo.com
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/mmzone.h

@@ -712,12 +712,6 @@ typedef struct pglist_data {
 	/* Fields commonly accessed by the page reclaim scanner */
 	struct lruvec		lruvec;
 
-	/*
-	 * The target ratio of ACTIVE_ANON to INACTIVE_ANON pages on
-	 * this node's LRU.  Maintained by the pageout code.
-	 */
-	unsigned int inactive_ratio;
-
 	unsigned long		flags;
 
 	ZONE_PADDING(_pad2_)

mm/vmscan.c

@@ -2082,7 +2082,7 @@ static void shrink_active_list(unsigned long nr_to_scan,
  * If that fails and refaulting is observed, the inactive list grows.
  *
  * The inactive_ratio is the target ratio of ACTIVE to INACTIVE pages
- * on this LRU, maintained by the pageout code. A zone->inactive_ratio
+ * on this LRU, maintained by the pageout code. An inactive_ratio
  * of 3 means 3:1 or 25% of the pages are kept on the inactive list.
  *
  * total     target    max

mm/vmstat.c

@@ -1564,11 +1564,9 @@ static void zoneinfo_show_print(struct seq_file *m, pg_data_t *pgdat,
 	}
 	seq_printf(m,
 		   "\n  node_unreclaimable:  %u"
-		   "\n  start_pfn:           %lu"
-		   "\n  node_inactive_ratio: %u",
+		   "\n  start_pfn:           %lu",
 		   pgdat->kswapd_failures >= MAX_RECLAIM_RETRIES,
-		   zone->zone_start_pfn,
-		   zone->zone_pgdat->inactive_ratio);
+		   zone->zone_start_pfn);
 	seq_putc(m, '\n');
 }