mm: migrate: Account a transhuge page properly when rate limiting

If there is excessive migration due to NUMA balancing it gets rate
limited. It does this by counting the number of pages it has migrated
recently but counts a transhuge page as 1 page. Account for it properly.

Signed-off-by: Mel Gorman <mgorman@suse.de>

mm/migrate.c

@@ -1492,7 +1492,7 @@ bool migrate_ratelimited(int node)
 }
 
 /* Returns true if the node is migrate rate-limited after the update */
-bool numamigrate_update_ratelimit(pg_data_t *pgdat)
+bool numamigrate_update_ratelimit(pg_data_t *pgdat, unsigned long nr_pages)
 {
 	bool rate_limited = false;
 
@@ -1510,7 +1510,7 @@ bool numamigrate_update_ratelimit(pg_data_t *pgdat)
 	if (pgdat->numabalancing_migrate_nr_pages > ratelimit_pages)
 		rate_limited = true;
 	else
-		pgdat->numabalancing_migrate_nr_pages++;
+		pgdat->numabalancing_migrate_nr_pages += nr_pages;
 	spin_unlock(&pgdat->numabalancing_migrate_lock);
 	
 	return rate_limited;
@@ -1579,7 +1579,7 @@ int migrate_misplaced_page(struct page *page, int node)
 	 * Optimal placement is no good if the memory bus is saturated and
 	 * all the time is being spent migrating!
 	 */
-	if (numamigrate_update_ratelimit(pgdat)) {
+	if (numamigrate_update_ratelimit(pgdat, 1)) {
 		put_page(page);
 		goto out;
 	}
@@ -1630,7 +1630,7 @@ int migrate_misplaced_transhuge_page(struct mm_struct *mm,
 	 * Optimal placement is no good if the memory bus is saturated and
 	 * all the time is being spent migrating!
 	 */
-	if (numamigrate_update_ratelimit(pgdat))
+	if (numamigrate_update_ratelimit(pgdat, HPAGE_PMD_NR))
 		goto out_dropref;
 
 	new_page = alloc_pages_node(node,