[PATCH] mm/migrate.c: return valid zone for wakeup_kswapd from migrate_balanced_pgdat()

[Wei Yang]

To wakeup kswapd, we need to iterate pgdat->node_zones and get the
proper zone. While this work has already been done in
migrate_balanced_pgdat().

Let's return the valid zone directly instead of do the iteration again.

Signed-off-by: Wei Yang <richard.weiyang@xxxxxxxxx>
---
 mm/migrate.c | 21 ++++++++-------------
 1 file changed, 8 insertions(+), 13 deletions(-)

diff --git a/mm/migrate.c b/mm/migrate.c
index 5adc55b5347c..b086bd781956 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1973,7 +1973,7 @@ SYSCALL_DEFINE6(move_pages, pid_t, pid, unsigned long, nr_pages,
  * Returns true if this is a safe migration target node for misplaced NUMA
  * pages. Currently it only checks the watermarks which is crude.
  */
-static bool migrate_balanced_pgdat(struct pglist_data *pgdat,
+static struct zone *migrate_balanced_pgdat(struct pglist_data *pgdat,
 				   unsigned long nr_migrate_pages)
 {
 	int z;
@@ -1985,14 +1985,13 @@ static bool migrate_balanced_pgdat(struct pglist_data *pgdat,
 			continue;
 
 		/* Avoid waking kswapd by allocating pages_to_migrate pages. */
-		if (!zone_watermark_ok(zone, 0,
+		if (zone_watermark_ok(zone, 0,
 				       high_wmark_pages(zone) +
 				       nr_migrate_pages,
 				       ZONE_MOVABLE, 0))
-			continue;
-		return true;
+			return zone;
 	}
-	return false;
+	return NULL;
 }
 
 static struct page *alloc_misplaced_dst_page(struct page *page,
@@ -2032,6 +2031,7 @@ static int numamigrate_isolate_page(pg_data_t *pgdat, struct page *page)
 	int page_lru;
 	int nr_pages = thp_nr_pages(page);
 	int order = compound_order(page);
+	struct zone *zone;
 
 	VM_BUG_ON_PAGE(order && !PageTransHuge(page), page);
 
@@ -2040,16 +2040,11 @@ static int numamigrate_isolate_page(pg_data_t *pgdat, struct page *page)
 		return 0;
 
 	/* Avoid migrating to a node that is nearly full */
-	if (!migrate_balanced_pgdat(pgdat, nr_pages)) {
-		int z;
-
+	if ((zone = migrate_balanced_pgdat(pgdat, nr_pages))) {
 		if (!(sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING))
 			return 0;
-		for (z = pgdat->nr_zones - 1; z >= 0; z--) {
-			if (managed_zone(pgdat->node_zones + z))
-				break;
-		}
-		wakeup_kswapd(pgdat->node_zones + z, 0, order, ZONE_MOVABLE);
+
+		wakeup_kswapd(zone, 0, order, ZONE_MOVABLE);
 		return 0;
 	}
 
-- 
2.33.1


>Best Regards,
>Huang, Ying

-- 
Wei Yang
Help you, Help me