1 files changed, 15 insertions, 12 deletions

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 7889f583ced9..910e02c793ff 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -3644,19 +3644,18 @@ out:
 }
 
 /*
- * pgdat->kswapd_classzone_idx is the highest zone index that a recent
- * allocation request woke kswapd for. When kswapd has not woken recently,
- * the value is MAX_NR_ZONES which is not a valid index. This compares a
- * given classzone and returns it or the highest classzone index kswapd
- * was recently woke for.
+ * The pgdat->kswapd_classzone_idx is used to pass the highest zone index to be
+ * reclaimed by kswapd from the waker. If the value is MAX_NR_ZONES which is not
+ * a valid index then either kswapd runs for first time or kswapd couldn't sleep
+ * after previous reclaim attempt (node is still unbalanced). In that case
+ * return the zone index of the previous kswapd reclaim cycle.
  */
 static enum zone_type kswapd_classzone_idx(pg_data_t *pgdat,
-                                           enum zone_type classzone_idx)
+                                           enum zone_type prev_classzone_idx)
 {
         if (pgdat->kswapd_classzone_idx == MAX_NR_ZONES)
-                return classzone_idx;
-
-        return max(pgdat->kswapd_classzone_idx, classzone_idx);
+                return prev_classzone_idx;
+        return pgdat->kswapd_classzone_idx;
 }
 
 static void kswapd_try_to_sleep(pg_data_t *pgdat, int alloc_order, int reclaim_order,
@@ -3797,7 +3796,7 @@ kswapd_try_sleep:
 
                 /* Read the new order and classzone_idx */
                 alloc_order = reclaim_order = pgdat->kswapd_order;
-                classzone_idx = kswapd_classzone_idx(pgdat, 0);
+                classzone_idx = kswapd_classzone_idx(pgdat, classzone_idx);
                 pgdat->kswapd_order = 0;
                 pgdat->kswapd_classzone_idx = MAX_NR_ZONES;
 
@@ -3851,8 +3850,12 @@ void wakeup_kswapd(struct zone *zone, gfp_t gfp_flags, int order,
         if (!cpuset_zone_allowed(zone, gfp_flags))
                 return;
         pgdat = zone->zone_pgdat;
-        pgdat->kswapd_classzone_idx = kswapd_classzone_idx(pgdat,
-                                                           classzone_idx);
+
+        if (pgdat->kswapd_classzone_idx == MAX_NR_ZONES)
+                pgdat->kswapd_classzone_idx = classzone_idx;
+        else
+                pgdat->kswapd_classzone_idx = max(pgdat->kswapd_classzone_idx,
+                                                  classzone_idx);
         pgdat->kswapd_order = max(pgdat->kswapd_order, order);
         if (!waitqueue_active(&pgdat->kswapd_wait))
                 return;