mm: vmscan: fix inappropriate zone congestion clearing

[~andy/linux] / mm / vmscan.c

diff --git a/mm/vmscan.c b/mm/vmscan.c
index cbf84e152f043c82b15d754a9f8c2c4c50866488..b7ed37675644ce7734946bfe5d2e2cfdc7f08fbc 100644 (file)
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2414,6 +2414,19 @@ static void age_active_anon(struct zone *zone, struct scan_control *sc)
        } while (memcg);
 }
 
+static bool zone_balanced(struct zone *zone, int order,
+                         unsigned long balance_gap, int classzone_idx)
+{
+       if (!zone_watermark_ok_safe(zone, order, high_wmark_pages(zone) +
+                                   balance_gap, classzone_idx, 0))
+               return false;
+
+       if (COMPACTION_BUILD && order && !compaction_suitable(zone, order))
+               return false;
+
+       return true;
+}
+
 /*
  * pgdat_balanced is used when checking if a node is balanced for high-order
  * allocations. Only zones that meet watermarks and are in a zone allowed
@@ -2492,8 +2505,7 @@ static bool prepare_kswapd_sleep(pg_data_t *pgdat, int order, long remaining,
                        continue;
                }
 
-               if (!zone_watermark_ok_safe(zone, order, high_wmark_pages(zone),
-                                                       i, 0))
+               if (!zone_balanced(zone, order, 0, i))
                        all_zones_ok = false;
                else
                        balanced += zone->present_pages;
@@ -2602,8 +2614,7 @@ loop_again:
                                break;
                        }
 
-                       if (!zone_watermark_ok_safe(zone, order,
-                                       high_wmark_pages(zone), 0, 0)) {
+                       if (!zone_balanced(zone, order, 0, 0)) {
                                end_zone = i;
                                break;
                        } else {
@@ -2679,9 +2690,8 @@ loop_again:
                                testorder = 0;
 
                        if ((buffer_heads_over_limit && is_highmem_idx(i)) ||
-                                   !zone_watermark_ok_safe(zone, testorder,
-                                       high_wmark_pages(zone) + balance_gap,
-                                       end_zone, 0)) {
+                           !zone_balanced(zone, testorder,
+                                          balance_gap, end_zone)) {
                                shrink_zone(zone, &sc);
 
                                reclaim_state->reclaimed_slab = 0;
@@ -2708,8 +2718,7 @@ loop_again:
                                continue;
                        }
 
-                       if (!zone_watermark_ok_safe(zone, testorder,
-                                       high_wmark_pages(zone), end_zone, 0)) {
+                       if (!zone_balanced(zone, testorder, 0, end_zone)) {
                                all_zones_ok = 0;
                                /*
                                 * We are still under min water mark.  This
@@ -2814,29 +2823,10 @@ out:
                        if (!populated_zone(zone))
                                continue;
 
-                       if (zone->all_unreclaimable &&
-                           sc.priority != DEF_PRIORITY)
-                               continue;
-
-                       /* Would compaction fail due to lack of free memory? */
-                       if (COMPACTION_BUILD &&
-                           compaction_suitable(zone, order) == COMPACT_SKIPPED)
-                               goto loop_again;
-
-                       /* Confirm the zone is balanced for order-0 */
-                       if (!zone_watermark_ok(zone, 0,
-                                       high_wmark_pages(zone), 0, 0)) {
-                               order = sc.order = 0;
-                               goto loop_again;
-                       }
-
                        /* Check if the memory needs to be defragmented. */
                        if (zone_watermark_ok(zone, order,
                                    low_wmark_pages(zone), *classzone_idx, 0))
                                zones_need_compaction = 0;
-
-                       /* If balanced, clear the congested flag */
-                       zone_clear_flag(zone, ZONE_CONGESTED);
                }
 
                if (zones_need_compaction)