---

yaml
---
r: 292638
b: refs/heads/master
c: cc715d9
h: refs/heads/master
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: ce1744f4ed20ca873360e54502f8a71564ef7cc6
+refs/heads/master: cc715d99e529d470dde2f33a6614f255adea71f3

trunk/mm/vmscan.c

@@ -1642,18 +1642,6 @@ static void move_active_pages_to_lru(struct zone *zone,
 	unsigned long pgmoved = 0;
 	struct page *page;
 
-	if (buffer_heads_over_limit) {
-		spin_unlock_irq(&zone->lru_lock);
-		list_for_each_entry(page, list, lru) {
-			if (page_has_private(page) && trylock_page(page)) {
-				if (page_has_private(page))
-					try_to_release_page(page, 0);
-				unlock_page(page);
-			}
-		}
-		spin_lock_irq(&zone->lru_lock);
-	}
-
 	while (!list_empty(list)) {
 		struct lruvec *lruvec;
 
@@ -1735,6 +1723,14 @@ static void shrink_active_list(unsigned long nr_to_scan,
 			continue;
 		}
 
+		if (unlikely(buffer_heads_over_limit)) {
+			if (page_has_private(page) && trylock_page(page)) {
+				if (page_has_private(page))
+					try_to_release_page(page, 0);
+				unlock_page(page);
+			}
+		}
+
 		if (page_referenced(page, 0, mz->mem_cgroup, &vm_flags)) {
 			nr_rotated += hpage_nr_pages(page);
 			/*
@@ -2238,6 +2234,14 @@ static bool shrink_zones(int priority, struct zonelist *zonelist,
 	unsigned long nr_soft_scanned;
 	bool aborted_reclaim = false;
 
+	/*
+	 * If the number of buffer_heads in the machine exceeds the maximum
+	 * allowed level, force direct reclaim to scan the highmem zone as
+	 * highmem pages could be pinning lowmem pages storing buffer_heads
+	 */
+	if (buffer_heads_over_limit)
+		sc->gfp_mask |= __GFP_HIGHMEM;
+
 	for_each_zone_zonelist_nodemask(zone, z, zonelist,
 					gfp_zone(sc->gfp_mask), sc->nodemask) {
 		if (!populated_zone(zone))
@@ -2727,6 +2731,17 @@ static unsigned long balance_pgdat(pg_data_t *pgdat, int order,
 			 */
 			age_active_anon(zone, &sc, priority);
 
+			/*
+			 * If the number of buffer_heads in the machine
+			 * exceeds the maximum allowed level and this node
+			 * has a highmem zone, force kswapd to reclaim from
+			 * it to relieve lowmem pressure.
+			 */
+			if (buffer_heads_over_limit && is_highmem_idx(i)) {
+				end_zone = i;
+				break;
+			}
+
 			if (!zone_watermark_ok_safe(zone, order,
 					high_wmark_pages(zone), 0, 0)) {
 				end_zone = i;
@@ -2802,7 +2817,8 @@ static unsigned long balance_pgdat(pg_data_t *pgdat, int order,
 						COMPACT_SKIPPED)
 				testorder = 0;
 
-			if (!zone_watermark_ok_safe(zone, testorder,
+			if ((buffer_heads_over_limit && is_highmem_idx(i)) ||
+				    !zone_watermark_ok_safe(zone, order,
 					high_wmark_pages(zone) + balance_gap,
 					end_zone, 0)) {
 				shrink_zone(priority, zone, &sc);