---

yaml
---
r: 356487
b: refs/heads/master
c: 10316b3
h: refs/heads/master
i:
  356485: 59a7c02
  356483: b3615d5
  356479: d882709
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: d778df51c09264076fe0208c099ef7d428f21790
+refs/heads/master: 10316b313cbde4b778c3d1b4b2fe2adbcbe84a48

trunk/mm/vmscan.c

@@ -1656,7 +1656,6 @@ static void get_scan_count(struct lruvec *lruvec, struct scan_control *sc,
 	struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat;
 	u64 fraction[2], denominator;
 	enum lru_list lru;
-	int noswap = 0;
 	bool force_scan = false;
 	struct zone *zone = lruvec_zone(lruvec);
 
@@ -1677,13 +1676,38 @@ static void get_scan_count(struct lruvec *lruvec, struct scan_control *sc,
 
 	/* If we have no swap space, do not bother scanning anon pages. */
 	if (!sc->may_swap || (nr_swap_pages <= 0)) {
-		noswap = 1;
 		fraction[0] = 0;
 		fraction[1] = 1;
 		denominator = 1;
 		goto out;
 	}
 
+	/*
+	 * Global reclaim will swap to prevent OOM even with no
+	 * swappiness, but memcg users want to use this knob to
+	 * disable swapping for individual groups completely when
+	 * using the memory controller's swap limit feature would be
+	 * too expensive.
+	 */
+	if (!global_reclaim(sc) && !vmscan_swappiness(sc)) {
+		fraction[0] = 0;
+		fraction[1] = 1;
+		denominator = 1;
+		goto out;
+	}
+
+	/*
+	 * Do not apply any pressure balancing cleverness when the
+	 * system is close to OOM, scan both anon and file equally
+	 * (unless the swappiness setting disagrees with swapping).
+	 */
+	if (!sc->priority && vmscan_swappiness(sc)) {
+		fraction[0] = 1;
+		fraction[1] = 1;
+		denominator = 1;
+		goto out;
+	}
+
 	anon  = get_lru_size(lruvec, LRU_ACTIVE_ANON) +
 		get_lru_size(lruvec, LRU_INACTIVE_ANON);
 	file  = get_lru_size(lruvec, LRU_ACTIVE_FILE) +
@@ -1765,13 +1789,10 @@ static void get_scan_count(struct lruvec *lruvec, struct scan_control *sc,
 		unsigned long scan;
 
 		size = get_lru_size(lruvec, lru);
-		if (sc->priority || noswap || !vmscan_swappiness(sc)) {
-			scan = size >> sc->priority;
-			if (!scan && force_scan)
-				scan = min(size, SWAP_CLUSTER_MAX);
-			scan = div64_u64(scan * fraction[file], denominator);
-		} else
-			scan = size;
+		scan = size >> sc->priority;
+		if (!scan && force_scan)
+			scan = min(size, SWAP_CLUSTER_MAX);
+		scan = div64_u64(scan * fraction[file], denominator);
 		nr[lru] = scan;
 	}
 }