---

yaml
---
r: 2446
b: refs/heads/master
c: 1e7e5a9
h: refs/heads/master
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 0c35bbadc59f5ed105c34471143eceb4c0dd9c95
+refs/heads/master: 1e7e5a9048b30c57ba1ddaa6cdf59b21b65cde99

trunk/include/linux/mmzone.h

@@ -149,6 +149,8 @@ struct zone {
 	 * as it fails a watermark_ok() in __alloc_pages?
 	 */
 	int			reclaim_pages;
+	/* A count of how many reclaimers are scanning this zone */
+	atomic_t		reclaim_in_progress;
 
 	/*
 	 * prev_priority holds the scanning priority for this zone.  It is

trunk/mm/page_alloc.c

@@ -1738,6 +1738,7 @@ static void __init free_area_init_core(struct pglist_data *pgdat,
 		zone->nr_scan_inactive = 0;
 		zone->nr_active = 0;
 		zone->nr_inactive = 0;
+		atomic_set(&zone->reclaim_in_progress, -1);
 		if (!size)
 			continue;
 

trunk/mm/vmscan.c

@@ -900,7 +900,9 @@ shrink_caches(struct zone **zones, struct scan_control *sc)
 		if (zone->all_unreclaimable && sc->priority != DEF_PRIORITY)
 			continue;	/* Let kswapd poll it */
 
+		atomic_inc(&zone->reclaim_in_progress);
 		shrink_zone(zone, sc);
+		atomic_dec(&zone->reclaim_in_progress);
 	}
 }
 
@@ -1111,7 +1113,9 @@ static int balance_pgdat(pg_data_t *pgdat, int nr_pages, int order)
 			sc.nr_reclaimed = 0;
 			sc.priority = priority;
 			sc.swap_cluster_max = nr_pages? nr_pages : SWAP_CLUSTER_MAX;
+			atomic_inc(&zone->reclaim_in_progress);
 			shrink_zone(zone, &sc);
+			atomic_dec(&zone->reclaim_in_progress);
 			reclaim_state->reclaimed_slab = 0;
 			nr_slab = shrink_slab(sc.nr_scanned, GFP_KERNEL,
 						lru_pages);
@@ -1354,9 +1358,15 @@ int zone_reclaim(struct zone *zone, unsigned int gfp_mask, unsigned int order)
 	else
 		sc.swap_cluster_max = SWAP_CLUSTER_MAX;
 
+	/* Don't reclaim the zone if there are other reclaimers active */
+	if (!atomic_inc_and_test(&zone->reclaim_in_progress))
+		goto out;
+
 	shrink_zone(zone, &sc);
 	total_reclaimed = sc.nr_reclaimed;
 
+ out:
+	atomic_dec(&zone->reclaim_in_progress);
 	return total_reclaimed;
 }