2 files changed, 92 insertions, 5 deletions

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 40169f0b7e9e..3c0f69ded6b5 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -724,6 +724,14 @@ int zone_watermark_ok(struct zone *z, int order, unsigned long mark,
         return 1;
 }
 
+static inline int
+should_reclaim_zone(struct zone *z, unsigned int gfp_mask)
+{
+        if (!z->reclaim_pages)
+                return 0;
+        return 1;
+}
+
 /*
  * This is the 'heart' of the zoned buddy allocator.
  */
@@ -760,17 +768,32 @@ __alloc_pages(unsigned int __nocast gfp_mask, unsigned int order,
 
         classzone_idx = zone_idx(zones[0]);
 
- restart:
+restart:
         /* Go through the zonelist once, looking for a zone with enough free */
         for (i = 0; (z = zones[i]) != NULL; i++) {
-
-                if (!zone_watermark_ok(z, order, z->pages_low,
-                                       classzone_idx, 0, 0))
-                        continue;
+                int do_reclaim = should_reclaim_zone(z, gfp_mask);
 
                 if (!cpuset_zone_allowed(z))
                         continue;
 
+                /*
+                 * If the zone is to attempt early page reclaim then this loop
+                 * will try to reclaim pages and check the watermark a second
+                 * time before giving up and falling back to the next zone.
+                 */
+zone_reclaim_retry:
+                if (!zone_watermark_ok(z, order, z->pages_low,
+                                       classzone_idx, 0, 0)) {
+                        if (!do_reclaim)
+                                continue;
+                        else {
+                                zone_reclaim(z, gfp_mask, order);
+                                /* Only try reclaim once */
+                                do_reclaim = 0;
+                                goto zone_reclaim_retry;
+                        }
+                }
+
                 page = buffered_rmqueue(z, order, gfp_mask);
                 if (page)
                         goto got_pg;
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 6379ddbffd9b..7da846960d8a 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1323,3 +1323,67 @@ static int __init kswapd_init(void)
 }
 
 module_init(kswapd_init)
+
+
+/*
+ * Try to free up some pages from this zone through reclaim.
+ */
+int zone_reclaim(struct zone *zone, unsigned int gfp_mask, unsigned int order)
+{
+        struct scan_control sc;
+        int nr_pages = 1 << order;
+        int total_reclaimed = 0;
+
+        /* The reclaim may sleep, so don't do it if sleep isn't allowed */
+        if (!(gfp_mask & __GFP_WAIT))
+                return 0;
+        if (zone->all_unreclaimable)
+                return 0;
+
+        sc.gfp_mask = gfp_mask;
+        sc.may_writepage = 0;
+        sc.may_swap = 0;
+        sc.nr_mapped = read_page_state(nr_mapped);
+        sc.nr_scanned = 0;
+        sc.nr_reclaimed = 0;
+        /* scan at the highest priority */
+        sc.priority = 0;
+
+        if (nr_pages > SWAP_CLUSTER_MAX)
+                sc.swap_cluster_max = nr_pages;
+        else
+                sc.swap_cluster_max = SWAP_CLUSTER_MAX;
+
+        shrink_zone(zone, &sc);
+        total_reclaimed = sc.nr_reclaimed;
+
+        return total_reclaimed;
+}
+
+asmlinkage long sys_set_zone_reclaim(unsigned int node, unsigned int zone,
+                                     unsigned int state)
+{
+        struct zone *z;
+        int i;
+
+        if (node >= MAX_NUMNODES || !node_online(node))
+                return -EINVAL;
+
+        /* This will break if we ever add more zones */
+        if (!(zone & (1<<ZONE_DMA|1<<ZONE_NORMAL|1<<ZONE_HIGHMEM)))
+                return -EINVAL;
+
+        for (i = 0; i < MAX_NR_ZONES; i++) {
+                if (!(zone & 1<<i))
+                        continue;
+
+                z = &NODE_DATA(node)->node_zones[i];
+
+                if (state)
+                        z->reclaim_pages = 1;
+                else
+                        z->reclaim_pages = 0;
+        }
+
+        return 0;
+}