1 files changed, 53 insertions, 6 deletions

diff --git a/mm/vmscan.c b/mm/vmscan.c
index a6e65d024995..bbd194630c5b 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -932,6 +932,7 @@ static void shrink_active_list(unsigned long nr_pages, struct zone *zone,
                 long mapped_ratio;
                 long distress;
                 long swap_tendency;
+                long imbalance;
 
                 if (zone_is_near_oom(zone))
                         goto force_reclaim_mapped;
@@ -967,6 +968,46 @@ static void shrink_active_list(unsigned long nr_pages, struct zone *zone,
                 swap_tendency = mapped_ratio / 2 + distress + sc->swappiness;
 
                 /*
+                 * If there's huge imbalance between active and inactive
+                 * (think active 100 times larger than inactive) we should
+                 * become more permissive, or the system will take too much
+                 * cpu before it start swapping during memory pressure.
+                 * Distress is about avoiding early-oom, this is about
+                 * making swappiness graceful despite setting it to low
+                 * values.
+                 *
+                 * Avoid div by zero with nr_inactive+1, and max resulting
+                 * value is vm_total_pages.
+                 */
+                imbalance  = zone_page_state(zone, NR_ACTIVE);
+                imbalance /= zone_page_state(zone, NR_INACTIVE) + 1;
+
+                /*
+                 * Reduce the effect of imbalance if swappiness is low,
+                 * this means for a swappiness very low, the imbalance
+                 * must be much higher than 100 for this logic to make
+                 * the difference.
+                 *
+                 * Max temporary value is vm_total_pages*100.
+                 */
+                imbalance *= (vm_swappiness + 1);
+                imbalance /= 100;
+
+                /*
+                 * If not much of the ram is mapped, makes the imbalance
+                 * less relevant, it's high priority we refill the inactive
+                 * list with mapped pages only in presence of high ratio of
+                 * mapped pages.
+                 *
+                 * Max temporary value is vm_total_pages*100.
+                 */
+                imbalance *= mapped_ratio;
+                imbalance /= 100;
+
+                /* apply imbalance feedback to swap_tendency */
+                swap_tendency += imbalance;
+
+                /*
                  * Now use this metric to decide whether to start moving mapped
                  * memory onto the inactive list.
                  */
@@ -1371,7 +1412,13 @@ loop_again:
                         temp_priority[i] = priority;
                         sc.nr_scanned = 0;
                         note_zone_scanning_priority(zone, priority);
-                        nr_reclaimed += shrink_zone(priority, zone, &sc);
+                        /*
+                         * We put equal pressure on every zone, unless one
+                         * zone has way too many pages free already.
+                         */
+                        if (!zone_watermark_ok(zone, order, 8*zone->pages_high,
+                                                end_zone, 0))
+                                nr_reclaimed += shrink_zone(priority, zone, &sc);
                         reclaim_state->reclaimed_slab = 0;
                         nr_slab = shrink_slab(sc.nr_scanned, GFP_KERNEL,
                                                 lru_pages);
@@ -1688,9 +1735,11 @@ static int __devinit cpu_callback(struct notifier_block *nfb,
 {
         pg_data_t *pgdat;
         cpumask_t mask;
+        int nid;
 
         if (action == CPU_ONLINE || action == CPU_ONLINE_FROZEN) {
-                for_each_online_pgdat(pgdat) {
+                for_each_node_state(nid, N_HIGH_MEMORY) {
+                        pgdat = NODE_DATA(nid);
                         mask = node_to_cpumask(pgdat->node_id);
                         if (any_online_cpu(mask) != NR_CPUS)
                                 /* One of our CPUs online: restore mask */
@@ -1727,7 +1776,7 @@ static int __init kswapd_init(void)
         int nid;
 
         swap_setup();
-        for_each_online_node(nid)
+        for_each_node_state(nid, N_HIGH_MEMORY)
                 kswapd_run(nid);
         hotcpu_notifier(cpu_callback, 0);
         return 0;
@@ -1847,7 +1896,6 @@ static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
 
 int zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
 {
-        cpumask_t mask;
         int node_id;
 
         /*
@@ -1884,8 +1932,7 @@ int zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
          * as wide as possible.
          */
         node_id = zone_to_nid(zone);
-        mask = node_to_cpumask(node_id);
-        if (!cpus_empty(mask) && node_id != numa_node_id())
+        if (node_state(node_id, N_CPU) && node_id != numa_node_id())
                 return 0;
         return __zone_reclaim(zone, gfp_mask, order);
 }