1 files changed, 37 insertions, 25 deletions

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 4f49535d4cd3..d036e59d302b 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2310,7 +2310,8 @@ static bool pgdat_balanced(pg_data_t *pgdat, unsigned long balanced_pages,
         for (i = 0; i <= classzone_idx; i++)
                 present_pages += pgdat->node_zones[i].present_pages;
 
-        return balanced_pages > (present_pages >> 2);
+        /* A special case here: if zone has no page, we think it's balanced */
+        return balanced_pages >= (present_pages >> 2);
 }
 
 /* is kswapd sleeping prematurely? */
@@ -2326,7 +2327,7 @@ static bool sleeping_prematurely(pg_data_t *pgdat, int order, long remaining,
                 return true;
 
         /* Check the watermark levels */
-        for (i = 0; i < pgdat->nr_zones; i++) {
+        for (i = 0; i <= classzone_idx; i++) {
                 struct zone *zone = pgdat->node_zones + i;
 
                 if (!populated_zone(zone))
@@ -2344,7 +2345,7 @@ static bool sleeping_prematurely(pg_data_t *pgdat, int order, long remaining,
                 }
 
                 if (!zone_watermark_ok_safe(zone, order, high_wmark_pages(zone),
-                                                        classzone_idx, 0))
+                                                        i, 0))
                         all_zones_ok = false;
                 else
                         balanced += zone->present_pages;
@@ -2451,7 +2452,6 @@ loop_again:
                         if (!zone_watermark_ok_safe(zone, order,
                                         high_wmark_pages(zone), 0, 0)) {
                                 end_zone = i;
-                                *classzone_idx = i;
                                 break;
                         }
                 }
@@ -2510,18 +2510,18 @@ loop_again:
                                 KSWAPD_ZONE_BALANCE_GAP_RATIO);
                         if (!zone_watermark_ok_safe(zone, order,
                                         high_wmark_pages(zone) + balance_gap,
-                                        end_zone, 0))
+                                        end_zone, 0)) {
                                 shrink_zone(priority, zone, &sc);
-                        reclaim_state->reclaimed_slab = 0;
-                        nr_slab = shrink_slab(&shrink, sc.nr_scanned, lru_pages);
-                        sc.nr_reclaimed += reclaim_state->reclaimed_slab;
-                        total_scanned += sc.nr_scanned;
 
-                        if (zone->all_unreclaimable)
-                                continue;
-                        if (nr_slab == 0 &&
-                            !zone_reclaimable(zone))
-                                zone->all_unreclaimable = 1;
+                                reclaim_state->reclaimed_slab = 0;
+                                nr_slab = shrink_slab(&shrink, sc.nr_scanned, lru_pages);
+                                sc.nr_reclaimed += reclaim_state->reclaimed_slab;
+                                total_scanned += sc.nr_scanned;
+
+                                if (nr_slab == 0 && !zone_reclaimable(zone))
+                                        zone->all_unreclaimable = 1;
+                        }
+
                         /*
                          * If we've done a decent amount of scanning and
                          * the reclaim ratio is low, start doing writepage
@@ -2531,6 +2531,12 @@ loop_again:
                             total_scanned > sc.nr_reclaimed + sc.nr_reclaimed / 2)
                                 sc.may_writepage = 1;
 
+                        if (zone->all_unreclaimable) {
+                                if (end_zone && end_zone == i)
+                                        end_zone--;
+                                continue;
+                        }
+
                         if (!zone_watermark_ok_safe(zone, order,
                                         high_wmark_pages(zone), end_zone, 0)) {
                                 all_zones_ok = 0;
@@ -2709,8 +2715,8 @@ static void kswapd_try_to_sleep(pg_data_t *pgdat, int order, int classzone_idx)
  */
 static int kswapd(void *p)
 {
-        unsigned long order;
-        int classzone_idx;
+        unsigned long order, new_order;
+        int classzone_idx, new_classzone_idx;
         pg_data_t *pgdat = (pg_data_t*)p;
         struct task_struct *tsk = current;
 
@@ -2740,17 +2746,23 @@ static int kswapd(void *p)
         tsk->flags |= PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD;
         set_freezable();
 
-        order = 0;
-        classzone_idx = MAX_NR_ZONES - 1;
+        order = new_order = 0;
+        classzone_idx = new_classzone_idx = pgdat->nr_zones - 1;
         for ( ; ; ) {
-                unsigned long new_order;
-                int new_classzone_idx;
                 int ret;
 
-                new_order = pgdat->kswapd_max_order;
-                new_classzone_idx = pgdat->classzone_idx;
-                pgdat->kswapd_max_order = 0;
-                pgdat->classzone_idx = MAX_NR_ZONES - 1;
+                /*
+                 * If the last balance_pgdat was unsuccessful it's unlikely a
+                 * new request of a similar or harder type will succeed soon
+                 * so consider going to sleep on the basis we reclaimed at
+                 */
+                if (classzone_idx >= new_classzone_idx && order == new_order) {
+                        new_order = pgdat->kswapd_max_order;
+                        new_classzone_idx = pgdat->classzone_idx;
+                        pgdat->kswapd_max_order =  0;
+                        pgdat->classzone_idx = pgdat->nr_zones - 1;
+                }
+
                 if (order < new_order || classzone_idx > new_classzone_idx) {
                         /*
                          * Don't sleep if someone wants a larger 'order'
@@ -2763,7 +2775,7 @@ static int kswapd(void *p)
                         order = pgdat->kswapd_max_order;
                         classzone_idx = pgdat->classzone_idx;
                         pgdat->kswapd_max_order = 0;
-                        pgdat->classzone_idx = MAX_NR_ZONES - 1;
+                        pgdat->classzone_idx = pgdat->nr_zones - 1;
                 }
 
                 ret = try_to_freeze();