3 files changed, 23 insertions, 0 deletions

diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h
index a5bb15018b5c..92a86b2cce33 100644
--- a/include/linux/vmstat.h
+++ b/include/linux/vmstat.h
@@ -198,6 +198,8 @@ extern void __dec_zone_state(struct zone *, enum zone_stat_item);
 void refresh_cpu_vm_stats(int);
 void refresh_zone_stat_thresholds(void);
 
+void drain_zonestat(struct zone *zone, struct per_cpu_pageset *);
+
 int calculate_pressure_threshold(struct zone *zone);
 int calculate_normal_threshold(struct zone *zone);
 void set_pgdat_percpu_threshold(pg_data_t *pgdat,
@@ -251,6 +253,8 @@ static inline void __dec_zone_page_state(struct page *page,
 static inline void refresh_cpu_vm_stats(int cpu) { }
 static inline void refresh_zone_stat_thresholds(void) { }
 
+static inline void drain_zonestat(struct zone *zone,
+                        struct per_cpu_pageset *pset) { }
 #endif          /* CONFIG_SMP */
 
 static inline void __mod_zone_freepage_state(struct zone *zone, int nr_pages,
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 9b8e6243a524..5485f0ef4ec3 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -5916,6 +5916,7 @@ static int __meminit __zone_pcp_update(void *data)
                 local_irq_save(flags);
                 if (pcp->count > 0)
                         free_pcppages_bulk(zone, pcp->count, pcp);
+                drain_zonestat(zone, pset);
                 setup_pageset(pset, batch);
                 local_irq_restore(flags);
         }
@@ -5932,10 +5933,16 @@ void __meminit zone_pcp_update(struct zone *zone)
 void zone_pcp_reset(struct zone *zone)
 {
         unsigned long flags;
+        int cpu;
+        struct per_cpu_pageset *pset;
 
         /* avoid races with drain_pages()  */
         local_irq_save(flags);
         if (zone->pageset != &boot_pageset) {
+                for_each_online_cpu(cpu) {
+                        pset = per_cpu_ptr(zone->pageset, cpu);
+                        drain_zonestat(zone, pset);
+                }
                 free_percpu(zone->pageset);
                 zone->pageset = &boot_pageset;
         }
diff --git a/mm/vmstat.c b/mm/vmstat.c
index 05e3a9913744..2f11309955cc 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -495,6 +495,18 @@ void refresh_cpu_vm_stats(int cpu)
                         atomic_long_add(global_diff[i], &vm_stat[i]);
 }
 
+void drain_zonestat(struct zone *zone, struct per_cpu_pageset *pset)
+{
+        int i;
+
+        for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
+                if (pset->vm_stat_diff[i]) {
+                        int v = pset->vm_stat_diff[i];
+                        pset->vm_stat_diff[i] = 0;
+                        atomic_long_add(v, &zone->vm_stat[i]);
+                        atomic_long_add(v, &vm_stat[i]);
+                }
+}
 #endif
 
 #ifdef CONFIG_NUMA