mm, mem-hotplug: update pcp->stat_threshold when memory hotplug occur

Currently, cpu hotplug updates pcp->stat_threshold, but memory hotplug
doesn't.  There is no reason for this.

[akpm@linux-foundation.org: fix CONFIG_SMP=n build]
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 3 insertions, 0 deletions

diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h
index e73d1030f2f7..51359837511a 100644
--- a/include/linux/vmstat.h
+++ b/include/linux/vmstat.h
@@ -261,6 +261,7 @@ extern void dec_zone_state(struct zone *, enum zone_stat_item);
 extern void __dec_zone_state(struct zone *, enum zone_stat_item);
 
 void refresh_cpu_vm_stats(int);
+void refresh_zone_stat_thresholds(void);
 
 int calculate_pressure_threshold(struct zone *zone);
 int calculate_normal_threshold(struct zone *zone);
@@ -313,6 +314,8 @@ static inline void __dec_zone_page_state(struct page *page,
 #define set_pgdat_percpu_threshold(pgdat, callback) { }
 
 static inline void refresh_cpu_vm_stats(int cpu) { }
+static inline void refresh_zone_stat_thresholds(void) { }
+
 #endif          /* CONFIG_SMP */
 
 extern const char * const vmstat_text[];