2 files changed, 40 insertions, 0 deletions

diff --git a/include/linux/swap.h b/include/linux/swap.h
index 54eac8a39a4c..5b1fdf1cff4f 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -155,6 +155,7 @@ extern void swapin_readahead(swp_entry_t, unsigned long, struct vm_area_struct *
 /* linux/mm/page_alloc.c */
 extern unsigned long totalram_pages;
 extern unsigned long totalhigh_pages;
+extern unsigned long totalreserve_pages;
 extern long nr_swap_pages;
 extern unsigned int nr_free_pages(void);
 extern unsigned int nr_free_pages_pgdat(pg_data_t *pgdat);
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index b8165e037dee..97d6827c7d66 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -51,6 +51,7 @@ nodemask_t node_possible_map __read_mostly = NODE_MASK_ALL;
 EXPORT_SYMBOL(node_possible_map);
 unsigned long totalram_pages __read_mostly;
 unsigned long totalhigh_pages __read_mostly;
+unsigned long totalreserve_pages __read_mostly;
 long nr_swap_pages;
 int percpu_pagelist_fraction;
 
@@ -2477,6 +2478,38 @@ void __init page_alloc_init(void)
 }
 
 /*
+ * calculate_totalreserve_pages - called when sysctl_lower_zone_reserve_ratio
+ *      or min_free_kbytes changes.
+ */
+static void calculate_totalreserve_pages(void)
+{
+        struct pglist_data *pgdat;
+        unsigned long reserve_pages = 0;
+        int i, j;
+
+        for_each_online_pgdat(pgdat) {
+                for (i = 0; i < MAX_NR_ZONES; i++) {
+                        struct zone *zone = pgdat->node_zones + i;
+                        unsigned long max = 0;
+
+                        /* Find valid and maximum lowmem_reserve in the zone */
+                        for (j = i; j < MAX_NR_ZONES; j++) {
+                                if (zone->lowmem_reserve[j] > max)
+                                        max = zone->lowmem_reserve[j];
+                        }
+
+                        /* we treat pages_high as reserved pages. */
+                        max += zone->pages_high;
+
+                        if (max > zone->present_pages)
+                                max = zone->present_pages;
+                        reserve_pages += max;
+                }
+        }
+        totalreserve_pages = reserve_pages;
+}
+
+/*
  * setup_per_zone_lowmem_reserve - called whenever
  *      sysctl_lower_zone_reserve_ratio changes.  Ensures that each zone
  *      has a correct pages reserved value, so an adequate number of
@@ -2507,6 +2540,9 @@ static void setup_per_zone_lowmem_reserve(void)
                         }
                 }
         }
+
+        /* update totalreserve_pages */
+        calculate_totalreserve_pages();
 }
 
 /*
@@ -2561,6 +2597,9 @@ void setup_per_zone_pages_min(void)
                 zone->pages_high  = zone->pages_min + tmp / 2;
                 spin_unlock_irqrestore(&zone->lru_lock, flags);
         }
+
+        /* update totalreserve_pages */
+        calculate_totalreserve_pages();
 }
 
 /*