[PATCH] Use ZVC for free_pages

This is again simplifies some of the VM counter calculations through the use
of the ZVC consolidated counters.

[michal.k.k.piotrowski@gmail.com: build fix]
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Michal Piotrowski <michal.k.k.piotrowski@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

6 files changed, 25 insertions, 46 deletions

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 9137d1b9735..824279c7884 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -47,6 +47,7 @@ struct zone_padding {
 #endif
 
 enum zone_stat_item {
+        NR_FREE_PAGES,
         NR_INACTIVE,
         NR_ACTIVE,
         NR_ANON_PAGES,  /* Mapped anonymous pages */
@@ -157,7 +158,6 @@ enum zone_type {
 
 struct zone {
         /* Fields commonly accessed by the page allocator */
-        unsigned long           free_pages;
         unsigned long           pages_min, pages_low, pages_high;
         /*
          * We don't know if the memory that we're going to allocate will be freeable
diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c
index c024606221c..fc53ad06812 100644
--- a/kernel/power/snapshot.c
+++ b/kernel/power/snapshot.c
@@ -591,7 +591,7 @@ static unsigned int count_free_highmem_pages(void)
 
         for_each_zone(zone)
                 if (populated_zone(zone) && is_highmem(zone))
-                        cnt += zone->free_pages;
+                        cnt += zone_page_state(zone, NR_FREE_PAGES);
 
         return cnt;
 }
@@ -869,7 +869,7 @@ static int enough_free_mem(unsigned int nr_pages, unsigned int nr_highmem)
         for_each_zone(zone) {
                 meta += snapshot_additional_pages(zone);
                 if (!is_highmem(zone))
-                        free += zone->free_pages;
+                        free += zone_page_state(zone, NR_FREE_PAGES);
         }
 
         nr_pages += count_pages_for_highmem(nr_highmem);
diff --git a/kernel/power/swsusp.c b/kernel/power/swsusp.c
index 31aa0390c77..7fb834397a0 100644
--- a/kernel/power/swsusp.c
+++ b/kernel/power/swsusp.c
@@ -230,9 +230,10 @@ int swsusp_shrink_memory(void)
                 for_each_zone (zone)
                         if (populated_zone(zone)) {
                                 if (is_highmem(zone)) {
-                                        highmem_size -= zone->free_pages;
+                                        highmem_size -=
+                                        zone_page_state(zone, NR_FREE_PAGES);
                                 } else {
-                                        tmp -= zone->free_pages;
+                                        tmp -= zone_page_state(zone, NR_FREE_PAGES);
                                         tmp += zone->lowmem_reserve[ZONE_NORMAL];
                                         tmp += snapshot_additional_pages(zone);
                                 }
diff --git a/mm/highmem.c b/mm/highmem.c
index 0206e7e5018..51e1c1995fe 100644
--- a/mm/highmem.c
+++ b/mm/highmem.c
@@ -47,7 +47,8 @@ unsigned int nr_free_highpages (void)
         unsigned int pages = 0;
 
         for_each_online_pgdat(pgdat)
-                pages += pgdat->node_zones[ZONE_HIGHMEM].free_pages;
+                pages += zone_page_state(&pgdat->node_zones[ZONE_HIGHMEM],
+                        NR_FREE_PAGES);
 
         return pages;
 }
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 07c954e5327..ba62d8789f7 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -395,7 +395,7 @@ static inline void __free_one_page(struct page *page,
         VM_BUG_ON(page_idx & (order_size - 1));
         VM_BUG_ON(bad_range(zone, page));
 
-        zone->free_pages += order_size;
+        __mod_zone_page_state(zone, NR_FREE_PAGES, order_size);
         while (order < MAX_ORDER-1) {
                 unsigned long combined_idx;
                 struct free_area *area;
@@ -631,7 +631,7 @@ static struct page *__rmqueue(struct zone *zone, unsigned int order)
                 list_del(&page->lru);
                 rmv_page_order(page);
                 area->nr_free--;
-                zone->free_pages -= 1UL << order;
+                __mod_zone_page_state(zone, NR_FREE_PAGES, - (1UL << order));
                 expand(zone, page, order, current_order, area);
                 return page;
         }
@@ -989,7 +989,8 @@ int zone_watermark_ok(struct zone *z, int order, unsigned long mark,
                       int classzone_idx, int alloc_flags)
 {
         /* free_pages my go negative - that's OK */
-        long min = mark, free_pages = z->free_pages - (1 << order) + 1;
+        long min = mark;
+        long free_pages = zone_page_state(z, NR_FREE_PAGES) - (1 << order) + 1;
         int o;
 
         if (alloc_flags & ALLOC_HIGH)
@@ -1444,13 +1445,7 @@ EXPORT_SYMBOL(free_pages);
  */
 unsigned int nr_free_pages(void)
 {
-        unsigned int sum = 0;
-        struct zone *zone;
-
-        for_each_zone(zone)
-                sum += zone->free_pages;
-
-        return sum;
+        return global_page_state(NR_FREE_PAGES);
 }
 
 EXPORT_SYMBOL(nr_free_pages);
@@ -1458,13 +1453,7 @@ EXPORT_SYMBOL(nr_free_pages);
 #ifdef CONFIG_NUMA
 unsigned int nr_free_pages_pgdat(pg_data_t *pgdat)
 {
-        unsigned int sum = 0;
-        enum zone_type i;
-
-        for (i = 0; i < MAX_NR_ZONES; i++)
-                sum += pgdat->node_zones[i].free_pages;
-
-        return sum;
+        return node_page_state(pgdat->node_id, NR_FREE_PAGES);
 }
 #endif
 
@@ -1514,7 +1503,7 @@ void si_meminfo(struct sysinfo *val)
 {
         val->totalram = totalram_pages;
         val->sharedram = 0;
-        val->freeram = nr_free_pages();
+        val->freeram = global_page_state(NR_FREE_PAGES);
         val->bufferram = nr_blockdev_pages();
         val->totalhigh = totalhigh_pages;
         val->freehigh = nr_free_highpages();
@@ -1529,10 +1518,11 @@ void si_meminfo_node(struct sysinfo *val, int nid)
         pg_data_t *pgdat = NODE_DATA(nid);
 
         val->totalram = pgdat->node_present_pages;
-        val->freeram = nr_free_pages_pgdat(pgdat);
+        val->freeram = node_page_state(nid, NR_FREE_PAGES);
 #ifdef CONFIG_HIGHMEM
         val->totalhigh = pgdat->node_zones[ZONE_HIGHMEM].present_pages;
-        val->freehigh = pgdat->node_zones[ZONE_HIGHMEM].free_pages;
+        val->freehigh = zone_page_state(&pgdat->node_zones[ZONE_HIGHMEM],
+                        NR_FREE_PAGES);
 #else
         val->totalhigh = 0;
         val->freehigh = 0;
@@ -1580,13 +1570,13 @@ void show_free_areas(void)
         get_zone_counts(&active, &inactive, &free);
 
         printk("Active:%lu inactive:%lu dirty:%lu writeback:%lu unstable:%lu\n"
-                " free:%u slab:%lu mapped:%lu pagetables:%lu bounce:%lu\n",
+                " free:%lu slab:%lu mapped:%lu pagetables:%lu bounce:%lu\n",
                 active,
                 inactive,
                 global_page_state(NR_FILE_DIRTY),
                 global_page_state(NR_WRITEBACK),
                 global_page_state(NR_UNSTABLE_NFS),
-                nr_free_pages(),
+                global_page_state(NR_FREE_PAGES),
                 global_page_state(NR_SLAB_RECLAIMABLE) +
                         global_page_state(NR_SLAB_UNRECLAIMABLE),
                 global_page_state(NR_FILE_MAPPED),
@@ -1612,7 +1602,7 @@ void show_free_areas(void)
                         " all_unreclaimable? %s"
                         "\n",
                         zone->name,
-                        K(zone->free_pages),
+                        K(zone_page_state(zone, NR_FREE_PAGES)),
                         K(zone->pages_min),
                         K(zone->pages_low),
                         K(zone->pages_high),
@@ -2675,7 +2665,6 @@ static void __meminit free_area_init_core(struct pglist_data *pgdat,
                 spin_lock_init(&zone->lru_lock);
                 zone_seqlock_init(zone);
                 zone->zone_pgdat = pgdat;
-                zone->free_pages = 0;
 
                 zone->prev_priority = DEF_PRIORITY;
 
diff --git a/mm/vmstat.c b/mm/vmstat.c
index 5462106725d..2386716f175 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -16,30 +16,17 @@
 void __get_zone_counts(unsigned long *active, unsigned long *inactive,
                         unsigned long *free, struct pglist_data *pgdat)
 {
-        struct zone *zones = pgdat->node_zones;
-        int i;
-
         *active = node_page_state(pgdat->node_id, NR_ACTIVE);
         *inactive = node_page_state(pgdat->node_id, NR_INACTIVE);
-        *free = 0;
-        for (i = 0; i < MAX_NR_ZONES; i++) {
-                *free += zones[i].free_pages;
-        }
+        *free = node_page_state(pgdat->node_id, NR_FREE_PAGES);
 }
 
 void get_zone_counts(unsigned long *active,
                 unsigned long *inactive, unsigned long *free)
 {
-        struct pglist_data *pgdat;
-
         *active = global_page_state(NR_ACTIVE);
         *inactive = global_page_state(NR_INACTIVE);
-        *free = 0;
-        for_each_online_pgdat(pgdat) {
-                unsigned long l, m, n;
-                __get_zone_counts(&l, &m, &n, pgdat);
-                *free += n;
-        }
+        *free = global_page_state(NR_FREE_PAGES);
 }
 
 #ifdef CONFIG_VM_EVENT_COUNTERS
@@ -454,6 +441,7 @@ const struct seq_operations fragmentation_op = {
 
 static const char * const vmstat_text[] = {
         /* Zoned VM counters */
+        "nr_free_pages",
         "nr_active",
         "nr_inactive",
         "nr_anon_pages",
@@ -534,7 +522,7 @@ static int zoneinfo_show(struct seq_file *m, void *arg)
                            "\n        scanned  %lu (a: %lu i: %lu)"
                            "\n        spanned  %lu"
                            "\n        present  %lu",
-                           zone->free_pages,
+                           zone_page_state(zone, NR_FREE_PAGES),
                            zone->pages_min,
                            zone->pages_low,
                            zone->pages_high,