cma: fix counting of isolated pages

Isolated free pages shouldn't be accounted to NR_FREE_PAGES counter.  Fix
it by properly decreasing/increasing NR_FREE_PAGES counter in
set_migratetype_isolate()/unset_migratetype_isolate() and removing counter
adjustment for isolated pages from free_one_page() and split_free_page().

Signed-off-by: Bartlomiej Zolnierkiewicz <[email protected]>
Signed-off-by: Kyungmin Park <[email protected]>
Cc: Marek Szyprowski <[email protected]>
Cc: Michal Nazarewicz <[email protected]>
Cc: Minchan Kim <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Hugh Dickins <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

Author: bzolnier

mm/page_alloc.c

@@ -691,7 +691,8 @@ static void free_one_page(struct zone *zone, struct page *page, int order,
 	zone->pages_scanned = 0;
 
 	__free_one_page(page, zone, order, migratetype);
-	__mod_zone_page_state(zone, NR_FREE_PAGES, 1 << order);
+	if (unlikely(migratetype != MIGRATE_ISOLATE))
+		__mod_zone_page_state(zone, NR_FREE_PAGES, 1 << order);
 	spin_unlock(&zone->lock);
 }
 
@@ -1392,6 +1393,7 @@ int capture_free_page(struct page *page, int alloc_order, int migratetype)
 	unsigned int order;
 	unsigned long watermark;
 	struct zone *zone;
+	int mt;
 
 	BUG_ON(!PageBuddy(page));
 
@@ -1407,7 +1409,10 @@ int capture_free_page(struct page *page, int alloc_order, int migratetype)
 	list_del(&page->lru);
 	zone->free_area[order].nr_free--;
 	rmv_page_order(page);
-	__mod_zone_page_state(zone, NR_FREE_PAGES, -(1UL << order));
+
+	mt = get_pageblock_migratetype(page);
+	if (unlikely(mt != MIGRATE_ISOLATE))
+		__mod_zone_page_state(zone, NR_FREE_PAGES, -(1UL << order));
 
 	if (alloc_order != order)
 		expand(zone, page, alloc_order, order,

mm/page_isolation.c

@@ -76,8 +76,12 @@ int set_migratetype_isolate(struct page *page)
 
 out:
 	if (!ret) {
+		unsigned long nr_pages;
+
 		set_pageblock_isolate(page);
-		move_freepages_block(zone, page, MIGRATE_ISOLATE);
+		nr_pages = move_freepages_block(zone, page, MIGRATE_ISOLATE);
+
+		__mod_zone_page_state(zone, NR_FREE_PAGES, -nr_pages);
 	}
 
 	spin_unlock_irqrestore(&zone->lock, flags);
@@ -89,12 +93,14 @@ int set_migratetype_isolate(struct page *page)
 void unset_migratetype_isolate(struct page *page, unsigned migratetype)
 {
 	struct zone *zone;
-	unsigned long flags;
+	unsigned long flags, nr_pages;
+
 	zone = page_zone(page);
 	spin_lock_irqsave(&zone->lock, flags);
 	if (get_pageblock_migratetype(page) != MIGRATE_ISOLATE)
 		goto out;
-	move_freepages_block(zone, page, migratetype);
+	nr_pages = move_freepages_block(zone, page, migratetype);
+	__mod_zone_page_state(zone, NR_FREE_PAGES, nr_pages);
 	restore_pageblock_isolate(page, migratetype);
 out:
 	spin_unlock_irqrestore(&zone->lock, flags);