buddy allocator without bitmap [2/3]

diff -puN mm/page_alloc.c~eliminate-bitmap-alloc mm/page_alloc.c
@@ -288,9 +288,6 @@ void __free_pages_ok(struct page *page,
 	free_pages_bulk(page_zone(page), 1, &list, order);
 }
 
-#define MARK_USED(index, order, area) \
-	__change_bit((index) >> (1+(order)), (area)->map)
-
 /*
  * The order of subdivision here is critical for the IO subsystem.
  * Please do not alter this order without good reasons and regression

@@ -307,7 +304,7 @@ void __free_pages_ok(struct page *page,
  */
 static inline struct page *
 expand(struct zone *zone, struct page *page,
-	 unsigned long index, int low, int high, struct free_area *area)
+       int low, int high, struct free_area *area)
 {
 	unsigned long size = 1 << high;
 

@@ -317,7 +314,9 @@ expand(struct zone *zone, struct page *p
 		size >>= 1;
 		BUG_ON(bad_range(zone, &page[size]));
 		list_add(&page[size].lru, &area->free_list);
-		MARK_USED(index + size, high, area);
+		/* Note: already have lock, we don't need to use atomic ops */
+		set_page_order(&page[size], high);
+		SetPagePrivate(&page[size]);
 	}
 	return page;
 }

@@ -371,7 +370,6 @@ static struct page *__rmqueue(struct zon
 	struct free_area * area;
 	unsigned int current_order;
 	struct page *page;
-	unsigned int index;
 
 	for (current_order = order; current_order < MAX_ORDER; ++current_order) {
 		area = zone->free_area + current_order;

@@ -380,11 +378,10 @@ static struct page *__rmqueue(struct zon
 
 		page = list_entry(area->free_list.next, struct page, lru);
 		list_del(&page->lru);
-		index = page - zone->zone_mem_map;
-		if (current_order != MAX_ORDER-1)
-			MARK_USED(index, current_order, area);
+		/* Note: already have lock, we don't need to use atomic ops */
+		ClearPagePrivate(page);
 		zone->free_pages -= 1UL << order;
-		return expand(zone, page, index, order, current_order, area);
+		return expand(zone, page, order, current_order, area);
 	}
 
 	return NULL;