[PATCH v2 1/3] use get_page_migratetype instead of page_private

[Minchan Kim <minchan@kernel.org>]

page allocator uses set_page_private and page_private for handling
migratetype when it frees page. Let's replace them with [set|get]
_freepage_migratetype to make it more clear.

* from v1
  * Change set_page_migratetype with set_freepage_migratetype
  * Add comment on set_freepage_migratetype

Signed-off-by: Minchan Kim <minchan@kernel.org>
---
 include/linux/mm.h  |   12 ++++++++++++
 mm/page_alloc.c     |   10 ++++++----
 mm/page_isolation.c |    2 +-
 3 files changed, 19 insertions(+), 5 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 0514fe9..84d1663f 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -237,6 +237,18 @@ struct inode;
 #define page_private(page)		((page)->private)
 #define set_page_private(page, v)	((page)->private = (v))
 
+/* It's valid only if the page is free path or free_list */
+static inline void set_freepage_migratetype(struct page *page, int migratetype)
+{
+	set_page_private(page, migratetype);
+}
+
+/* It's valid only if the page is free path or free_list */
+static inline int get_freepage_migratetype(struct page *page)
+{
+	return page_private(page);
+}
+
 /*
  * FIXME: take this include out, include page-flags.h in
  * files which need it (119 of them)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index ba3100a..f5ba236 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -671,8 +671,10 @@ static void free_pcppages_bulk(struct zone *zone, int count,
 			/* must delete as __free_one_page list manipulates */
 			list_del(&page->lru);
 			/* MIGRATE_MOVABLE list may include MIGRATE_RESERVEs */
-			__free_one_page(page, zone, 0, page_private(page));
-			trace_mm_page_pcpu_drain(page, 0, page_private(page));
+			__free_one_page(page, zone, 0,
+				get_freepage_migratetype(page));
+			trace_mm_page_pcpu_drain(page, 0,
+				get_freepage_migratetype(page));
 		} while (--to_free && --batch_free && !list_empty(list));
 	}
 	__mod_zone_page_state(zone, NR_FREE_PAGES, count);
@@ -1134,7 +1136,7 @@ static int rmqueue_bulk(struct zone *zone, unsigned int order,
 			if (!is_migrate_cma(mt) && mt != MIGRATE_ISOLATE)
 				mt = migratetype;
 		}
-		set_page_private(page, mt);
+		set_freepage_migratetype(page, mt);
 		list = &page->lru;
 	}
 	__mod_zone_page_state(zone, NR_FREE_PAGES, -(i << order));
@@ -1301,7 +1303,7 @@ void free_hot_cold_page(struct page *page, int cold)
 		return;
 
 	migratetype = get_pageblock_migratetype(page);
-	set_page_private(page, migratetype);
+	set_freepage_migratetype(page, migratetype);
 	local_irq_save(flags);
 	if (unlikely(wasMlocked))
 		free_page_mlock(page);
diff --git a/mm/page_isolation.c b/mm/page_isolation.c
index 247d1f1..87a7929 100644
--- a/mm/page_isolation.c
+++ b/mm/page_isolation.c
@@ -196,7 +196,7 @@ __test_page_isolated_in_pageblock(unsigned long pfn, unsigned long end_pfn)
 		if (PageBuddy(page))
 			pfn += 1 << page_order(page);
 		else if (page_count(page) == 0 &&
-				page_private(page) == MIGRATE_ISOLATE)
+			get_freepage_migratetype(page) == MIGRATE_ISOLATE)
 			pfn += 1;
 		else
 			break;
-- 
1.7.9.5