[PATCH] mm: PageLRU can be non-atomic bit operation

[Hisashi Hifumi]

Hi

PageLRU flag operation is protected by zone->lru_lock, so SetPageLRU/ClearPageLRU
can be replaced to __SetPageLRU/__ClearPageLRU non-atomic bit operation.

Thanks.

Signed-off-by :Hisashi Hifumi <hifumi.hisashi@xxxxxxxxxxxxx>

diff -Nrup linux-2.6.21-rc7.org/include/linux/page-flags.h 
linux-2.6.21-rc7/include/linux/page-flags.h
--- linux-2.6.21-rc7.org/include/linux/page-flags.h	2007-04-17 
16:36:05.000000000 +0900
+++ linux-2.6.21-rc7/include/linux/page-flags.h	2007-04-23 
18:28:19.000000000 +0900
@@ -148,8 +148,7 @@ static inline void SetPageUptodate(struc
 #define TestClearPageDirty(page) test_and_clear_bit(PG_dirty, &(page)->flags)

 #define PageLRU(page)		test_bit(PG_lru, &(page)->flags)
-#define SetPageLRU(page)	set_bit(PG_lru, &(page)->flags)
-#define ClearPageLRU(page)	clear_bit(PG_lru, &(page)->flags)
+#define __SetPageLRU(page)	__set_bit(PG_lru, &(page)->flags)
 #define __ClearPageLRU(page)	__clear_bit(PG_lru, &(page)->flags)

 #define PageActive(page)	test_bit(PG_active, &(page)->flags)
diff -Nrup linux-2.6.21-rc7.org/mm/migrate.c linux-2.6.21-rc7/mm/migrate.c
--- linux-2.6.21-rc7.org/mm/migrate.c	2007-04-17 16:36:05.000000000 +0900
+++ linux-2.6.21-rc7/mm/migrate.c	2007-04-23 18:30:43.000000000 +0900
@@ -52,7 +52,7 @@ int isolate_lru_page(struct page *page,
 		if (PageLRU(page)) {
 			ret = 0;
 			get_page(page);
-			ClearPageLRU(page);
+			__ClearPageLRU(page);
 			if (PageActive(page))
 				del_page_from_active_list(zone, page);
 			else
diff -Nrup linux-2.6.21-rc7.org/mm/swap.c linux-2.6.21-rc7/mm/swap.c
--- linux-2.6.21-rc7.org/mm/swap.c	2007-02-05 03:44:54.000000000 +0900
+++ linux-2.6.21-rc7/mm/swap.c	2007-04-23 18:29:51.000000000 +0900
@@ -364,7 +364,7 @@ void __pagevec_lru_add(struct pagevec *p
 			spin_lock_irq(&zone->lru_lock);
 		}
 		VM_BUG_ON(PageLRU(page));
-		SetPageLRU(page);
+		__SetPageLRU(page);
 		add_page_to_inactive_list(zone, page);
 	}
 	if (zone)
@@ -391,7 +391,7 @@ void __pagevec_lru_add_active(struct pag
 			spin_lock_irq(&zone->lru_lock);
 		}
 		VM_BUG_ON(PageLRU(page));
-		SetPageLRU(page);
+		__SetPageLRU(page);
 		VM_BUG_ON(PageActive(page));
 		SetPageActive(page);
 		add_page_to_active_list(zone, page);
diff -Nrup linux-2.6.21-rc7.org/mm/vmscan.c linux-2.6.21-rc7/mm/vmscan.c
--- linux-2.6.21-rc7.org/mm/vmscan.c	2007-04-17 16:36:05.000000000 +0900
+++ linux-2.6.21-rc7/mm/vmscan.c	2007-04-23 18:30:30.000000000 +0900
@@ -642,7 +642,7 @@ static unsigned long isolate_lru_pages(u
 			 * sure the page is not being freed elsewhere -- the
 			 * page release code relies on it.
 			 */
-			ClearPageLRU(page);
+			__ClearPageLRU(page);
 			target = dst;
 			nr_taken++;
 		} /* else it is being freed elsewhere */
@@ -704,7 +704,7 @@ static unsigned long shrink_inactive_lis
 		while (!list_empty(&page_list)) {
 			page = lru_to_page(&page_list);
 			VM_BUG_ON(PageLRU(page));
-			SetPageLRU(page);
+			__SetPageLRU(page);
 			list_del(&page->lru);
 			if (PageActive(page))
 				add_page_to_active_list(zone, page);
@@ -851,7 +851,7 @@ force_reclaim_mapped:
 		page = lru_to_page(&l_inactive);
 		prefetchw_prev_lru_page(page, &l_inactive, flags);
 		VM_BUG_ON(PageLRU(page));
-		SetPageLRU(page);
+		__SetPageLRU(page);
 		VM_BUG_ON(!PageActive(page));
 		ClearPageActive(page);

@@ -881,7 +881,7 @@ force_reclaim_mapped:
 		page = lru_to_page(&l_active);
 		prefetchw_prev_lru_page(page, &l_active, flags);
 		VM_BUG_ON(PageLRU(page));
-		SetPageLRU(page);
+		__SetPageLRU(page);
 		VM_BUG_ON(!PageActive(page));
 		list_move(&page->lru, &zone->active_list);
 		pgmoved++; 

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