[PATCH] mm: PageLRU no testset

PG_lru is protected by zone->lru_lock. It does not need TestSet/TestClear
operations.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 11 insertions, 9 deletions

diff --git a/mm/vmscan.c b/mm/vmscan.c
index acb7611cd525..40fb37828e8c 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1042,9 +1042,10 @@ int isolate_lru_page(struct page *page)
         if (PageLRU(page)) {
                 struct zone *zone = page_zone(page);
                 spin_lock_irq(&zone->lru_lock);
-                if (TestClearPageLRU(page)) {
+                if (PageLRU(page)) {
                         ret = 1;
                         get_page(page);
+                        ClearPageLRU(page);
                         if (PageActive(page))
                                 del_page_from_active_list(zone, page);
                         else
@@ -1085,6 +1086,8 @@ static int isolate_lru_pages(int nr_to_scan, struct list_head *src,
                 page = lru_to_page(src);
                 prefetchw_prev_lru_page(page, src, flags);
 
+                BUG_ON(!PageLRU(page));
+
                 list_del(&page->lru);
                 if (unlikely(get_page_testone(page))) {
                         /*
@@ -1100,8 +1103,7 @@ static int isolate_lru_pages(int nr_to_scan, struct list_head *src,
                  * the page is not being freed elsewhere -- the page release
                  * code relies on it.
                  */
-                if (!TestClearPageLRU(page))
-                        BUG();
+                ClearPageLRU(page);
                 list_add(&page->lru, dst);
                 nr_taken++;
         }
@@ -1156,8 +1158,8 @@ static void shrink_cache(struct zone *zone, struct scan_control *sc)
                  */
                 while (!list_empty(&page_list)) {
                         page = lru_to_page(&page_list);
-                        if (TestSetPageLRU(page))
-                                BUG();
+                        BUG_ON(PageLRU(page));
+                        SetPageLRU(page);
                         list_del(&page->lru);
                         if (PageActive(page))
                                 add_page_to_active_list(zone, page);
@@ -1276,8 +1278,8 @@ refill_inactive_zone(struct zone *zone, struct scan_control *sc)
         while (!list_empty(&l_inactive)) {
                 page = lru_to_page(&l_inactive);
                 prefetchw_prev_lru_page(page, &l_inactive, flags);
-                if (TestSetPageLRU(page))
-                        BUG();
+                BUG_ON(PageLRU(page));
+                SetPageLRU(page);
                 if (!TestClearPageActive(page))
                         BUG();
                 list_move(&page->lru, &zone->inactive_list);
@@ -1305,8 +1307,8 @@ refill_inactive_zone(struct zone *zone, struct scan_control *sc)
         while (!list_empty(&l_active)) {
                 page = lru_to_page(&l_active);
                 prefetchw_prev_lru_page(page, &l_active, flags);
-                if (TestSetPageLRU(page))
-                        BUG();
+                BUG_ON(PageLRU(page));
+                SetPageLRU(page);
                 BUG_ON(!PageActive(page));
                 list_move(&page->lru, &zone->active_list);
                 pgmoved++;