Avoid unecessary zone spinlocking on refill_inactive_zone()

diff -Nur --exclude='*.cmd' linux-2.6.7/mm/swap.c linux-2.6.7-vmscan/mm/swap.c
@@ -192,6 +192,49 @@
 
 EXPORT_SYMBOL(__page_cache_release);
 
+
+void release_pages_nolock(struct page **pages, int nr, struct zone *zone)
+{
+	int i;
+	struct pagevec pages_to_free;
+	int to_free = 0;
+
+
+	pagevec_init(&pages_to_free, 1);
+	for (i = 0; i < nr; i++) {
+		struct page *page = pages[i];
+
+		if (PageReserved(page) || !put_page_testzero(page))
+			continue;
+
+		if (TestClearPageLRU(page))
+			del_page_from_lru(zone, page);
+
+		if (page_count(page) == 0) {
+			if (!pagevec_add(&pages_to_free, page)) {
+				spin_unlock_irq(&zone->lru_lock);
+				to_free = 0;
+				__pagevec_free(&pages_to_free);
+				pagevec_reinit(&pages_to_free);
+				spin_lock_irq(&zone->lru_lock);
+			}
+			to_free = 1;
+		}
+			
+	}
+
+	if (to_free) {
+		spin_unlock_irq(&zone->lru_lock);
+		pagevec_free(&pages_to_free);
+		spin_lock_irq(&zone->lru_lock);
+	}
+}
+
+void release_pages_nl(struct pagevec *pvec, struct zone *zone) {
+	release_pages_nolock(pvec->pages, pagevec_count(pvec), zone);
+	pagevec_reinit(pvec);
+}
+
 /*
  * Batched page_cache_release().  Decrement the reference count on all the
  * passed pages.  If it fell to zero then remove the page from the LRU and

diff -Nur --exclude='*.cmd' linux-2.6.7/mm/vmscan.c linux-2.6.7-vmscan/mm/vmscan.c
@@ -74,6 +74,8 @@
 	int may_writepage;
 };
 
+void release_pages_nl(struct pagevec *, struct zone *zone);
+
 /*
  * The list of shrinker callbacks used by to apply pressure to
  * ageable caches.

@@ -753,13 +755,14 @@
 		pgmoved++;
 		if (!pagevec_add(&pvec, page)) {
 			zone->nr_inactive += pgmoved;
-			spin_unlock_irq(&zone->lru_lock);
 			pgdeactivate += pgmoved;
 			pgmoved = 0;
-			if (buffer_heads_over_limit)
+			if (buffer_heads_over_limit) {
+				spin_unlock_irq(&zone->lock);
 				pagevec_strip(&pvec);
-			__pagevec_release(&pvec);
-			spin_lock_irq(&zone->lru_lock);
+				spin_lock_irq(&zone->lock);
+			}
+			release_pages_nl(&pvec, zone);
 		}
 	}
 	zone->nr_inactive += pgmoved;

@@ -782,9 +785,7 @@
 		if (!pagevec_add(&pvec, page)) {
 			zone->nr_active += pgmoved;
 			pgmoved = 0;
-			spin_unlock_irq(&zone->lru_lock);
-			__pagevec_release(&pvec);
-			spin_lock_irq(&zone->lru_lock);
+			release_pages_nl(&pvec, zone);
 		}
 	}
 	zone->nr_active += pgmoved;