Do not check references to a page during zone reclaim

Shrink_list and refill_inactive() check all ptes pointing to a page
for reference bits in order to decide if the page should be put on
the active list. This is not necessary for zone_reclaim since we
are only interested in removing unmapped pages. Skip the checks in both
functions.

Signed-off-by: Christoph Lameter <clameter@sgi.com>

Index: linux-2.6.16-rc2/mm/vmscan.c
===================================================================
--- linux-2.6.16-rc2.orig/mm/vmscan.c	2006-02-02 22:03:08.000000000 -0800
+++ linux-2.6.16-rc2/mm/vmscan.c	2006-02-11 13:29:51.000000000 -0800
@@ -443,6 +443,10 @@ static int shrink_list(struct list_head 
 		BUG_ON(PageActive(page));
 
 		sc->nr_scanned++;
+
+		if (!sc->may_swap && page_mapped(page))
+			goto keep_locked;
+
 		/* Double the slab pressure for mapped and swapcache pages */
 		if (page_mapped(page) || PageSwapCache(page))
 			sc->nr_scanned++;
@@ -1216,7 +1220,7 @@ refill_inactive_zone(struct zone *zone, 
 	 * Now use this metric to decide whether to start moving mapped memory
 	 * onto the inactive list.
 	 */
-	if (swap_tendency >= 100)
+	if (swap_tendency >= 100 && sc->may_swap)
 		reclaim_mapped = 1;
 
 	while (!list_empty(&l_hold)) {