[PATCH] zone reclaim: 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>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 5 insertions, 1 deletions

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 5db32fdfaf39..e1c64230ffdd 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -443,6 +443,10 @@ static int shrink_list(struct list_head *page_list, struct scan_control *sc)
                 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++;
@@ -1231,7 +1235,7 @@ refill_inactive_zone(struct zone *zone, struct scan_control *sc)
          * 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)) {