[PATCH] SwapMig: Drop unused pages immediately

Drop unused pages immediately

If a page is encountered that is only referenced by the migration code then
there is no reason to swap or migrate the page.  Release the page by calling
move_to_lru().

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 5393b093a87ba898bb88aec37691bbd795186580..73ba4046ed272eb290cea68dca37d02a5ae64092 100644 (file)
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -689,6 +689,11 @@ redo:
        list_for_each_entry_safe(page, page2, l, lru) {
                cond_resched();
 
+               if (page_count(page) == 1) {
+                       /* page was freed from under us. So we are done. */
+                       move_to_lru(page);
+                       continue;
+               }
                /*
                 * Skip locked pages during the first two passes to give the
                 * functions holding the lock time to release the page. Later we