[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>

1 files changed, 5 insertions, 0 deletions

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 5393b093a87b..73ba4046ed27 100644
--- 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