From: Christoph Lameter <clameter@sgi.com>
Date: Sun, 8 Jan 2006 09:00:54 +0000 (-0800)
Subject: [PATCH] SwapMig: Drop unused pages immediately
X-Git-Tag: v2.6.16-rc1~887
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=ee27497df36823f2793212cad0997c044eb0e1eb;p=linux-2.6

[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 5393b093a8..73ba4046ed 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