[Devel] [RSS Controller -v2] Fix freeing of active pages

[Balbir Singh]

This patch fixes the bad_page() warning seen while freeing a container page.
By default all container pages are added to the active list on the
container. This patch lazily moves pages to the right list, so that a page
on the active list of the zone LRU and the inactive list of the container
does not get freed. If that happens, we see a warning from bad_page().

Signed-off-by: Balbir Singh <balbir at linux.vnet.ibm.com>
---

 linux/rss_container.h |    0 
 mm/rss_container.c    |   30 ++++++++++++++++++++++--------
 2 files changed, 22 insertions(+), 8 deletions(-)

diff -puN mm/rss_container.c~rss-fix-free-of-active-pages mm/rss_container.c
--- linux-2.6.20/mm/rss_container.c~rss-fix-free-of-active-pages	2007-04-25 22:05:54.000000000 +0530
+++ linux-2.6.20-balbir/mm/rss_container.c	2007-04-25 23:12:35.000000000 +0530
@@ -119,18 +119,36 @@ void container_rss_move_lists(struct pag
 }
 
 static unsigned long isolate_container_pages(unsigned long nr_to_scan,
-		struct list_head *src, struct list_head *dst,
-		unsigned long *scanned, struct zone *zone)
+		struct rss_container *rss, struct list_head *dst,
+		unsigned long *scanned, struct zone *zone, bool active)
 {
 	unsigned long nr_taken = 0;
 	struct page *page;
 	struct page_container *pc;
 	unsigned long scan;
+	struct list_head *src;
 	LIST_HEAD(pc_list);
 
+	src = active ? &rss->active_list : &rss->inactive_list;
+
 	for (scan = 0; scan < nr_to_scan && !list_empty(src); scan++) {
 		pc = list_entry(src->prev, struct page_container, list);
 		page = pc->page;
+
+		/*
+		 * We might have got our active, inactive lists
+		 * incorrect, fix it here
+		 */
+		if (active && !PageActive(page)) {
+			list_move(&pc->list, &rss->inactive_list);
+			scan--;
+			continue;
+		} else if (!active && PageActive(page)) {
+			list_move(&pc->list, &rss->active_list);
+			scan--;
+			continue;
+		}
+
 		if (page_zone(page) != zone)
 			continue;
 
@@ -158,12 +176,8 @@ unsigned long isolate_pages_in_container
 	unsigned long ret;
 
 	spin_lock(&rss->res.lock);
-	if (active)
-		ret = isolate_container_pages(nr_to_scan, &rss->active_list,
-				dst, scanned, zone);
-	else
-		ret = isolate_container_pages(nr_to_scan, &rss->inactive_list,
-				dst, scanned, zone);
+	ret = isolate_container_pages(nr_to_scan, rss, dst, scanned, zone,
+					active);
 	spin_unlock(&rss->res.lock);
 	return ret;
 }
diff -puN include/linux/rss_container.h~rss-fix-free-of-active-pages include/linux/rss_container.h
_

-- 
	Warm Regards,
	Balbir Singh
	Linux Technology Center
	IBM, ISTL