RSS container, fix freeing of active pages

Hi, Pavel,

I missed you on the list and the patch did not make it to lkml. I am resending the patch.

------------------------------------------------------------------------

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 <[email protected]>

---

 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

mm/rss_container.c renamed from mm/rss_container.c~rss-fix-free-of-active-pages +3 -2

@@ -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);
 

mm/rss_container.c renamed from mm/rss_container.c~rss-fix-free-of-active-pages +12 -6

+		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 _

Hm... Did you see such a situation in your experiments?

If yes, then why not fix it in a normal way by moving the pages from list to list where appropriate?