On Mon, Dec 12, 2011 at 03:23:02PM +0100, Michal Nazarewicz wrote:

quoted

On Fri, Nov 18, 2011 at 05:43:08PM +0100, Marek Szyprowski wrote:

quoted

From: Michal Nazarewicz <redacted>

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 9dd443d..58d1a2e 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c

@@ -628,6 +628,18 @@ static void free_pcppages_bulk(struct zone *zone, int count,

			page = list_entry(list->prev, struct page, lru);
			/* must delete as __free_one_page list manipulates */
			list_del(&page->lru);
+
+			/*
+			 * When page is isolated in set_migratetype_isolate()
+			 * function it's page_private is not changed since the
+			 * function has no way of knowing if it can touch it.
+			 * This means that when a page is on PCP list, it's
+			 * page_private no longer matches the desired migrate
+			 * type.
+			 */
+			if (get_pageblock_migratetype(page) == MIGRATE_ISOLATE)
+				set_page_private(page, MIGRATE_ISOLATE);
+

On Mon, 12 Dec 2011 14:42:35 +0100, Mel Gorman [off-list ref] wrote:

quoted

How much of a problem is this in practice?

IIRC, this lead to allocation being made from area marked as isolated
or some such.

And I believe that nothing prevents that from happening. I was just
wondering how common it was in practice. Draining the per-cpu lists
should work as a substitute either way.

-- 
Mel Gorman
SUSE Labs