On Mon, Dec 12, 2011 at 03:35:03PM +0100, Michal Nazarewicz wrote:

quoted

On Fri, Nov 18, 2011 at 05:43:10PM +0100, Marek Szyprowski wrote:

quoted

From: Michal Nazarewicz <redacted>

diff --git a/mm/compaction.c b/mm/compaction.c
index 6afae0e..09c9702 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c

@@ -111,7 +111,10 @@ skip:

next:
		pfn += isolated;
-		page += isolated;
+		if (zone_pfn_same_memmap(pfn - isolated, pfn))
+			page += isolated;
+		else
+			page = pfn_to_page(pfn);
	}

On Mon, 12 Dec 2011 15:19:53 +0100, Mel Gorman [off-list ref] wrote:

quoted

Is this necessary?

We are isolating pages, the largest of which is a MAX_ORDER_NR_PAGES
page.  [...]

This is not true for CMA.

To be clear, I'm referring to a single page being isolated here. It may
or may not be a high-order page but it's still going to be less then
MAX_ORDER_NR_PAGES so you should be able check when a new block is
entered and pfn_to_page is necessary.

-- 
Mel Gorman
SUSE Labs