Re: [Linaro-mm-sig] [PATCH 08/15] mm: mmzone: MIGRATE_CMA migration type added

On Mon, Jan 30, 2012 at 02:06:50PM +0100, Michal Nazarewicz wrote:

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@@ -1017,11 +1049,14 @@ __rmqueue_fallback(struct zone *zone, int order, int start_migratetype) rmv_page_order(page);

	/* Take ownership for orders >= pageblock_order */

• 	if (current_order >= pageblock_order)
  

• 	if (current_order >= pageblock_order &&
  

• 	    !is_pageblock_cma(page))
  	change_pageblock_range(page, current_order,
  				start_migratetype);
  
  

• 	expand(zone, page, order, current_order, area, migratetype);
  

• 	expand(zone, page, order, current_order, area,
  

• 	       is_migrate_cma(start_migratetype)
  

• 	     ? start_migratetype : migratetype);
  
  

What is this check meant to be doing?

start_migratetype is determined by allocflags_to_migratetype() and that never will be MIGRATE_CMA so is_migrate_cma(start_migratetype) should always be false.

Right, thanks! This should be the other way around, ie.:

• 	expand(zone, page, order, current_order, area,
  

• 	       is_migrate_cma(migratetype)
  

• 	     ? migratetype : start_migratetype);
  
  

I'll fix this and the calls to is_pageblock_cma().

That makes a lot more sense. Thanks.

I have a vague recollection that there was a problem with finding unmovable pages in MIGRATE_CMA regions. This might have been part of the problem.