On Mon, Jan 30, 2012 at 11:48:20AM +0000, Mel Gorman wrote: > > + if (!zone) > > + zone = page_zone(pfn_to_page(pfn)); > > + else if (zone != page_zone(pfn_to_page(pfn))) > > + break; > > + > > So what you are checking for here is if you straddle zones. > You could just initialise zone outside of the for loop. You can > then check outside the loop if end_pfn is in a different zone to > start_pfn. If it is, either adjust end_pfn accordingly or bail the > entire operation avoiding the need for release_freepages() later. This > will be a little cheaper. > Whoops, silly me! You are watching for overlapping zones which can happen in some rare configurations and for that checking page_zone() like this is necessary. You can still initialise zone outside the loop but the page_zone() check is still necessary. My bad. -- Mel Gorman SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>