On Tue, Oct 25, 2011 at 10:59:37AM +0800, Shaohua Li wrote: > If a huge page is split, all the subpages should live in lru list adjacently > because they should be taken as a whole. > In page split, with current code: > a. if huge page is in lru list, the order is: page, page+HPAGE_PMD_NR-1, > page + HPAGE_PMD_NR-2, ..., page + 1(in lru page reclaim order) > b. otherwise, the order is: page, ..other pages.., page + 1, page + 2, ...(in > lru page reclaim order). page + 1 ... page + HPAGE_PMD_NR - 1 are in the lru > reclaim tail. > > In case a, the order is wrong. In case b, page is isolated (to be reclaimed), > but other tail pages will not soon. > > With below patch: > in case a, the order is: page, page + 1, ... page + HPAGE_PMD_NR-1(in lru page > reclaim order). > in case b, the order is: page + 1, ... page + HPAGE_PMD_NR-1 (in lru page reclaim > order). The tail pages are in the lru reclaim head. > > Signed-off-by: Shaohua Li <shaohua.li@xxxxxxxxx> In case of a, it doesn't matter ordering of subpages. As a huge page, age of sub pages are same. In case of b, what a page is located in tail and other subpages are located in head isn't critical problem. Having said that, it's more consistent and simple patch. So I like that. Nice catch, Shaohua! Reviewed-by: Minchan Kim <minchan.kim@xxxxxxxxx> -- Kind regards, Minchan Kim -- 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>