Hello, On Tue, Aug 04, 2015 at 12:46:57AM +0900, Jaewon Kim wrote: > > > On 2015년 08월 04일 00:33, Minchan Kim wrote: > > On Mon, Aug 03, 2015 at 11:55:46PM +0900, Jaewon Kim wrote: > >> > >> > >> On 2015년 08월 03일 21:27, Minchan Kim wrote: > >>> Hello, > >>> > >>> On Mon, Aug 03, 2015 at 07:18:27PM +0900, Jaewon Kim wrote: > >>>> reclaim_clean_pages_from_list() decreases NR_ISOLATED_FILE by returned > >>>> value from shrink_page_list(). But mlocked pages in the isolated > >>>> clean_pages page list would be removed from the list but not counted as > >>>> nr_reclaimed. Fix this miscounting by returning the number of mlocked > >>>> pages and count it. > >>> > >>> If there are pages not able to reclaim, VM try to migrate it and > >>> have to handle the stat in migrate_pages. > >>> If migrate_pages fails again, putback-fiends should handle it. > >>> > >>> Is there anyting I am missing now? > >>> > >>> Thanks. > >>> > >> Hello > >> > >> Only pages in cc->migratepages will be handled by migrate_pages or > >> putback_movable_pages, and NR_ISOLATED_FILE will be counted properly. > >> However mlocked pages will not be put back into cc->migratepages, > >> and also not be counted in NR_ISOLATED_FILE because putback_lru_page > >> in shrink_page_list does not increase NR_ISOLATED_FILE. > >> The current reclaim_clean_pages_from_list assumes that shrink_page_list > >> returns number of pages removed from the candidate list. > >> > >> i.e) > >> isolate_migratepages_range : NR_ISOLATED_FILE += 10 > >> reclaim_clean_pages_from_list : NR_ISOLATED_FILE -= 5 (1 mlocked page) > >> migrate_pages : NR_ISOLATED_FILE -=4 > >> => NR_ISOLATED_FILE increased by 1 > > > > Thanks for the clarity. > > > > I think the problem is shrink_page_list is awkard. It put back to > > unevictable pages instantly instead of passing it to caller while > > it relies on caller for non-reclaimed-non-unevictable page's putback. > > > > I think we can make it consistent so that shrink_page_list could > > return non-reclaimed pages via page_list and caller can handle it. > > As a bonus, it could try to migrate mlocked pages without retrial. > > > >> > >> Thank you. > > To make clear do you mean changing shrink_page_list like this rather than > previous my suggestion? > > @@ -1157,7 +1157,7 @@ cull_mlocked: > if (PageSwapCache(page)) > try_to_free_swap(page); > unlock_page(page); > - putback_lru_page(page); > + list_add(&page->lru, &ret_pages); > continue; Yes. That's what I said. Thanks. -- 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/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>