On 2015년 08월 05일 08:31, Minchan Kim wrote: > Hello, > > On Tue, Aug 04, 2015 at 03:09:37PM -0700, Andrew Morton wrote: >> On Tue, 04 Aug 2015 19:40:08 +0900 Jaewon Kim <jaewon31.kim@xxxxxxxxxxx> wrote: >> >>> reclaim_clean_pages_from_list() assumes that shrink_page_list() returns >>> number of pages removed from the candidate list. But shrink_page_list() >>> puts back mlocked pages without passing it to caller and without >>> counting as nr_reclaimed. This incurrs increasing nr_isolated. >>> To fix this, this patch changes shrink_page_list() to pass unevictable >>> pages back to caller. Caller will take care those pages. >>> >>> .. >>> >>> --- a/mm/vmscan.c >>> +++ b/mm/vmscan.c >>> @@ -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; >>> >>> activate_locked: >> >> Is this going to cause a whole bunch of mlocked pages to be migrated >> whereas in current kernels they stay where they are? >> > > It fixes two issues. > > 1. With unevictable page, cma_alloc will be successful. > > Exactly speaking, cma_alloc of current kernel will fail due to unevictable pages. > > 2. fix leaking of NR_ISOLATED counter of vmstat > > With it, too_many_isolated works. Otherwise, it could make hang until > the process get SIGKILL. > > So, I think it's stable material. > > Acked-by: Minchan Kim <minchan@xxxxxxxxxx> > > > Hello Traditional shrink_inactive_list will put back the unevictable pages as it does through putback_inactive_pages. However as Minchan Kim said, cma_alloc will be more successful by migrating unevictable pages. In current kernel, I think, cma_alloc is already trying to migrate unevictable pages except clean page cache. This patch will allow clean page cache also to be migrated in cma_alloc. Thank you -- 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>