On Sat, May 08, 2021 at 11:55:33AM +0800, Ding Hui wrote: > Recently we found there is a lot MemFree left in /proc/meminfo after > do a lot of pages soft offline. > > I think it's incorrect since NR_FREE_PAGES should not contain HWPoison pages. > For offline free pages, after a successful call take_page_off_buddy(), the > page is no longer belong to buddy allocator, and will not be used any more, > but we missed accounting NR_FREE_PAGES in this situation. > > Do update like rmqueue() does. > > Signed-off-by: Ding Hui <dinghui@xxxxxxxxxxxxxx> > --- > V2: > use __mod_zone_freepage_state instead of __mod_zone_page_state > > mm/page_alloc.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index cfc72873961d..e124a615303b 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -8947,6 +8947,7 @@ bool take_page_off_buddy(struct page *page) > del_page_from_free_list(page_head, zone, page_order); > break_down_buddy_pages(zone, page_head, page, 0, > page_order, migratetype); > + __mod_zone_freepage_state(zone, -1, migratetype); Page offline code (see set_migratetype_isolate()) seems to handle NR_FREE_PAGES counter in its own way, so I think that it's more correct to call __mod_zone_freepage_state() only when is_migrate_isolate(migratetype)) is false. Otherwise, the patch looks good to me. Thanks, Naoya Horiguchi > ret = true; > break; > } > -- > 2.17.1 >
