On Fri, Sep 09, 2022 at 05:24:43PM +0800, Miaohe Lin wrote: > In MIGRATE_ISOLATE case, zone freepage state shouldn't be modified as > caller will take care of it. Add missing is_migrate_isolate() here to > avoid possible unbalanced freepage state. > > Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx> Ok, I gave it some thought and I guess it's safe to assume that this would happen if someone isolates the block, and then we face an MCE failure/soft-offline on a page within that block. take_page_off_buddy break_down_buddy_pages set_page_guard will trigger __mod_zone_freepage_state(), which already had been triggered back when the block was isolated. I think the changelog could grow fatter to better explain the issue. Reviewed-by: Oscar Salvador <osalvador@xxxxxxx> > --- > mm/page_alloc.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index a35ef385d906..94baf33da865 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -873,7 +873,8 @@ static inline bool set_page_guard(struct zone *zone, struct page *page, > INIT_LIST_HEAD(&page->buddy_list); > set_page_private(page, order); > /* Guard pages are not available for any usage */ > - __mod_zone_freepage_state(zone, -(1 << order), migratetype); > + if (!is_migrate_isolate(migratetype)) > + __mod_zone_freepage_state(zone, -(1 << order), migratetype); > > return true; > } > -- > 2.23.0 > -- Oscar Salvador SUSE Labs
