On Fri, Dec 4, 2020 at 12:28 AM David Hildenbrand <david@xxxxxxxxxx> wrote: > > On 03.12.20 17:22, Muchun Song wrote: > > The max order page has no buddy page and never merge to other order. > > So isolating and then freeing it is pointless. And if order == MAX_ORDER > > - 1, then the buddy can actually be a !pfn_valid() in some corner case? > > pfn_valid_within(buddy_pfn) that follows would only catch it on archs > > with holes in zone. Then is_migrate_isolate_page(buddy) might access an > > invalid buddy. So this is also a bug fix. > > > > Fixes: 3c605096d315 ("mm/page_alloc: restrict max order of merging on isolated pageblock") > > As just replied to v1, I don't think this is required and the patch You mean we should remove the Fixes tag? Thanks. > description can be simplified - e.g., stating that we have/had not such > users. > > > -- > Thanks, > > David / dhildenb > -- Yours, Muchun