On 25.11.20 12:04, David Hildenbrand wrote: > On 25.11.20 11:39, Mel Gorman wrote: >> On Wed, Nov 25, 2020 at 07:45:30AM +0100, David Hildenbrand wrote: >>>> Something must have changed more recently than v5.1 that caused the >>>> zoneid of reserved pages to be wrong, a possible candidate for the >>>> real would be this change below: >>>> >>>> + __init_single_page(pfn_to_page(pfn), pfn, 0, 0); >>>> >>> >>> Before that change, the memmap of memory holes were only zeroed out. So the >>> zones/nid was 0, however, pages were not reserved and had a refcount of >>> zero - resulting in other issues. >>> >>> Most pfn walkers shouldn???t mess with reserved pages and simply skip them. >>> That would be the right fix here. >>> >> >> Ordinarily yes, pfn walkers should not care about reserved pages but it's >> still surprising that the node/zone linkages would be wrong for memory >> holes. If they are in the middle of a zone, it means that a hole with >> valid struct pages could be mistaken for overlapping nodes (if the hole >> was in node 1 for example) or overlapping zones which is just broken. > > I agree within zones - but AFAIU, the issue is reserved memory between > zones, right?
Double checking, I was confused. This applies also to memory holes within zones in x86. -- Thanks, David / dhildenb
