On Sep 14, 2022, at 03:54, Doug Berger [off-list ref] wrote:

With gigantic pages it may not be true that struct page structures
are contiguous across the entire gigantic page. The mem_map_offset
function is used here in place of direct pointer arithmetic to
correct for this.

Fixes: 8531fc6f52f5 ("hugetlb: add hugetlb demote page support")
Signed-off-by: Doug Berger <opendmb@gmail.com>

With Matthew’s suggestion.

Acked-by: Muchun Song <redacted>

Thanks.