This is past the deadline, so feel free to ignore. However, ... James Houghton has been working on the concept of HugeTLB High Granularity Mapping (HGM) as discussed here: https://lore.kernel.org/linux-mm/20230218002819.1486479-1-jthoughton@xxxxxxxxxx/ The primary motivation for this work is post-copy live migration of VMs backed by hugetlb pages via userfaultfd. A followup use case is more gracefully handling memory errors/poison on hugetlb pages. As can be seen by the size of James's patch set, the required changes for HGM are a bit complex and involved. This is also complicated the need choosing a 'mapcount strategy' as the previous scheme used by hugetlb will no longer work. A HGM for hugetlbfs session would present the current approach and challenges. While much of the work is confined to hugetlb, there is a bit spill over to other mm areas: specifically page table walking. A discussion on ways to move forward with this effort would be appreciated. -- Mike Kravetz
