Re: [PATCH 07/10] mm/hugetlb: tolerate uffd bits set without uffd for PROT_NONE PTEs

[Kiryl Shutsemau]

On Thu, Oct 15, 2026 at 06:07:13PM +0200, David Hildenbrand (Arm) wrote:
> The whole uffd handling when a VMA is unregistered from UFFD is shaky:
> there are still some scenarios where we might have stale uffd PTE bits
> in VMAs no longer registered for UFFD, which confuses other code.
> 
> Let's just tolerate that for now and simply clear the PTE bit. Add a
> TODO to really clean up any uffd leftovers when unregistering a VMA from
> userfaultfd.
> 
> The handling is now more similar to what we have in handle_pte_fault().
> 
> Fixes: 2d427bb01639 ("mm/userfaultfd: add RWP fault delivery and expose UFFDIO_REGISTER_MODE_RWP")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: David Hildenbrand (Arm) <david@xxxxxxxxxx>

Acked-by: Kiryl Shutsemau (Meta) <kas@xxxxxxxxxx>

-- 
  Kiryl Shutsemau / Kirill A. Shutemov