Re: [PATCH v3 32/40] mm/uffd: use predicates for userfaultfd checks

[Zi Yan]

On Thu Sep 17, 2026 at 12:22 PM EDT, Lorenzo Stoakes (ARM) wrote:
> Rather than directly checking VMA flags, use the newly introduced
> vma_is_kernel_owned() and vma_is_persistent() helpers in userfaultfd when
> assessing VMA suitability for userfaultfd and UFFDIO_MOVE.
>
> Update vma_move_compatible() so it's expressed in terms of VMA
> characteristics rather than arbitrary flags.
>
> Additionally, update the use of the deprecated VMA flag API when checking
> VMA_SHADOW_STACK_BIT.
>
> A VMA_IO_BIT check is no longer required but that is fine as a hard
> invariant has been established that only kernel-owned mappings may set
> VMA_IO_BIT so the check is now redundant.
>
> Signed-off-by: Lorenzo Stoakes (ARM) <ljs@xxxxxxxxxx>
> ---
>  mm/userfaultfd.c | 21 +++++++++++++++------
>  1 file changed, 15 insertions(+), 6 deletions(-)
>
LGTM.

Acked-by: Zi Yan <ziy@xxxxxxxxxx>


-- 
Best Regards,
Yan, Zi