Re: [PATCH v4 11/14] userfaultfd: add UFFD_FEATURE_RWP_ASYNC for async fault resolution

[Kiryl Shutsemau]

On Mon, May 25, 2026 at 12:36:22PM +0000, sashiko-bot@xxxxxxxxxx wrote:
> Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
> - [Critical] Asynchronous UFFD RWP resolution creates invalid
> clean+writable page table entries, violating the software invariant
> that writable PTEs must be dirty.

This is a false alarm. can_change_pte_writable() already handles the
dirty invariant: can_change_shared_pte_writable() requires
pte_dirty(pte) for shared mappings, and
can_change_private_pte_writable() only allows the upgrade for
PageAnonExclusive anon pages where dirty isn't required.

Plus pte_modify() preserves _PAGE_DIRTY via _PAGE_CHG_MASK.

> -- 
> Sashiko AI review · https://sashiko.dev/#/patchset/20260525113737.1942478-1-kas@xxxxxxxxxx?part=11

-- 
  Kiryl Shutsemau / Kirill A. Shutemov