On Tue, Apr 21, 2026 at 03:33:27PM +0100, Kiryl Shutsemau wrote: > > 3) Some other stuff needs a second thought, like > > > > diff --git a/mm/gup.c b/mm/gup.c > > index 8e7dc2c6ee738..08fc18f1290d4 100644 > > --- a/mm/gup.c > > +++ b/mm/gup.c > > @@ -695,7 +695,8 @@ static inline bool can_follow_write_pmd(pmd_t pmd, > > struct page *page, > > /* ... and a write-fault isn't required for other reasons. */ > > if (pmd_needs_soft_dirty_wp(vma, pmd)) > > return false; > > - return !userfaultfd_huge_pmd_wp(vma, pmd); > > + return !userfaultfd_huge_pmd_wp(vma, pmd) && > > + !userfaultfd_huge_pmd_rwp(vma, pmd); > > } > > > > How can a pte be writable and prot_none at the same time? Maybe just > > confused AI > > output that you should carefully double check before sending that out > > officially. > > Note that this path is for !pmd_write() case to begin with. It serves > FOLL_FORCE case. I believe this check is correct: we don't want to allow > to write to such pages even with FOLL_FORCE. > > But looking around, I missed gup_can_follow_protnone() modification. It > has to return false for RWP.
With gup_can_follow_protnone() fixed, the checks in can_follow_write_pmd/pte() are redundant. Will drop them. -- Kiryl Shutsemau / Kirill A. Shutemov
