On 4/22/26 11:27, Kiryl Shutsemau wrote: > 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.
Yes, that sounds better. -- Cheers, David
