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    SubjectRe: [PATCH v2 17/39] mm: Fixup places that call pte_mkwrite() directly
    On Thu, Sep 29, 2022 at 03:29:14PM -0700, Rick Edgecombe wrote:
    > diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c
    > index 7327b2573f7c..b49372c7de41 100644
    > --- a/mm/userfaultfd.c
    > +++ b/mm/userfaultfd.c
    > @@ -63,6 +63,7 @@ int mfill_atomic_install_pte(struct mm_struct *dst_mm, pmd_t *dst_pmd,
    > int ret;
    > pte_t _dst_pte, *dst_pte;
    > bool writable = dst_vma->vm_flags & VM_WRITE;
    > + bool shstk = dst_vma->vm_flags & VM_SHADOW_STACK;
    > bool vm_shared = dst_vma->vm_flags & VM_SHARED;
    > bool page_in_cache = page->mapping;
    > spinlock_t *ptl;
    > @@ -83,9 +84,12 @@ int mfill_atomic_install_pte(struct mm_struct *dst_mm, pmd_t *dst_pmd,
    > writable = false;
    > }
    >
    > - if (writable)
    > - _dst_pte = pte_mkwrite(_dst_pte);
    > - else
    > + if (writable) {
    > + if (shstk)
    > + _dst_pte = pte_mkwrite_shstk(_dst_pte);
    > + else
    > + _dst_pte = pte_mkwrite(_dst_pte);
    > + } else
    > /*
    > * We need this to make sure write bit removed; as mk_pte()
    > * could return a pte with write bit set.

    Urgh.. that's unfortunate. But yeah, I don't see a way to make that
    pretty either.

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