On Mon, Jan 30, 2023 at 08:55:03PM +0800, Yin Fengwei wrote:
> +++ b/include/linux/mm.h
> @@ -1061,6 +1061,8 @@ static inline pte_t maybe_mkwrite(pte_t pte, struct vm_area_struct *vma)
>
> vm_fault_t do_set_pmd(struct vm_fault *vmf, struct page *page);
> void do_set_pte(struct vm_fault *vmf, struct page *page, unsigned long addr);
> +void do_set_pte_entry(struct vm_fault *vmf, struct page *page,
> + unsigned long addr);
indentation
> -void do_set_pte(struct vm_fault *vmf, struct page *page, unsigned long addr)
> +void do_set_pte_entry(struct vm_fault *vmf, struct page *page,
> + unsigned long addr)
ditto
> {
> struct vm_area_struct *vma = vmf->vma;
> bool uffd_wp = pte_marker_uffd_wp(vmf->orig_pte);
> @@ -4276,6 +4277,16 @@ void do_set_pte(struct vm_fault *vmf, struct page *page, unsigned long addr)
> entry = maybe_mkwrite(pte_mkdirty(entry), vma);
> if (unlikely(uffd_wp))
> entry = pte_mkuffd_wp(entry);
> + set_pte_at(vma->vm_mm, addr, vmf->pte, entry);
I'm not sure this is safe. As soon as you call set_pte_at(), the page
can be found by GUP. If it is, and it doesn't have rmap set up, aren't
things going to go horribly wrong?
