On Mon, Feb 02, 2026 at 05:13:20PM -0500, Peter Xu wrote:
> On Tue, Jan 27, 2026 at 09:29:28PM +0200, Mike Rapoport wrote:
>
> [...]
>
> > -static int mfill_atomic_pte_zeroed_folio(pmd_t *dst_pmd,
> > - struct vm_area_struct *dst_vma,
> > - unsigned long dst_addr)
> > +static int mfill_atomic_pte_copy(struct mfill_state *state)
> > {
> > - struct folio *folio;
> > - int ret = -ENOMEM;
> > -
> > - folio = vma_alloc_zeroed_movable_folio(dst_vma, dst_addr);
> > - if (!folio)
> > - return ret;
> > -
> > - if (mem_cgroup_charge(folio, dst_vma->vm_mm, GFP_KERNEL))
> > - goto out_put;
> > + const struct vm_uffd_ops *ops = vma_uffd_ops(state->vma);
> >
> > - /*
> > - * The memory barrier inside __folio_mark_uptodate makes sure that
> > - * zeroing out the folio become visible before mapping the page
> > - * using set_pte_at(). See do_anonymous_page().
> > - */
> > - __folio_mark_uptodate(folio);
> > + return __mfill_atomic_pte(state, ops);
> > +}
> >
> > - ret = mfill_atomic_install_pte(dst_pmd, dst_vma, dst_addr,
> > - &folio->page, true, 0);
> > - if (ret)
> > - goto out_put;
> > +static int mfill_atomic_pte_zeroed_folio(struct mfill_state *state)
> > +{
> > + const struct vm_uffd_ops *ops = vma_uffd_ops(state->vma);
> >
> > - return 0;
> > -out_put:
> > - folio_put(folio);
> > - return ret;
> > + return __mfill_atomic_pte(state, ops);
> > }
> >
> > static int mfill_atomic_pte_zeropage(struct mfill_state *state)
> > @@ -542,7 +546,7 @@ static int mfill_atomic_pte_zeropage(struct mfill_state
> > *state)
> > int ret;
> >
> > if (mm_forbids_zeropage(dst_vma->vm_mm))
> > - return mfill_atomic_pte_zeroed_folio(dst_pmd, dst_vma,
> > dst_addr);
> > + return mfill_atomic_pte_zeroed_folio(state);
>
> After this patch, mfill_atomic_pte_zeroed_folio() should be 100% the same
> impl with mfill_atomic_pte_copy(), so IIUC we can drop it.
It will be slightly different after the next patch to emphasize that
copying into MAP_PRIVATE actually creates anonymous memory.
> > _dst_pte = pte_mkspecial(pfn_pte(my_zero_pfn(dst_addr),
> > dst_vma->vm_page_prot));
> > --
> > 2.51.0
> >
>
> --
> Peter Xu
>
--
Sincerely yours,
Mike.
