Re: [PATCH v3 09/18] mm/huge_memory: move anon_vma and filemap management into split helpers

[Kairui Song]

On Fri, Aug 28, 2026 at 12:36 AM David Hildenbrand (Arm)
<david@xxxxxxxxxx> wrote:
>
> On 8/20/26 20:55, Kairui Song via B4 Relay wrote:
> > From: Kairui Song <kasong@xxxxxxxxxxx>
> >
> > Only anon split needs vma info, and only file split needs the filemap
> > handling. Move the related code into separate helpers so they are
> > genuinely more self-contained.
>
> This patch seems to do more than that, like relocating the
> folio_expected_ref_count check (and duplicating it, which is not so nice).
>
> >
> > Reviewed-by: Zi Yan <ziy@xxxxxxxxxx>
> > Signed-off-by: Kairui Song <kasong@xxxxxxxxxxx>
> > ---
>
> [...]
>
> > -     /*
> > -      * Racy check if we can split the page, before unmap_folio() will
> > -      * split PMDs
> > -      */
> > -     if (folio_expected_ref_count(folio) != folio_ref_count(folio) - 1) {
> > -             ret = -EAGAIN;
> > -             goto out_unlock;
> > -     }
> > -
> > -     if (!is_anon) {
> > -             ret = __folio_split_unmap_and_freeze_file(folio, new_order, split_at, &xas, mapping,
> > -                                                       true, list, split_type);
> > -     } else {
> > +     if (is_anon)
> >               ret = __folio_split_unmap_and_freeze_anon(folio, new_order, split_at, true,
> >                                                         true, list, split_type);
> > -     }
>
> Inverting the conditional seems to produce unnecessary noise in this patch.

Will try to make this look nicer.