Re: [PATCH v3 2/9] mm/rmap: refactor hugetlb pte clearing in try_to_unmap_one

[Barry Song]

On Mon, May 11, 2026 at 3:10 PM David Hildenbrand (Arm)
<david@xxxxxxxxxx> wrote:
[...]
> > +     *pteval = huge_ptep_clear_flush(vma, pvmw->address, pvmw->pte);
> > +     if (pte_dirty(*pteval))
> > +             folio_mark_dirty(folio);
> > +
> > +     *exit_walk = false;
> > +     return true;
>
>
> Can we instead introduce some enum that tells the caller how to proceed?
>
> I assume we have
>
> (a) Abort walk (ret = false + page_vma_mapped_walk_done())
>
> (b) Walk done (ret = true + page_vma_mapped_walk_done())
>
> (c) Continue walk (call page_vma_mapped_walk())
>
> enum ttu_walk_result {
>         TTU_WALK_CONTINUE,
>         TTU_WALK_ABORT,
>         TTU_WALK_DONE
> }
>
[...]
>
> In the old walk_abort case you wouldn't set ret = false?
>
> When returning the enum you could simply do something like
>
> switch (ret) {
> case TTU_WALK_ABORT:
>         goto walk_abort;
> case TTU_WALK_DONE:
>         goto walk_done;
> default:
>         break;
> }
>

I believe I suggested the exact same approach in v2[1], but Dev didn’t agree :-)

[1] https://lore.kernel.org/linux-mm/CAGsJ_4zK1W71iSP14gi=8yWSg80EjgYiBXqLChB2i+X+RSTWcw@xxxxxxxxxxxxxx/