Re: [PATCH v4 6/6] mm: madvise: Avoid split during MADV_PAGEOUT and MADV_COLD

[David Hildenbrand]

On 20.03.24 14:57, Ryan Roberts wrote:
> On 15/03/2024 10:35, David Hildenbrand wrote:
> > > -        if (!pageout && pte_young(ptent)) {
> > > -            ptent = ptep_get_and_clear_full(mm, addr, pte,
> > > -                            tlb->fullmm);
> > > -            ptent = pte_mkold(ptent);
> > > -            set_pte_at(mm, addr, pte, ptent);
> > > -            tlb_remove_tlb_entry(tlb, pte, addr);
> > > +        if (!pageout) {
> > > +            for (; nr != 0; nr--, pte++, addr += PAGE_SIZE) {
> > > +                if (ptep_test_and_clear_young(vma, addr, pte))
> > > +                    tlb_remove_tlb_entry(tlb, pte, addr);
> > > +            }
> > >            }
> >
> >
> > The following might turn out a bit nicer: Make folio_pte_batch() collect
> > "any_young", then doing something like we do with "any_writable" in the fork()
> > case:
> >
> > ...
> >      nr = folio_pte_batch(folio, addr, pte, ptent, max_nr,
> >                   fpb_flags, NULL, any_young);
> >      if (any_young)
> >          pte_mkyoung(ptent)
> > ...
> >
> > if (!pageout && pte_young(ptent)) {
> >      mkold_full_ptes(mm, addr, pte, nr, tlb->fullmm);
>
> I don't think tlb->fullmm makes sense here because we are not clearing the pte,
> so there is no chance of optimization? So planning to call this mkold_ptes() and
> remove that param. Have I missed something?

Agreed.

--
Cheers,

David / dhildenb