Re: [PATCH v1 05/18] mm: improve folio_likely_mapped_shared() using the mapcount of large folios

[David Hildenbrand]

On 19.04.24 15:47, Yin, Fengwei wrote:
> On 4/19/2024 5:19 PM, David Hildenbrand wrote:
> > On 19.04.24 04:29, Yin, Fengwei wrote:
> > > On 4/10/2024 3:22 AM, David Hildenbrand wrote:
> > > > @@ -2200,7 +2200,22 @@ static inline size_t folio_size(struct folio
> > > > *folio)
> > > >      */
> > > >     static inline bool folio_likely_mapped_shared(struct folio *folio)
> > > >     {
> > > > -    return page_mapcount(folio_page(folio, 0)) > 1;
> > > > +    int mapcount = folio_mapcount(folio);
> > > > +
> > > > +    /* Only partially-mappable folios require more care. */
> > > > +    if (!folio_test_large(folio) ||
> > > > unlikely(folio_test_hugetlb(folio)))
> > > > +        return mapcount > 1;
> > > My understanding is that mapcount > folio_nr_pages(folio) can cover
> > > order 0 folio. And also folio_entire_mapcount() can cover hugetlb (I am
> > > not 100% sure for this one).  I am wondering whether we can drop above
> > > two lines? Thanks.
> >
> > folio_entire_mapcount() does not apply to small folios, so we must not
> > call that for small folios.
> Right. I missed this part. Thanks for clarification.

Thanks for the review!

--
Cheers,

David / dhildenb