Re: [PATCH v1 05/18] mm: improve folio_likely_mapped_shared() using the mapcount of large folios
David Hildenbrand <[email protected]>
| Newsgroups | gmane.linux.documentation,gmane.linux.kernel,gmane.linux.kernel.mm,gmane.linux.kernel.cgroups,gmane.linux.ports.sh.devel,gmane.linux.file-systems |
|---|---|
| Organization | Red Hat |
| Message-ID | <[email protected]> |
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