On 7/3/2023 9:24 PM, Zi Yan wrote: > On 2 Jul 2023, at 21:09, Yin, Fengwei wrote: > >> On 7/3/2023 3:51 AM, Zi Yan wrote: >>>> (3) Mapcount of first (or any other) subpage (compount+subpage): for >>>> folio_estimated_sharers(). >>> This is another estimation. I wonder if we can use a different estimation >>> like total_mapcount() > folio_nr_pages() instead. >> Considering the partial folio mapping, I suppose we should use >> total_mapcount() > folio->_nr_pages_mapped >> as folio_estimated_sharers(). > > What you propose is to get a precise check instead of estimate, and you assume no PMD mapping and still require per-page mapcount. > > What I am proposing is to get rid of per-page mapcount, which is my goal, and use a single mapcount to do a rough estimate. O. Sorry. I didn't notice your goal. So if the rough estimate is enough, total_mapcount() > folio_nr_pages() works. Do we need to check all the cases to make sure the rough estimation is enough for all of them? Regards Yin, Fengwei > > -- > Best Regards, > Yan, Zi
