Hi, David, Some pure questions below.. On Wed, Aug 09, 2023 at 10:32:56AM +0200, David Hildenbrand wrote: > Let's track the total mapcount for all large folios in the first subpage. > > The total mapcount is what we actually want to know in folio_mapcount() > and it is also sufficient for implementing folio_mapped(). This also > gets rid of any "raceiness" concerns as expressed in > folio_total_mapcount(). Any more information for that "raciness" described here? > > With sub-PMD THP becoming more important and things looking promising > that we will soon get support for such anon THP, we want to avoid looping > over all pages of a folio just to calculate the total mapcount. Further, > we may soon want to use the total mapcount in other context more > frequently, so prepare for reading it efficiently and atomically. Any (perhaps existing) discussion on reduced loops vs added atomic field/ops? I had a feeling that there's some discussion behind the proposal of this patch, if that's the case it'll be great to attach the link in the commit log. Thanks, -- Peter Xu
