>>> Because splitting a folio is really something different than splitting just >>> some >>> compound page (no mapping/pagecache/whatever involved). >> >> Yup. > > It sounds like split_compound_page() gets some love (David, Lorenzo, and > Matthew > all want it). I can add one to mm/page_alloc.c, so that Matthew can build > his patchset on top of it.
In there we should verify that it is neither slab nor a folio. For now, we can only test for folios indirectly by considering the large_rmappable flag and hugetlb page type. Likely we should simply disallow any page type for now (and large_rmappable). -- Cheers, David
