On Wed, Apr 29, 2026 at 11:35:32AM -0400, Zi Yan wrote: >After READ_ONLY_THP_FOR_FS is removed, FS either supports large folio or >not. folio_split() can be used on a FS with large folio support without >worrying about getting a THP on a FS without large folio support. > >When READ_ONLY_THP_FOR_FS was present, a PMD large pagecache folio can >appear in a FS without large folio support after khugepaged or >madvise(MADV_COLLAPSE) creates it. During truncate_inode_partial_folio(), >such a PMD large pagecache folio is split and if the FS does not support >large folio, it needs to be split to order-0 ones and could not be split >non uniformly to ones with various orders. try_folio_split_to_order() was >added to handle this situation by checking folio_check_splittable(..., >SPLIT_TYPE_NON_UNIFORM) to detect if the large folio is created due to >READ_ONLY_THP_FOR_FS and the FS does not support large folio. Now >READ_ONLY_THP_FOR_FS is removed, all large pagecache folios are created >with FSes supporting large folio, this function is no longer needed and all >large pagecache folios can be split non uniformly. > >Signed-off-by: Zi Yan <[email protected]> >---
With that gone, large page-cache folios should only exsit on mappings that support large folios, so folio_split() with mapping_min_folio_order() is enough :) LGTM, feel free to add: Reviewed-by: Lance Yang <[email protected]>
