On 3/27/26 02:42, Zi Yan wrote: > Hi all, > > This patchset removes READ_ONLY_THP_FOR_FS Kconfig and enables creating > read-only THPs for FSes with large folio support (the supported orders > need to include PMD_ORDER) by default. > > The changes are: > 1. collapse_file() from mm/khugepaged.c, instead of checking > CONFIG_READ_ONLY_THP_FOR_FS, makes sure the mapping_max_folio_order() > of struct address_space of the file is at least PMD_ORDER. > 2. file_thp_enabled() also checks mapping_max_folio_order() instead. > 3. truncate_inode_partial_folio() calls folio_split() directly instead > of the removed try_folio_split_to_order(), since large folios can > only show up on a FS with large folio support. > 4. nr_thps is removed from struct address_space, since it is no longer > needed to drop all read-only THPs from a FS without large folio > support when the fd becomes writable. Its related filemap_nr_thps*() > are removed too. > 5. folio_check_splittable() no longer checks READ_ONLY_THP_FOR_FS. > 6. Updated comments in various places. > > Changelog > === > From RFC[1]: > 1. instead of removing READ_ONLY_THP_FOR_FS function entirely, turn it > on by default for all FSes with large folio support and the supported > orders includes PMD_ORDER. > > Suggestions and comments are welcome.
Hi! :) The patch set might be better structured by 1) Teaching code paths to not only respect READ_ONLY_THP_FOR_FS but also filesystems with large folios. At that point, READ_ONLY_THP_FOR_FS would have no effect. 2) Removing READ_ONLY_THP_FOR_FS along with all the old cruft that is no longer required MADV_COLLAPSE will keep working the whole time. -- Cheers, David
