On Wed, Jun 10, 2026 at 4:29 AM Baolin Wang <[email protected]> wrote: > > (Note: this patchset is not targeting v7.2, but posted for early feedback.) > > This is a follow-up patchset for mTHP collapse to support shmem mTHP collapse, > which is based on Nico's patchset[1]. > > The shmem mTHP collapse strategy follows the anonymous mTHP collapse approach: > track present pages via a bitmap while scanning PMD ranges for collapse > candidates, > then use the bitmap after the scan completes to determine the most efficient > mTHP order to collapse to. Built on the basic framework added for anonymous > mTHP collapse, the shmem mTHP collapse implementation is straightforward > (Thanks for Nico's work).
As promised I will review this series :) > > In addition, I have added some anon/shmem mTHP collapse selftests, and now all > khugepaged test cases can pass. Thank you for doing that!! I was just working on adding the anon mTHP selftests. Any chance we can separate out those bits and just send a series for adding anon mTHP selftests without the file-related changes? Then your series adds the bits you need here for shmem collapse? Thank you for doing all the heavy lifting there to generalize those functions :) Cheers, -- Nico > > Note: I have not yet enabled large order collapse for file folios (file folios > currently only support PMD-sized large folio collapse). Although file large > order > collapse would be more straightforward to implement after shmem mTHP collapse > support is added (requiring some changes to file_thp_enabled()), I think this > still need some discussion on whether it is necessary to support other large > orders collapse for file folios. > > Comments are welcome. Thanks. > > Changes from RFC v1: > https://lore.kernel.org/all/[email protected]/ > - Rebase on the new code, and update to use the new functions. > - Add more test cases. > > [1] https://lore.kernel.org/all/[email protected]/ > > Baolin Wang (11): > mm: khugepaged: add max_ptes_none check in collapse_file() > mm: khugepaged: generalize collapse_file() for shmem mTHP support > mm: khugepaged: add an order check for PMD-sized THP statistics > mm: khugepaged: add shmem mTHP collapse support > mm: shmem: run khugepaged for all shmem mTHP orders > mm: khugepaged: allow khugepaged to check all shmem mTHP-sized orders > mm: khugepaged: skip large folios that don't need to be collapsed > selftests: mm: extend the check_huge() to support mTHP check > selftests: mm: move gather_after_split_folio_orders() into vm_util.c > file > selftests: mm: implement the mTHP-sized hugepage check helpers > selftests: mm: add mTHP collapse test cases > > include/linux/shmem_fs.h | 4 +- > mm/khugepaged.c | 174 ++++++++++++---- > mm/shmem.c | 10 +- > .../selftests/mm/folio_split_race_test.c | 2 +- > tools/testing/selftests/mm/khugepaged.c | 195 +++++++++++++----- > .../testing/selftests/mm/prctl_thp_disable.c | 2 +- > tools/testing/selftests/mm/run_vmtests.sh | 4 + > tools/testing/selftests/mm/soft-dirty.c | 2 +- > .../selftests/mm/split_huge_page_test.c | 139 +------------ > tools/testing/selftests/mm/uffd-common.c | 4 +- > tools/testing/selftests/mm/vm_util.c | 184 ++++++++++++++++- > tools/testing/selftests/mm/vm_util.h | 8 +- > 12 files changed, 492 insertions(+), 236 deletions(-) > > -- > 2.47.3 >
