[RFC PATCH 0/8] support large folio swap-out and swap-in for shmem

[Baolin Wang]

Shmem will support large folio allocation [1] [2] to get a better performance,
however, the memory reclaim still splits the precious large folios when trying
to swap-out shmem, which may lead to the memory fragmentation issue and can not
take advantage of the large folio for shmeme.

Moreover, the swap code already supports for swapping out large folio without
split, and large folio swap-in[3] is under reviewing. Hence this patch set also
supports the large folio swap-out and swap-in for shmem.

Note: this patch set is currently just to show some thoughts and gather some
suggestionsis, and it is based on Barry's large folio swap-in patch set [3] and
my anon shmem mTHP patch set [1].

[1] https://lore.kernel.org/all/cover.1715571279.git.baolin.wang@xxxxxxxxxxxxxxxxx/
[2] https://lore.kernel.org/all/20240515055719.32577-1-da.gomez@xxxxxxxxxxx/
[3] https://lore.kernel.org/all/20240508224040.190469-6-21cnbao@xxxxxxxxx/T/

Baolin Wang (8):
  mm: fix shmem swapout statistic
  mm: vmscan: add validation before spliting shmem large folio
  mm: swap: extend swap_shmem_alloc() to support batch SWAP_MAP_SHMEM
    flag setting
  mm: shmem: support large folio allocation for shmem_replace_folio()
  mm: shmem: extend shmem_partial_swap_usage() to support large folio
    swap
  mm: add new 'orders' parameter for find_get_entries() and
    find_lock_entries()
  mm: shmem: use swap_free_nr() to free shmem swap entries
  mm: shmem: support large folio swap out

 drivers/gpu/drm/i915/gem/i915_gem_shmem.c |  1 +
 include/linux/swap.h                      |  4 +-
 include/linux/writeback.h                 |  1 +
 mm/filemap.c                              | 27 ++++++-
 mm/internal.h                             |  4 +-
 mm/page_io.c                              |  4 +-
 mm/shmem.c                                | 59 ++++++++------
 mm/swapfile.c                             | 98 ++++++++++++-----------
 mm/truncate.c                             |  8 +-
 mm/vmscan.c                               | 22 ++++-
 10 files changed, 143 insertions(+), 85 deletions(-)

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2.39.3