On Thu, 6 Jun 2024, Baolin Wang wrote: > 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] series is queued into mm-unstable branch. > Hence this patch set also supports the large folio swap-out and swap-in for > shmem. > > [1] https://lore.kernel.org/all/cover.1717495894.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/ > > Changes from RFC: > - Rebased to the latest mm-unstable. > - Drop the counter name fixing patch, which was queued into mm-hotfixes-stable > branch. > > Baolin Wang (7): > 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/shmem.c | 58 ++++++++------ > mm/swapfile.c | 98 ++++++++++++----------- > mm/truncate.c | 8 +- > mm/vmscan.c | 22 ++++- > 9 files changed, 140 insertions(+), 83 deletions(-) I wanted to have some tests running, while looking through these and your shmem mTHP patches; but I wasted too much time on that by applying these on top and hitting crash, OOMs and dreadful thrashing - testing did not get very far at all. Perhaps all easily fixed, but I don't have more time to spend on it, and think this series cannot expect to go into 6.11: I'll have another try with it next cycle. I really must turn my attention to your shmem mTHP series: no doubt I'll have minor adjustments to ask there - but several other people are also waiting for me to respond (or given up on me completely). The little crash fix needed in this series appears to be: --- a/mm/shmem.c +++ b/mm/shmem.c @@ -2053,7 +2053,8 @@ static int shmem_swapin_folio(struct ino goto failed; } - error = shmem_add_to_page_cache(folio, mapping, index, + error = shmem_add_to_page_cache(folio, mapping, + round_down(index, nr_pages), swp_to_radix_entry(swap), gfp); if (error) goto failed; Then the OOMs and dreadful thrashing are due to refcount confusion: I did not even glance at these patches to work out what's wanted, but a printk in __remove_mapping() showed that folio->_refcount was 1024 where 513 was expected, so reclaim was freeing none of them. Hugh
