The patch titled
Subject: mm: vmscan: add validation before spliting shmem large folio
has been added to the -mm mm-unstable branch. Its filename is
mm-vmscan-add-validation-before-spliting-shmem-large-folio.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-vmscan-add-validation-before-spliting-shmem-large-folio.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
Subject: mm: vmscan: add validation before spliting shmem large folio
Date: Tue, 18 Jun 2024 14:54:13 +0800
Patch series "support large folio swap-out and swap-in for shmem", v2.
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.
Functional testing
==================
Machine environment: 32 Arm cores, 120G memory and 50G swap device.
1. Run xfstests suite to test tmpfs filesystem, and I did not catch any
regressions with this patch set.
FSTYP=tmpfs
export TEST_DIR=/mnt/tempfs_mnt
export TEST_DEV=/mnt/tempfs_mnt
export SCRATCH_MNT=/mnt/scratchdir
export SCRATCH_DEV=/mnt/scratchdir
2. Run all mm selftests in tools/testing/selftests/mm/, and no
regressions found.
3. I also wrote several shmem swap test cases, including shmem
splitting, shmem swapout, shmem swapin, swapoff during shmem swapout,
shmem reclaim, shmem swapin replacement, etc. I tested these cases
under 4K and 64K shmem folio sizes with a swap device, and shmem swap
functionality works well on my machine (I can share these test cases if
needed).
[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/
[4] https://lore.kernel.org/all/8db63194-77fd-e0b8-8601-2bbf04889a5b@xxxxxxxxxx/
This patch (of 9):
Add swap available space validation before spliting shmem large folio to
avoid redundant split, since we can not write shmem folio to the swap
device in this case.
Link: https://lkml.kernel.org/r/cover.1718690645.git.baolin.wang@xxxxxxxxxxxxxxxxx
Link: https://lkml.kernel.org/r/413866f2f2d996cfbb5c906467b36c96b1a82e2d.1718690645.git.baolin.wang@xxxxxxxxxxxxxxxxx
Signed-off-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
Cc: Barry Song <21cnbao@xxxxxxxxx>
Cc: Chris Li <chrisl@xxxxxxxxxx>
Cc: Daniel Gomez <da.gomez@xxxxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: "Huang, Ying" <ying.huang@xxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
Cc: Lance Yang <ioworker0@xxxxxxxxx>
Cc: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Cc: Pankaj Raghav <p.raghav@xxxxxxxxxxx>
Cc: Ryan Roberts <ryan.roberts@xxxxxxx>
Cc: Yang Shi <shy828301@xxxxxxxxx>
Cc: Zi Yan <ziy@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/vmscan.c | 8 ++++++++
1 file changed, 8 insertions(+)
--- a/mm/vmscan.c~mm-vmscan-add-validation-before-spliting-shmem-large-folio
+++ a/mm/vmscan.c
@@ -1237,6 +1237,14 @@ retry:
}
} else if (folio_test_swapbacked(folio) &&
folio_test_large(folio)) {
+
+ /*
+ * Do not split shmem folio if no swap memory
+ * available.
+ */
+ if (!total_swap_pages)
+ goto activate_locked;
+
/* Split shmem folio */
if (split_folio_to_list(folio, folio_list))
goto keep_locked;
_
Patches currently in -mm which might be from baolin.wang@xxxxxxxxxxxxxxxxx are
mm-memory-extend-finish_fault-to-support-large-folio.patch
mm-memory-extend-finish_fault-to-support-large-folio-fix.patch
mm-memory-extend-finish_fault-to-support-large-folio-fix-fix.patch
mm-shmem-add-thp-validation-for-pmd-mapped-thp-related-statistics.patch
mm-shmem-add-multi-size-thp-sysfs-interface-for-anonymous-shmem.patch
mm-shmem-add-multi-size-thp-sysfs-interface-for-anonymous-shmem-fix.patch
mm-shmem-add-multi-size-thp-sysfs-interface-for-anonymous-shmem-fix-3.patch
mm-shmem-add-mthp-support-for-anonymous-shmem.patch
mm-shmem-add-mthp-size-alignment-in-shmem_get_unmapped_area.patch
mm-shmem-add-mthp-counters-for-anonymous-shmem.patch
mm-shmem-add-mthp-counters-for-anonymous-shmem-fix.patch
mm-memcontrol-add-vm_bug_on_folio-to-catch-lru-folio-in-mem_cgroup_migrate.patch
mm-vmscan-add-validation-before-spliting-shmem-large-folio.patch
mm-swap-extend-swap_shmem_alloc-to-support-batch-swap_map_shmem-flag-setting.patch
mm-shmem-extend-shmem_partial_swap_usage-to-support-large-folio-swap.patch
mm-filemap-use-xa_get_order-to-get-the-swap-entry-order.patch
mm-shmem-use-swap_free_nr-to-free-shmem-swap-entries.patch
mm-shmem-support-large-folio-allocation-for-shmem_replace_folio.patch
mm-shmem-drop-folio-reference-count-using-nr_pages-in-shmem_delete_from_page_cache.patch
mm-shmem-support-large-folio-swap-out.patch
