The patch titled
Subject: mm/truncate: make sure folio2 is large and has the same mapping after lock
has been added to the -mm mm-unstable branch. Its filename is
mm-truncate-use-buddy-allocator-like-folio-split-for-truncate-operation-fix.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-truncate-use-buddy-allocator-like-folio-split-for-truncate-operation-fix.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: Zi Yan <ziy@xxxxxxxxxx>
Subject: mm/truncate: make sure folio2 is large and has the same mapping after lock
Date: Sat, 1 Mar 2025 22:34:24 -0500
It is possible that folio2 no longer belongs to the original mapping.
Link: https://lkml.kernel.org/r/56EBE3B6-99EA-470E-B2B3-92C9C13032DF@xxxxxxxxxx
Signed-off-by: Zi Yan <ziy@xxxxxxxxxx>
Cc: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: John Hubbard <jhubbard@xxxxxxxxxx>
Cc: Kairui Song <kasong@xxxxxxxxxxx>
Cc: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
Cc: Kirill A. Shuemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Cc: Ryan Roberts <ryan.roberts@xxxxxxx>
Cc: Yang Shi <yang@xxxxxxxxxxxxxxxxxxxxxx>
Cc: Yu Zhao <yuzhao@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/truncate.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
--- a/mm/truncate.c~mm-truncate-use-buddy-allocator-like-folio-split-for-truncate-operation-fix
+++ a/mm/truncate.c
@@ -244,8 +244,14 @@ bool truncate_inode_partial_folio(struct
if (!folio_trylock(folio2))
goto out;
- /* split result does not matter here */
- try_folio_split(folio2, split_at2, NULL);
+ /*
+ * make sure folio2 is large and does not change its mapping.
+ * Its split result does not matter here.
+ */
+ if (folio_test_large(folio2) &&
+ folio2->mapping == folio->mapping)
+ try_folio_split(folio2, split_at2, NULL);
+
folio_unlock(folio2);
out:
folio_put(folio2);
_
Patches currently in -mm which might be from ziy@xxxxxxxxxx are
selftests-mm-make-file-backed-thp-split-work-by-writing-pmd-size-data.patch
mm-huge_memory-allow-split-shmem-large-folio-to-any-lower-order.patch
selftests-mm-test-splitting-file-backed-thp-to-any-lower-order.patch
xarray-add-xas_try_split-to-split-a-multi-index-entry.patch
mm-huge_memory-add-two-new-not-yet-used-functions-for-folio_split.patch
mm-huge_memory-move-folio-split-common-code-to-__folio_split.patch
mm-huge_memory-add-buddy-allocator-like-non-uniform-folio_split.patch
mm-huge_memory-remove-the-old-unused-__split_huge_page.patch
mm-huge_memory-add-folio_split-to-debugfs-testing-interface.patch
mm-truncate-use-buddy-allocator-like-folio-split-for-truncate-operation.patch
mm-truncate-use-buddy-allocator-like-folio-split-for-truncate-operation-fix.patch
selftests-mm-add-tests-for-folio_split-buddy-allocator-like-split.patch
mm-filemap-use-xas_try_split-in-__filemap_add_folio.patch
mm-shmem-use-xas_try_split-in-shmem_split_large_entry.patch
