The patch titled Subject: mm/huge_memory: drop beyond-EOF folios with the right number of refs. has been added to the -mm mm-hotfixes-unstable branch. Its filename is mm-huge_memory-drop-beyond-eof-folios-with-the-right-number-of-refs.patch
This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches...
This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------ From: Zi Yan ziy@nvidia.com Subject: mm/huge_memory: drop beyond-EOF folios with the right number of refs. Date: Mon, 10 Mar 2025 11:57:27 -0400
When an after-split folio is large and needs to be dropped due to EOF, folio_put_refs(folio, folio_nr_pages(folio)) should be used to drop all page cache refs. Otherwise, the folio will not be freed, causing memory leak.
This leak would happen on a filesystem with blocksize > page_size and a truncate is performed, where the blocksize makes folios split to >0 order ones, causing truncated folios not being freed.
Link: https://lkml.kernel.org/r/20250310155727.472846-1-ziy@nvidia.com Fixes: c010d47f107f ("mm: thp: split huge page to any lower order pages") Signed-off-by: Zi Yan ziy@nvidia.com Reported-by: Hugh Dickins hughd@google.com Closes: https://lore.kernel.org/all/fcbadb7f-dd3e-21df-f9a7-2853b53183c4@google.com/ Cc: Baolin Wang baolin.wang@linux.alibaba.com Cc: David Hildenbrand david@redhat.com Cc: John Hubbard jhubbard@nvidia.com Cc: Kefeng Wang wangkefeng.wang@huawei.com Cc: Kirill A. Shuemov kirill.shutemov@linux.intel.com Cc: Luis Chamberalin mcgrof@kernel.org Cc: Matthew Wilcow (Oracle) willy@infradead.org Cc: Miaohe Lin linmiaohe@huawei.com Cc: Pankaj Raghav p.raghav@samsung.com Cc: Ryan Roberts ryan.roberts@arm.com Cc: Yang Shi yang@os.amperecomputing.com Cc: Yu Zhao yuzhao@google.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---
mm/huge_memory.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/mm/huge_memory.c~mm-huge_memory-drop-beyond-eof-folios-with-the-right-number-of-refs +++ a/mm/huge_memory.c @@ -3304,7 +3304,7 @@ static void __split_huge_page(struct pag folio_account_cleaned(tail, inode_to_wb(folio->mapping->host)); __filemap_remove_folio(tail, NULL); - folio_put(tail); + folio_put_refs(tail, folio_nr_pages(tail)); } else if (!folio_test_anon(folio)) { __xa_store(&folio->mapping->i_pages, tail->index, tail, 0); _
Patches currently in -mm which might be from ziy@nvidia.com are
mm-migrate-fix-shmem-xarray-update-during-migration.patch mm-huge_memory-drop-beyond-eof-folios-with-the-right-number-of-refs.patch 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-add-two-new-not-yet-used-functions-for-folio_split-fix.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-folio_split-in-truncate-operation.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