6.12-stable review patch. If anyone has any objections, please let me know.
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From: Zi Yan ziy@nvidia.com
commit 14efb4793519d73fb2902bb0ece319b886e4b4b9 upstream.
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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- mm/huge_memory.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -3224,7 +3224,7 @@ 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 (!PageAnon(page)) { __xa_store(&folio->mapping->i_pages, head[i].index, head + i, 0);