The patch below does not apply to the 6.12-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.12.y git checkout FETCH_HEAD git cherry-pick -x 14efb4793519d73fb2902bb0ece319b886e4b4b9 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2025032430-granny-hunter-c6a5@gregkh' --subject-prefix 'PATCH 6.12.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 14efb4793519d73fb2902bb0ece319b886e4b4b9 Mon Sep 17 00:00:00 2001 From: Zi Yan ziy@nvidia.com Date: Mon, 10 Mar 2025 11:57:27 -0400 Subject: [PATCH] mm/huge_memory: drop beyond-EOF folios with the right number of refs

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

diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 3d3ebdc002d5..373781b21e5c 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -3304,7 +3304,7 @@ static void __split_huge_page(struct page *page, struct list_head *list, 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);