Patch "mm: shmem: avoid unpaired folio_unlock() in shmem_swapin_folio()" has been added to the 6.12-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    mm: shmem: avoid unpaired folio_unlock() in shmem_swapin_folio()

to the 6.12-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     mm-shmem-avoid-unpaired-folio_unlock-in-shmem_swapin_folio.patch
and it can be found in the queue-6.12 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


From hughd@google.com Mon Mar 23 10:37:40 2026
From: Hugh Dickins <hughd@google.com>
Date: Mon, 23 Mar 2026 02:37:35 -0700 (PDT)
Subject: mm: shmem: avoid unpaired folio_unlock() in shmem_swapin_folio()
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Hugh Dickins <hughd@google.com>, Andrew Morton <akpm@linux-foundation.org>,  Baolin Wang <baolin.wang@linux.alibaba.com>, Baoquan He <bhe@redhat.com>,  Barry Song <baohua@kernel.org>, Chris Li <chrisl@kernel.org>,  David Hildenbrand <david@kernel.org>, Dev Jain <dev.jain@arm.com>,  Greg Thelen <gthelen@google.com>, Guenter Roeck <groeck@google.com>,  Kairui Song <kasong@tencent.com>, Kemeng Shi <shikemeng@huaweicloud.com>,  Lance Yang <lance.yang@linux.dev>, Matthew Wilcox <willy@infradead.org>,  Nhat Pham <nphamcs@gmail.com>, linux-mm@kvack.org, stable@vger.kernel.org
Message-ID: <49bbe4fa-b678-1023-db47-99a730e2827f@google.com>

From: Kemeng Shi <shikemeng@huaweicloud.com>

commit e08d5f515613a9860bfee7312461a19f422adb5e upstream.

If we get a folio from swap_cache_get_folio() successfully but encounter a
failure before the folio is locked, we will unlock the folio which was not
previously locked.

Put the folio and set it to NULL when a failure occurs before the folio is
locked to fix the issue.

Link: https://lkml.kernel.org/r/20250516170939.965736-1-shikemeng@huaweicloud.com
Link: https://lkml.kernel.org/r/20250516170939.965736-2-shikemeng@huaweicloud.com
Fixes: 058313515d5a ("mm: shmem: fix potential data corruption during shmem swapin")
Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: Kairui Song <kasong@tencent.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: kernel test robot <oliver.sang@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

[ hughd: removed series cover letter comments ]
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 mm/shmem.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -2198,6 +2198,8 @@ static int shmem_swapin_folio(struct ino
 		 */
 		split_order = shmem_split_large_entry(inode, index, swap, gfp);
 		if (split_order < 0) {
+			folio_put(folio);
+			folio = NULL;
 			error = split_order;
 			goto failed;
 		}


Patches currently in stable-queue which might be from hughd@google.com are

queue-6.12/mm-shmem-swap-improve-cached-mthp-handling-and-fix-potential-hang.patch
queue-6.12/mm-shmem-avoid-unpaired-folio_unlock-in-shmem_swapin_folio.patch
queue-6.12/mm-shmem-swap-avoid-redundant-xarray-lookup-during-swapin.patch
queue-6.12/mm-shmem-fix-potential-data-corruption-during-shmem-swapin.patch