+ mm-shmem-avoid-unpaired-folio_unlock-in-shmem_swapin_folio.patch added to mm-new branch

+ mm-shmem-avoid-unpaired-folio_unlock-in-shmem_swapin_folio.patch added to mm-new branch

[Andrew Morton]

The patch titled
     Subject: mm: shmem: avoid unpaired folio_unlock() in shmem_swapin_folio()
has been added to the -mm mm-new branch.  Its filename is
     mm-shmem-avoid-unpaired-folio_unlock-in-shmem_swapin_folio.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-shmem-avoid-unpaired-folio_unlock-in-shmem_swapin_folio.patch

This patch will later appear in the mm-new branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Note, mm-new is a provisional staging ground for work-in-progress
patches, and acceptance into mm-new is a notification for others take
notice and to finish up reviews.  Please do not hesitate to respond to
review feedback and post updated versions to replace or incrementally
fixup patches in mm-new.

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------------------------------------------------------
From: Kemeng Shi <shikemeng@huaweicloud.com>
Subject: mm: shmem: avoid unpaired folio_unlock() in shmem_swapin_folio()
Date: Sat, 17 May 2025 01:09:35 +0800

Patch series "Some random fixes and cleanup to shmem", v3.

This series contains some simple fixes and cleanup which are made during
learning shmem.  More details can be found in respective patches.


This patch (of 5):

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: 058313515d5aa ("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>
---

 mm/shmem.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/mm/shmem.c~mm-shmem-avoid-unpaired-folio_unlock-in-shmem_swapin_folio
+++ a/mm/shmem.c
@@ -2335,6 +2335,8 @@ 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 -mm which might be from shikemeng@huaweicloud.com are

mm-shmem-avoid-unpaired-folio_unlock-in-shmem_swapin_folio.patch
mm-shmem-add-missing-shmem_unacct_size-in-__shmem_file_setup.patch
mm-shmem-fix-potential-dead-loop-in-shmem_unuse.patch
mm-shmem-only-remove-inode-from-swaplist-when-its-swapped-page-count-is-0.patch
mm-shmem-remove-unneeded-xa_is_value-check-in-shmem_unuse_swap_entries.patch