+ ocfs2-avoid-potential-abba-deadlock-by-reordering-tl_inode-lock.patch added to mm-nonmm-unstable branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: ocfs2: avoid potential ABBA deadlock by reordering tl_inode lock
has been added to the -mm mm-nonmm-unstable branch.  Its filename is
     ocfs2-avoid-potential-abba-deadlock-by-reordering-tl_inode-lock.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/ocfs2-avoid-potential-abba-deadlock-by-reordering-tl_inode-lock.patch

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

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------------------------------------------------------
From: Ivan Pravdin <ipravdin.official@gmail.com>
Subject: ocfs2: avoid potential ABBA deadlock by reordering tl_inode lock
Date: Mon, 7 Jul 2025 22:06:40 -0400

In ocfs2_move_extent(), tl_inode is currently locked after the global
bitmap inode.  However, in ocfs2_flush_truncate_log(), the lock order is
reversed: tl_inode is locked first, followed by the global bitmap inode.

This creates a classic ABBA deadlock scenario if two threads attempt these
operations concurrently and acquire the locks in different orders.

To prevent this, move the tl_inode locking earlier in ocfs2_move_extent(),
so that it always precedes the global bitmap inode lock.

No functional changes beyond lock ordering.

Link: https://lkml.kernel.org/r/20250708020640.387741-1-ipravdin.official@gmail.com
Reported-by: syzbot+6bf948e47f9bac7aacfa@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/all/67d5645c.050a0220.1dc86f.0004.GAE@google.com/
Signed-off-by: Ivan Pravdin <ipravdin.official@gmail.com>
Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Jun Piao <piaojun@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 fs/ocfs2/move_extents.c |   19 +++++++++----------
 1 file changed, 9 insertions(+), 10 deletions(-)

--- a/fs/ocfs2/move_extents.c~ocfs2-avoid-potential-abba-deadlock-by-reordering-tl_inode-lock
+++ a/fs/ocfs2/move_extents.c
@@ -617,6 +617,8 @@ static int ocfs2_move_extent(struct ocfs
 	 */
 	credits += OCFS2_INODE_UPDATE_CREDITS + 1;
 
+	inode_lock(tl_inode);
+
 	/*
 	 * ocfs2_move_extent() didn't reserve any clusters in lock_allocators()
 	 * logic, while we still need to lock the global_bitmap.
@@ -626,7 +628,7 @@ static int ocfs2_move_extent(struct ocfs
 	if (!gb_inode) {
 		mlog(ML_ERROR, "unable to get global_bitmap inode\n");
 		ret = -EIO;
-		goto out;
+		goto out_unlock_tl_inode;
 	}
 
 	inode_lock(gb_inode);
@@ -634,16 +636,14 @@ static int ocfs2_move_extent(struct ocfs
 	ret = ocfs2_inode_lock(gb_inode, &gb_bh, 1);
 	if (ret) {
 		mlog_errno(ret);
-		goto out_unlock_gb_mutex;
+		goto out_unlock_gb_inode;
 	}
 
-	inode_lock(tl_inode);
-
 	handle = ocfs2_start_trans(osb, credits);
 	if (IS_ERR(handle)) {
 		ret = PTR_ERR(handle);
 		mlog_errno(ret);
-		goto out_unlock_tl_inode;
+		goto out_unlock;
 	}
 
 	new_phys_blkno = ocfs2_clusters_to_blocks(inode->i_sb, *new_phys_cpos);
@@ -703,15 +703,14 @@ static int ocfs2_move_extent(struct ocfs
 out_commit:
 	ocfs2_commit_trans(osb, handle);
 	brelse(gd_bh);
-
-out_unlock_tl_inode:
-	inode_unlock(tl_inode);
-
+out_unlock:
 	ocfs2_inode_unlock(gb_inode, 1);
-out_unlock_gb_mutex:
+out_unlock_gb_inode:
 	inode_unlock(gb_inode);
 	brelse(gb_bh);
 	iput(gb_inode);
+out_unlock_tl_inode:
+	inode_unlock(tl_inode);
 
 out:
 	if (context->meta_ac) {
_

Patches currently in -mm which might be from ipravdin.official@gmail.com are

ocfs2-avoid-null-pointer-dereference-in-dx_dir_lookup_rec.patch
ocfs2-avoid-potential-abba-deadlock-by-reordering-tl_inode-lock.patch