6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Yun Zhou [ Upstream commit 41a28c865d1d5843f8cb9e0af17a8f4d9e2961ff ] xfs_sync_sb_buf() holds sb/rtsb buffer locks across a synchronous xfs_trans_commit(), which flushes the CIL push workqueue internally. If shutdown occurs during the CIL push, xfs_buf_item_unpin() needs to lock these buffers to fail them, causing a deadlock: setlabel: holds buf lock -> flush_workqueue(xfs-cil) CIL push worker: xfs_buf_item_unpin -> xfs_buf_lock(same buf) Remove the xfs_trans_bhold() calls so that commit releases the buffer locks normally. After the sync commit, re-acquire the buffers via mp->m_sb_bp / mp->m_rtsb_bp for the on-disk writeback. Fixes: f7664b31975b ("xfs: implement online get/set fs label") Reported-by: syzbot+837bcd54843dd6262f2f@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=837bcd54843dd6262f2f Cc: stable@vger.kernel.org Signed-off-by: Yun Zhou Reviewed-by: Christoph Hellwig Signed-off-by: Carlos Maiolino [ sashal: Omitted realtime-superblock changes because the corresponding support is absent. ] Signed-off-by: Sasha Levin --- fs/xfs/libxfs/xfs_sb.c | 17 +++++++---------- 1 file changed, 7 insertions(+), 10 deletions(-) diff --git a/fs/xfs/libxfs/xfs_sb.c b/fs/xfs/libxfs/xfs_sb.c index eb46712e27d9f..de10b1adbf8a5 100644 --- a/fs/xfs/libxfs/xfs_sb.c +++ b/fs/xfs/libxfs/xfs_sb.c @@ -1186,26 +1186,23 @@ xfs_sync_sb_buf( struct xfs_mount *mp) { struct xfs_trans *tp; - struct xfs_buf *bp; int error; error = xfs_trans_alloc(mp, &M_RES(mp)->tr_sb, 0, 0, 0, &tp); if (error) return error; - bp = xfs_trans_getsb(tp); xfs_log_sb(tp); - xfs_trans_bhold(tp, bp); xfs_trans_set_sync(tp); error = xfs_trans_commit(tp); if (error) - goto out; - /* - * write out the sb buffer to get the changes to disk - */ - error = xfs_bwrite(bp); -out: - xfs_buf_relse(bp); + return error; + + /* Re-acquire and write the sb to disk. */ + xfs_buf_lock(mp->m_sb_bp); + error = xfs_bwrite(mp->m_sb_bp); + xfs_buf_unlock(mp->m_sb_bp); + return error; } -- 2.53.0