====================================================== WARNING: possible circular locking dependency detected 6.1.56-syzkaller #0 Not tainted ------------------------------------------------------ kworker/u5:0/26165 is trying to acquire lock: ffff8880872c0078 (&hdev->lock){+.+.}-{3:3}, at: discov_off+0x8e/0x1f0 net/bluetooth/mgmt.c:1049 but task is already holding lock: ffffc90004defd20 ((work_completion)(&(&hdev->discov_off)->work)){+.+.}-{0:0}, at: process_one_work+0x7a9/0x11d0 kernel/workqueue.c:2267 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 ((work_completion)(&(&hdev->discov_off)->work)){+.+.}-{0:0}: lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5661 __flush_work+0xfe/0xad0 kernel/workqueue.c:3072 __cancel_work_timer+0x519/0x6a0 kernel/workqueue.c:3163 mgmt_index_removed+0x2f6/0x440 net/bluetooth/mgmt.c:9436 hci_unregister_dev+0x2b4/0x480 net/bluetooth/hci_core.c:2740 vhci_release+0x7f/0xd0 drivers/bluetooth/hci_vhci.c:568 __fput+0x3b7/0x890 fs/file_table.c:320 task_work_run+0x246/0x300 kernel/task_work.c:179 exit_task_work include/linux/task_work.h:38 [inline] do_exit+0xa73/0x26a0 kernel/exit.c:869 do_group_exit+0x202/0x2b0 kernel/exit.c:1019 get_signal+0x16f7/0x17d0 kernel/signal.c:2862 arch_do_signal_or_restart+0xb0/0x1a10 arch/x86/kernel/signal.c:871 exit_to_user_mode_loop+0x6a/0x100 kernel/entry/common.c:168 exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:204 __syscall_exit_to_user_mode_work kernel/entry/common.c:286 [inline] syscall_exit_to_user_mode+0x60/0x270 kernel/entry/common.c:297 ret_from_fork+0x15/0x30 arch/x86/entry/entry_64.S:299 -> #0 (&hdev->lock){+.+.}-{3:3}: check_prev_add kernel/locking/lockdep.c:3090 [inline] check_prevs_add kernel/locking/lockdep.c:3209 [inline] validate_chain+0x1667/0x58e0 kernel/locking/lockdep.c:3824 __lock_acquire+0x125b/0x1f80 kernel/locking/lockdep.c:5048 lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5661 __mutex_lock_common kernel/locking/mutex.c:603 [inline] __mutex_lock+0x132/0xd80 kernel/locking/mutex.c:747 discov_off+0x8e/0x1f0 net/bluetooth/mgmt.c:1049 process_one_work+0x8a9/0x11d0 kernel/workqueue.c:2292 worker_thread+0xa47/0x1200 kernel/workqueue.c:2439 kthread+0x28d/0x320 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306 other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock((work_completion)(&(&hdev->discov_off)->work)); lock(&hdev->lock); lock((work_completion)(&(&hdev->discov_off)->work)); lock(&hdev->lock); *** DEADLOCK *** 2 locks held by kworker/u5:0/26165: #0: ffff8880757d4938 ((wq_completion)hci0){+.+.}-{0:0}, at: process_one_work+0x7a9/0x11d0 kernel/workqueue.c:2267 #1: ffffc90004defd20 ((work_completion)(&(&hdev->discov_off)->work)){+.+.}-{0:0}, at: process_one_work+0x7a9/0x11d0 kernel/workqueue.c:2267 stack backtrace: CPU: 1 PID: 26165 Comm: kworker/u5:0 Not tainted 6.1.56-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/06/2023 Workqueue: hci0 discov_off Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106 check_noncircular+0x2fa/0x3b0 kernel/locking/lockdep.c:2170 check_prev_add kernel/locking/lockdep.c:3090 [inline] check_prevs_add kernel/locking/lockdep.c:3209 [inline] validate_chain+0x1667/0x58e0 kernel/locking/lockdep.c:3824 __lock_acquire+0x125b/0x1f80 kernel/locking/lockdep.c:5048 lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5661 __mutex_lock_common kernel/locking/mutex.c:603 [inline] __mutex_lock+0x132/0xd80 kernel/locking/mutex.c:747 discov_off+0x8e/0x1f0 net/bluetooth/mgmt.c:1049 process_one_work+0x8a9/0x11d0 kernel/workqueue.c:2292 worker_thread+0xa47/0x1200 kernel/workqueue.c:2439 kthread+0x28d/0x320 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306