======================================================
WARNING: possible circular locking dependency detected
6.6.0-rc4-syzkaller-00173-g776fe19953b0 #0 Not tainted
------------------------------------------------------
kworker/u5:2/9368 is trying to acquire lock:
ffff88801ef18078 (&hdev->lock){+.+.}-{3:3}, at: discov_off+0x8c/0x1d0 net/bluetooth/mgmt.c:1055

but task is already holding lock:
ffffc9000bf67d80 ((work_completion)(&(&hdev->discov_off)->work)){+.+.}-{0:0}, at: process_one_work+0x7e9/0x15c0 kernel/workqueue.c:2606

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}:
       __flush_work+0x103/0xa10 kernel/workqueue.c:3403
       __cancel_work_timer+0x3ef/0x580 kernel/workqueue.c:3494
       mgmt_index_removed+0x1ed/0x350 net/bluetooth/mgmt.c:9436
       hci_unregister_dev+0x472/0x600 net/bluetooth/hci_core.c:2743
       vhci_release+0x7f/0x100 drivers/bluetooth/hci_vhci.c:669
       __fput+0x3f7/0xa70 fs/file_table.c:384
       task_work_run+0x14d/0x240 kernel/task_work.c:180
       exit_task_work include/linux/task_work.h:38 [inline]
       do_exit+0xa92/0x2a20 kernel/exit.c:874
       do_group_exit+0xd4/0x2a0 kernel/exit.c:1024
       __do_sys_exit_group kernel/exit.c:1035 [inline]
       __se_sys_exit_group kernel/exit.c:1033 [inline]
       __x64_sys_exit_group+0x3e/0x50 kernel/exit.c:1033
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x63/0xcd

-> #0 (&hdev->lock){+.+.}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3134 [inline]
       check_prevs_add kernel/locking/lockdep.c:3253 [inline]
       validate_chain kernel/locking/lockdep.c:3868 [inline]
       __lock_acquire+0x2e3d/0x5de0 kernel/locking/lockdep.c:5136
       lock_acquire kernel/locking/lockdep.c:5753 [inline]
       lock_acquire+0x1ae/0x510 kernel/locking/lockdep.c:5718
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x181/0x1340 kernel/locking/mutex.c:747
       discov_off+0x8c/0x1d0 net/bluetooth/mgmt.c:1055
       process_one_work+0x884/0x15c0 kernel/workqueue.c:2630
       process_scheduled_works kernel/workqueue.c:2703 [inline]
       worker_thread+0x8b9/0x1290 kernel/workqueue.c:2784
       kthread+0x33c/0x440 kernel/kthread.c:388
       ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
       ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304

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/u5:2/9368:
 #0: ffff888018240538 ((wq_completion)hci0){+.+.}-{0:0}, at: process_one_work+0x787/0x15c0 kernel/workqueue.c:2605
 #1: ffffc9000bf67d80 ((work_completion)(&(&hdev->discov_off)->work)){+.+.}-{0:0}, at: process_one_work+0x7e9/0x15c0 kernel/workqueue.c:2606

stack backtrace:
CPU: 1 PID: 9368 Comm: kworker/u5:2 Not tainted 6.6.0-rc4-syzkaller-00173-g776fe19953b0 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/06/2023
Workqueue: hci0 discov_off
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xd9/0x1b0 lib/dump_stack.c:106
 check_noncircular+0x311/0x3f0 kernel/locking/lockdep.c:2187
 check_prev_add kernel/locking/lockdep.c:3134 [inline]
 check_prevs_add kernel/locking/lockdep.c:3253 [inline]
 validate_chain kernel/locking/lockdep.c:3868 [inline]
 __lock_acquire+0x2e3d/0x5de0 kernel/locking/lockdep.c:5136
 lock_acquire kernel/locking/lockdep.c:5753 [inline]
 lock_acquire+0x1ae/0x510 kernel/locking/lockdep.c:5718
 __mutex_lock_common kernel/locking/mutex.c:603 [inline]
 __mutex_lock+0x181/0x1340 kernel/locking/mutex.c:747
 discov_off+0x8c/0x1d0 net/bluetooth/mgmt.c:1055
 process_one_work+0x884/0x15c0 kernel/workqueue.c:2630
 process_scheduled_works kernel/workqueue.c:2703 [inline]
 worker_thread+0x8b9/0x1290 kernel/workqueue.c:2784
 kthread+0x33c/0x440 kernel/kthread.c:388
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304
 </TASK>