======================================================
WARNING: possible circular locking dependency detected
6.6.0-next-20231103-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.0/32185 is trying to acquire lock:
ffff888052db8ae0 ((work_completion)(&(&hdev->discov_off)->work)){+.+.}-{0:0}, at: __flush_work+0xfa/0xa10 kernel/workqueue.c:3403

but task is already holding lock:
ffff888052db8078 (&hdev->lock){+.+.}-{3:3}, at: hci_unregister_dev+0x46a/0x600 net/bluetooth/hci_core.c:2744

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&hdev->lock){+.+.}-{3:3}:
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x181/0x1330 kernel/locking/mutex.c:747
       discov_off+0x8c/0x1d0 net/bluetooth/mgmt.c:1055
       process_one_work+0x8a2/0x15e0 kernel/workqueue.c:2630
       process_scheduled_works kernel/workqueue.c:2703 [inline]
       worker_thread+0x8b6/0x1280 kernel/workqueue.c:2784
       kthread+0x337/0x440 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:242

-> #0 ((work_completion)(&(&hdev->discov_off)->work)){+.+.}-{0:0}:
       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+0x2e22/0x5dc0 kernel/locking/lockdep.c:5136
       lock_acquire kernel/locking/lockdep.c:5753 [inline]
       lock_acquire+0x1b1/0x530 kernel/locking/lockdep.c:5718
       __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:2745
       vhci_release+0x7f/0x100 drivers/bluetooth/hci_vhci.c:672
       __fput+0x270/0xbb0 fs/file_table.c:394
       task_work_run+0x14c/0x240 kernel/task_work.c:180
       exit_task_work include/linux/task_work.h:38 [inline]
       do_exit+0xa85/0x2ac0 kernel/exit.c:871
       do_group_exit+0xd3/0x2a0 kernel/exit.c:1021
       get_signal+0x2391/0x2760 kernel/signal.c:2904
       arch_do_signal_or_restart+0x90/0x7e0 arch/x86/kernel/signal.c:309
       exit_to_user_mode_loop kernel/entry/common.c:168 [inline]
       exit_to_user_mode_prepare+0x11c/0x240 kernel/entry/common.c:204
       __syscall_exit_to_user_mode_work kernel/entry/common.c:285 [inline]
       syscall_exit_to_user_mode+0x1d/0x60 kernel/entry/common.c:296
       do_syscall_64+0x4b/0x110 arch/x86/entry/common.c:88
       entry_SYSCALL_64_after_hwframe+0x62/0x6a

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&hdev->lock);
                               lock((work_completion)(&(&hdev->discov_off)->work));
                               lock(&hdev->lock);
  lock((work_completion)(&(&hdev->discov_off)->work));

 *** DEADLOCK ***

1 lock held by syz-executor.0/32185:
 #0: ffff888052db8078 (&hdev->lock){+.+.}-{3:3}, at: hci_unregister_dev+0x46a/0x600 net/bluetooth/hci_core.c:2744

stack backtrace:
CPU: 0 PID: 32185 Comm: syz-executor.0 Not tainted 6.6.0-next-20231103-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/09/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xd9/0x1b0 lib/dump_stack.c:106
 check_noncircular+0x310/0x3f0 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+0x2e22/0x5dc0 kernel/locking/lockdep.c:5136
 lock_acquire kernel/locking/lockdep.c:5753 [inline]
 lock_acquire+0x1b1/0x530 kernel/locking/lockdep.c:5718
 __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:2745
 vhci_release+0x7f/0x100 drivers/bluetooth/hci_vhci.c:672
 __fput+0x270/0xbb0 fs/file_table.c:394
 task_work_run+0x14c/0x240 kernel/task_work.c:180
 exit_task_work include/linux/task_work.h:38 [inline]
 do_exit+0xa85/0x2ac0 kernel/exit.c:871
 do_group_exit+0xd3/0x2a0 kernel/exit.c:1021
 get_signal+0x2391/0x2760 kernel/signal.c:2904
 arch_do_signal_or_restart+0x90/0x7e0 arch/x86/kernel/signal.c:309
 exit_to_user_mode_loop kernel/entry/common.c:168 [inline]
 exit_to_user_mode_prepare+0x11c/0x240 kernel/entry/common.c:204
 __syscall_exit_to_user_mode_work kernel/entry/common.c:285 [inline]
 syscall_exit_to_user_mode+0x1d/0x60 kernel/entry/common.c:296
 do_syscall_64+0x4b/0x110 arch/x86/entry/common.c:88
 entry_SYSCALL_64_after_hwframe+0x62/0x6a
RIP: 0033:0x7febbd8a7ef5
Code: Unable to access opcode bytes at 0x7febbd8a7ecb.
RSP: 002b:00007febbe557010 EFLAGS: 00000293 ORIG_RAX: 00000000000000e6
RAX: fffffffffffffdfc RBX: 00007febbd99c120 RCX: 00007febbd8a7ef5
RDX: 00007febbe557050 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007febbd8c847a R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000000
R13: 000000000000006e R14: 00007febbd99c120 R15: 00007ffc5e4e2308
 </TASK>