======================================================
WARNING: possible circular locking dependency detected
6.6.0-syzkaller-15892-g3185d57cfcd3 #0 Not tainted
------------------------------------------------------
syz-executor.0/5084 is trying to acquire lock:
ffff8880543b4ae0 ((work_completion)(&(&hdev->discov_off)->work)){+.+.}-{0:0}, at: __flush_work+0xfa/0xa10 kernel/workqueue.c:3403

but task is already holding lock:
ffff8880543b4078 (&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+0x175/0x9d0 kernel/locking/mutex.c:747
       discov_off+0x8c/0x1d0 net/bluetooth/mgmt.c:1055
       process_one_work+0x886/0x15d0 kernel/workqueue.c:2630
       process_scheduled_works kernel/workqueue.c:2703 [inline]
       worker_thread+0x8b9/0x1290 kernel/workqueue.c:2784
       kthread+0x2c6/0x3a0 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+0x2464/0x3b10 kernel/locking/lockdep.c:5136
       lock_acquire kernel/locking/lockdep.c:5753 [inline]
       lock_acquire+0x1ae/0x520 kernel/locking/lockdep.c:5718
       __flush_work+0x103/0xa10 kernel/workqueue.c:3403
       __cancel_work_timer+0x3ef/0x590 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+0x14d/0x240 kernel/task_work.c:180
       exit_task_work include/linux/task_work.h:38 [inline]
       do_exit+0xa92/0x2ae0 kernel/exit.c:871
       do_group_exit+0xd4/0x2a0 kernel/exit.c:1021
       __do_sys_exit_group kernel/exit.c:1032 [inline]
       __se_sys_exit_group kernel/exit.c:1030 [inline]
       __x64_sys_exit_group+0x3e/0x50 kernel/exit.c:1030
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x40/0x110 arch/x86/entry/common.c:82
       entry_SYSCALL_64_after_hwframe+0x63/0x6b

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.0/5084:
 #0: ffff8880543b4078 (&hdev->lock){+.+.}-{3:3}, at: hci_unregister_dev+0x46a/0x600 net/bluetooth/hci_core.c:2744

stack backtrace:
CPU: 1 PID: 5084 Comm: syz-executor.0 Not tainted 6.6.0-syzkaller-15892-g3185d57cfcd3 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/10/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xd9/0x1b0 lib/dump_stack.c:106
 check_noncircular+0x317/0x400 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+0x2464/0x3b10 kernel/locking/lockdep.c:5136
 lock_acquire kernel/locking/lockdep.c:5753 [inline]
 lock_acquire+0x1ae/0x520 kernel/locking/lockdep.c:5718
 __flush_work+0x103/0xa10 kernel/workqueue.c:3403
 __cancel_work_timer+0x3ef/0x590 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+0x14d/0x240 kernel/task_work.c:180
 exit_task_work include/linux/task_work.h:38 [inline]
 do_exit+0xa92/0x2ae0 kernel/exit.c:871
 do_group_exit+0xd4/0x2a0 kernel/exit.c:1021
 __do_sys_exit_group kernel/exit.c:1032 [inline]
 __se_sys_exit_group kernel/exit.c:1030 [inline]
 __x64_sys_exit_group+0x3e/0x50 kernel/exit.c:1030
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x40/0x110 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x63/0x6b
RIP: 0033:0x7ff59c07cae9
Code: Unable to access opcode bytes at 0x7ff59c07cabf.
RSP: 002b:00007ffd3ac52dd8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007ff59c07cae9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000043
RBP: 00007ff59c0c844b R08: 00007ffd3ac50b76 R09: 000000000012db44
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000000001c
R13: 000000000012db44 R14: 000000000012d61c R15: 000000000000001e
 </TASK>