syzbot

======================================================
WARNING: possible circular locking dependency detected
6.2.0-rc2-syzkaller-00282-g0a71553536d2 #0 Not tainted
------------------------------------------------------
kworker/u5:0/21970 is trying to acquire lock:
ffff88803c228078 (&hdev->lock){+.+.}-{3:3}, at: discov_off+0x8c/0x1a0 net/bluetooth/mgmt.c:1037

but task is already holding lock:
ffffc9000316fda8 ((work_completion)(&(&hdev->discov_off)->work)){+.+.}-{0:0}, at: process_one_work+0x8a1/0x1710 kernel/workqueue.c:2264

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+0x109/0xaf0 kernel/workqueue.c:3069
       __cancel_work_timer+0x3f9/0x570 kernel/workqueue.c:3160
       mgmt_index_removed+0x21c/0x340 net/bluetooth/mgmt.c:9432
       hci_unregister_dev+0x39e/0x580 net/bluetooth/hci_core.c:2708
       vhci_release+0x80/0xf0 drivers/bluetooth/hci_vhci.c:568
       __fput+0x27c/0xa90 fs/file_table.c:320
       task_work_run+0x16f/0x270 kernel/task_work.c:179
       exit_task_work include/linux/task_work.h:38 [inline]
       do_exit+0xaa8/0x2950 kernel/exit.c:867
       do_group_exit+0xd4/0x2a0 kernel/exit.c:1012
       get_signal+0x21c3/0x2450 kernel/signal.c:2859
       arch_do_signal_or_restart+0x79/0x5c0 arch/x86/kernel/signal.c:306
       exit_to_user_mode_loop kernel/entry/common.c:168 [inline]
       exit_to_user_mode_prepare+0x15f/0x250 kernel/entry/common.c:203
       __syscall_exit_to_user_mode_work kernel/entry/common.c:285 [inline]
       syscall_exit_to_user_mode+0x1d/0x50 kernel/entry/common.c:296
       do_syscall_64+0x46/0xb0 arch/x86/entry/common.c:86
       entry_SYSCALL_64_after_hwframe+0x63/0xcd

-> #0 (&hdev->lock){+.+.}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3097 [inline]
       check_prevs_add kernel/locking/lockdep.c:3216 [inline]
       validate_chain kernel/locking/lockdep.c:3831 [inline]
       __lock_acquire+0x2a43/0x56d0 kernel/locking/lockdep.c:5055
       lock_acquire kernel/locking/lockdep.c:5668 [inline]
       lock_acquire+0x1e3/0x630 kernel/locking/lockdep.c:5633
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x12f/0x1360 kernel/locking/mutex.c:747
       discov_off+0x8c/0x1a0 net/bluetooth/mgmt.c:1037
       process_one_work+0x9bf/0x1710 kernel/workqueue.c:2289
       worker_thread+0x669/0x1090 kernel/workqueue.c:2436
       kthread+0x2e8/0x3a0 kernel/kthread.c:376
       ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308

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/u5:0/21970:
 #0: ffff888075622938 ((wq_completion)hci0){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
 #0: ffff888075622938 ((wq_completion)hci0){+.+.}-{0:0}, at: arch_atomic_long_set include/linux/atomic/atomic-long.h:41 [inline]
 #0: ffff888075622938 ((wq_completion)hci0){+.+.}-{0:0}, at: atomic_long_set include/linux/atomic/atomic-instrumented.h:1280 [inline]
 #0: ffff888075622938 ((wq_completion)hci0){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:636 [inline]
 #0: ffff888075622938 ((wq_completion)hci0){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:663 [inline]
 #0: ffff888075622938 ((wq_completion)hci0){+.+.}-{0:0}, at: process_one_work+0x86d/0x1710 kernel/workqueue.c:2260
 #1: ffffc9000316fda8 ((work_completion)(&(&hdev->discov_off)->work)){+.+.}-{0:0}, at: process_one_work+0x8a1/0x1710 kernel/workqueue.c:2264

stack backtrace:
CPU: 0 PID: 21970 Comm: kworker/u5:0 Not tainted 6.2.0-rc2-syzkaller-00282-g0a71553536d2 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
Workqueue: hci0 discov_off
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xd1/0x138 lib/dump_stack.c:106
 check_noncircular+0x25f/0x2e0 kernel/locking/lockdep.c:2177
 check_prev_add kernel/locking/lockdep.c:3097 [inline]
 check_prevs_add kernel/locking/lockdep.c:3216 [inline]
 validate_chain kernel/locking/lockdep.c:3831 [inline]
 __lock_acquire+0x2a43/0x56d0 kernel/locking/lockdep.c:5055
 lock_acquire kernel/locking/lockdep.c:5668 [inline]
 lock_acquire+0x1e3/0x630 kernel/locking/lockdep.c:5633
 __mutex_lock_common kernel/locking/mutex.c:603 [inline]
 __mutex_lock+0x12f/0x1360 kernel/locking/mutex.c:747
 discov_off+0x8c/0x1a0 net/bluetooth/mgmt.c:1037
 process_one_work+0x9bf/0x1710 kernel/workqueue.c:2289
 worker_thread+0x669/0x1090 kernel/workqueue.c:2436
 kthread+0x2e8/0x3a0 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308
 </TASK>