======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.6.141/5248 is trying to acquire lock:
ffff888072829028
 ((work_completion)(&hdev->bg_scan_update)
){+.+.}-{0:0}, at: __flush_work+0xfa/0x210 kernel/workqueue.c:3090

but task is already holding lock:
ffffffff8e4d7308 (rfkill_global_mutex){+.+.}-{3:3}
, at: rfkill_fop_write+0x1ae/0x560 net/rfkill/core.c:1279

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #4 (rfkill_global_mutex){+.+.}-{3:3}:
       __mutex_lock_common+0x1e5/0x2400 kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
       rfkill_register+0x2f/0x970 net/rfkill/core.c:1060
       hci_register_dev+0x459/0x980 net/bluetooth/hci_core.c:3987
       __vhci_create_device drivers/bluetooth/hci_vhci.c:129 [inline]
       vhci_create_device+0x32e/0x5c0 drivers/bluetooth/hci_vhci.c:153
       vhci_get_user drivers/bluetooth/hci_vhci.c:210 [inline]
       vhci_write+0x389/0x440 drivers/bluetooth/hci_vhci.c:290
       call_write_iter include/linux/fs.h:2179 [inline]
       new_sync_write fs/read_write.c:507 [inline]
       vfs_write+0x748/0xd70 fs/read_write.c:594
       ksys_write+0x153/0x260 fs/read_write.c:647
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

-> #3
 (&data->open_mutex
){+.+.}-{3:3}
:
       __mutex_lock_common+0x1e5/0x2400 kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
       vhci_send_frame+0x88/0x100 drivers/bluetooth/hci_vhci.c:71
       hci_send_frame+0x1a9/0x2e0 net/bluetooth/hci_core.c:4286
       hci_sched_acl_pkt net/bluetooth/hci_core.c:4811 [inline]
       hci_sched_acl net/bluetooth/hci_core.c:4896 [inline]
       hci_tx_work+0x9b5/0x16d0 net/bluetooth/hci_core.c:4962
       process_one_work+0x867/0xff0 kernel/workqueue.c:2310
       worker_thread+0xad7/0x12a0 kernel/workqueue.c:2457
       kthread+0x42e/0x520 kernel/kthread.c:334
       ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287

-> #2 ((work_completion)(&hdev->tx_work)){+.+.}-{0:0}
:
       __flush_work+0x116/0x210 kernel/workqueue.c:3090
       hci_dev_do_close+0x201/0x1020 net/bluetooth/hci_core.c:1774
       hci_unregister_dev+0x2eb/0x590 net/bluetooth/hci_core.c:4070
       vhci_release+0x73/0xc0 drivers/bluetooth/hci_vhci.c:345
       __fput+0x212/0x8c0 fs/file_table.c:311
       task_work_run+0x125/0x1a0 kernel/task_work.c:188
       exit_task_work include/linux/task_work.h:33 [inline]
       do_exit+0x635/0x2110 kernel/exit.c:890
       do_group_exit+0x12c/0x2f0 kernel/exit.c:1004
       __do_sys_exit_group kernel/exit.c:1015 [inline]
       __se_sys_exit_group kernel/exit.c:1013 [inline]
       __x64_sys_exit_group+0x3b/0x40 kernel/exit.c:1013
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

-> #1 (
&hdev->req_lock){+.+.}-{3:3}
:
       __mutex_lock_common+0x1e5/0x2400 kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
       hci_req_sync net/bluetooth/hci_request.c:278 [inline]
       bg_scan_update+0x44/0x3b0 net/bluetooth/hci_request.c:2952
       process_one_work+0x867/0xff0 kernel/workqueue.c:2310
       worker_thread+0xad7/0x12a0 kernel/workqueue.c:2457
       kthread+0x42e/0x520 kernel/kthread.c:334
       ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287

-> #0 (
(work_completion)(&hdev->bg_scan_update)
){+.+.}-{0:0}
:
       check_prev_add kernel/locking/lockdep.c:3120 [inline]
       check_prevs_add kernel/locking/lockdep.c:3239 [inline]
       validate_chain kernel/locking/lockdep.c:3855 [inline]
       __lock_acquire+0x38f7/0x7d40 kernel/locking/lockdep.c:5120
       lock_acquire+0x19f/0x400 kernel/locking/lockdep.c:5737
       __flush_work+0x116/0x210 kernel/workqueue.c:3090
       __cancel_work_timer+0x3f4/0x560 kernel/workqueue.c:3181
       hci_request_cancel_all+0xcc/0x300 net/bluetooth/hci_request.c:3522
       hci_dev_do_close+0x4e/0x1020 net/bluetooth/hci_core.c:1754
       hci_rfkill_set_block+0x101/0x180 net/bluetooth/hci_core.c:2253
       rfkill_set_block+0x1c1/0x3c0 net/rfkill/core.c:360
       rfkill_fop_write+0x453/0x560 net/rfkill/core.c:1287
       vfs_write+0x304/0xd70 fs/read_write.c:592
       ksys_write+0x153/0x260 fs/read_write.c:647
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

other info that might help us debug this:

Chain exists of:
  
(work_completion)(&hdev->bg_scan_update) --> &data->open_mutex --> rfkill_global_mutex


 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(
rfkill_global_mutex
);
                               lock(
&data->open_mutex);
                               lock(rfkill_global_mutex);
  lock((work_completion)(&hdev->bg_scan_update));

 *** DEADLOCK ***

1 lock held by syz.6.141/5248:
 #0: ffffffff8e4d7308
 (rfkill_global_mutex
){+.+.}-{3:3}, at: rfkill_fop_write+0x1ae/0x560 net/rfkill/core.c:1279

stack backtrace:
CPU: 1 PID: 5248 Comm: syz.6.141 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
 check_noncircular+0x2f8/0x400 kernel/locking/lockdep.c:2178
 check_prev_add kernel/locking/lockdep.c:3120 [inline]
 check_prevs_add kernel/locking/lockdep.c:3239 [inline]
 validate_chain kernel/locking/lockdep.c:3855 [inline]
 __lock_acquire+0x38f7/0x7d40 kernel/locking/lockdep.c:5120
 lock_acquire+0x19f/0x400 kernel/locking/lockdep.c:5737
 __flush_work+0x116/0x210 kernel/workqueue.c:3090
 __cancel_work_timer+0x3f4/0x560 kernel/workqueue.c:3181
 hci_request_cancel_all+0xcc/0x300 net/bluetooth/hci_request.c:3522
 hci_dev_do_close+0x4e/0x1020 net/bluetooth/hci_core.c:1754
 hci_rfkill_set_block+0x101/0x180 net/bluetooth/hci_core.c:2253
 rfkill_set_block+0x1c1/0x3c0 net/rfkill/core.c:360
 rfkill_fop_write+0x453/0x560 net/rfkill/core.c:1287
 vfs_write+0x304/0xd70 fs/read_write.c:592
 ksys_write+0x153/0x260 fs/read_write.c:647
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f7bef9f01d9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f7bedc48028 EFLAGS: 00000246
 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f7befc77fa0 RCX: 00007f7bef9f01d9
RDX: 0000000000000008 RSI: 0000200000000980 RDI: 0000000000000003
RBP: 00007f7befa87888 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f7befc78038 R14: 00007f7befc77fa0 R15: 00007ffc424f3b48
 </TASK>
hci4: cancelling interleave scan
hci4 state 0 -> 0
All LE pending actions cleared
hdev hci4
hcon ffff888062488000 reason 22
hcon ffff888062488000 conn ffff888062482800, err 103
hci4 hcon ffff888062488000 chan ffff888026617400
hci4 hcon ffff888062488000 handle 201
hcon ffff888062488000
hci4: conn ffff888062488000
device: 'hci4:201': device_unregister
kernfs runtime_status: removing
kernfs control: removing
kernfs runtime_suspended_time: removing
kernfs runtime_active_time: removing
kernfs autosuspend_delay_ms: removing
kernfs power: removing
kernfs device: removing
kernfs subsystem: removing
kernfs hci4:201: removing
kernfs uevent: removing
PM: Removing info for No Bus:hci4:201
kobject: 'hci4:201' (ffff888062488420): kobject_uevent_env
kobject: 'hci4:201' (ffff888062488420): fill_kobj_path: path = '/devices/virtual/bluetooth/hci4/hci4:201'
kernfs hci4:201: removing
kobject: 'hci4:201' (ffff888062488420): kobject_cleanup, parent 0000000000000000
kobject: 'hci4:201' (ffff888062488420): calling ktype release
kobject: 'hci4:201': free name
hci4 orig refcnt 10
hcon ffff888074f54000 reason 22
hcon ffff888074f54000 conn ffff888062482000, err 103
hci4 hcon ffff888074f54000 chan ffff888026617200
hci4 hcon ffff888074f54000 handle 200
hcon ffff888074f54000
hci4: conn ffff888074f54000
device: 'hci4:200': device_unregister
kernfs runtime_status: removing
kernfs control: removing
kernfs runtime_suspended_time: removing
kernfs runtime_active_time: removing
kernfs autosuspend_delay_ms: removing
kernfs power: removing
kernfs device: removing
kernfs subsystem: removing
kernfs hci4:200: removing
kernfs uevent: removing
PM: Removing info for No Bus:hci4:200
kobject: 'hci4:200' (ffff888074f54420): kobject_uevent_env
kobject: 'hci4:200' (ffff888074f54420): fill_kobj_path: path = '/devices/virtual/bluetooth/hci4/hci4:200'
kernfs hci4:200: removing
kobject: 'hci4:200' (ffff888074f54420): kobject_cleanup, parent 0000000000000000
kobject: 'hci4:200' (ffff888074f54420): calling ktype release
kobject: 'hci4:200': free name
hci4 orig refcnt 7
hdev hci4 event 4
hdev 0000000000000000 len 8
hdev hci4 event 8
hci4 orig refcnt 6
kobject: 'rfkill9' (ffff88814c95a108): kobject_uevent_env
kobject: 'rfkill9' (ffff88814c95a108): fill_kobj_path: path = '/devices/virtual/bluetooth/hci4/rfkill9'
ffff88805c280000 name hci3 blocked 1
hci3 ffff88805c280000
hci3: err 0x13
hci3: cancelling interleave scan
hci3 state 0 -> 0
All LE pending actions cleared
hdev hci3
hcon ffff88802cebe000 reason 22
hcon ffff88802cebe000 conn ffff88802bb5c000, err 103
hci3 hcon ffff88802cebe000 chan ffff88805a1aaa00
hci3 hcon ffff88802cebe000 handle 201
hcon ffff88802cebe000
hci3: conn ffff88802cebe000
device: 'hci3:201': device_unregister
kernfs runtime_status: removing
kernfs control: removing
kernfs runtime_suspended_time: removing
kernfs runtime_active_time: removing
kernfs autosuspend_delay_ms: removing
kernfs power: removing
kernfs device: removing
kernfs subsystem: removing
kernfs hci3:201: removing
kernfs uevent: removing
PM: Removing info for No Bus:hci3:201
kobject: 'hci3:201' (ffff88802cebe420): kobject_uevent_env
kobject: 'hci3:201' (ffff88802cebe420): fill_kobj_path: path = '/devices/virtual/bluetooth/hci3/hci3:201'
kernfs hci3:201: removing
kobject: 'hci3:201' (ffff88802cebe420): kobject_cleanup, parent 0000000000000000
kobject: 'hci3:201' (ffff88802cebe420): calling ktype release
kobject: 'hci3:201': free name
hci3 orig refcnt 10
hcon ffff88802c408000 reason 22
hcon ffff88802c408000 conn ffff88802bb5c800, err 103
hci3 hcon ffff88802c408000 chan ffff88805a1aa900
hci3 hcon ffff88802c408000 handle 200
hcon ffff88802c408000
hci3: conn ffff88802c408000
device: 'hci3:200': device_unregister
kernfs runtime_status: removing
kernfs control: removing
kernfs runtime_suspended_time: removing
kernfs runtime_active_time: removing
kernfs autosuspend_delay_ms: removing
kernfs power: removing
kernfs device: removing
kernfs subsystem: removing
kernfs hci3:200: removing
kernfs uevent: removing
PM: Removing info for No Bus:hci3:200
kobject: 'hci3:200' (ffff88802c408420): kobject_uevent_env
kobject: 'hci3:200' (ffff88802c408420): fill_kobj_path: path = '/devices/virtual/bluetooth/hci3/hci3:200'
kernfs hci3:200: removing
kobject: 'hci3:200' (ffff88802c408420): kobject_cleanup, parent 0000000000000000
kobject: 'hci3:200' (ffff88802c408420): calling ktype release
kobject: 'hci3:200': free name
hci3 orig refcnt 7
hdev hci3 event 4
hdev 0000000000000000 len 8
hdev hci3 event 8
hci3 orig refcnt 6
kobject: 'rfkill20' (ffff888020045108): kobject_uevent_env
kobject: 'rfkill20' (ffff888020045108): fill_kobj_path: path = '/devices/virtual/bluetooth/hci3/rfkill20'
ffff888066adc000 name hci2 blocked 1
hci2 ffff888066adc000
hci2: err 0x13
hci2: cancelling interleave scan
hci2 state 0 -> 0
All LE pending actions cleared
hdev hci2
hcon ffff888079d98000 reason 22
hcon ffff888079d98000 conn ffff88801e739000, err 103
hci2 hcon ffff888079d98000 chan ffff8880752f6c00
hci2 hcon ffff888079d98000 handle 201
hcon ffff888079d98000
hci2: conn ffff888079d98000
device: 'hci2:201': device_unregister
kernfs runtime_status: removing
kernfs control: removing
kernfs runtime_suspended_time: removing
kernfs runtime_active_time: removing
kernfs autosuspend_delay_ms: removing
kernfs power: removing
kernfs device: removing
kernfs subsystem: removing
kernfs hci2:201: removing
kernfs uevent: removing
PM: Removing info for No Bus:hci2:201
kobject: 'hci2:201' (ffff888079d98420): kobject_uevent_env
kobject: 'hci2:201' (ffff888079d98420): fill_kobj_path: path = '/devices/virtual/bluetooth/hci2/hci2:201'
kernfs hci2:201: removing
kobject: 'hci2:201' (ffff888079d98420): kobject_cleanup, parent 0000000000000000
kobject: 'hci2:201' (ffff888079d98420): calling ktype release
kobject: 'hci2:201': free name
hci2 orig refcnt 10
hcon ffff888079796000 reason 22
hcon ffff888079796000 conn ffff88801e739800, err 103
hci2 hcon ffff888079796000 chan ffff8880752f6800
hci2 hcon ffff888079796000 handle 200
hcon ffff888079796000
hci2: conn ffff888079796000
device: 'hci2:200': device_unregister
kernfs runtime_status: removing
kernfs control: removing
kernfs runtime_suspended_time: removing
kernfs runtime_active_time: removing
kernfs autosuspend_delay_ms: removing
kernfs power: removing
kernfs device: removing
kernfs subsystem: removing
kernfs hci2:200: removing
kernfs uevent: removing
PM: Removing info for No Bus:hci2:200
kobject: 'hci2:200' (ffff888079796420): kobject_uevent_env
kobject: 'hci2:200' (ffff888079796420): fill_kobj_path: path = '/devices/virtual/bluetooth/hci2/hci2:200'
kernfs hci2:200: removing
kobject: 'hci2:200' (ffff888079796420): kobject_cleanup, parent 0000000000000000
kobject: 'hci2:200' (ffff888079796420): calling ktype release
kobject: 'hci2:200': free name
hci2 orig refcnt 7
hdev hci2 event 4
hdev 0000000000000000 len 8
hdev hci2 event 8
hci2 orig refcnt 6
kobject: 'rfkill21' (ffff888020ad8108): kobject_uevent_env
kobject: 'rfkill21' (ffff888020ad8108): fill_kobj_path: path = '/devices/virtual/bluetooth/hci2/rfkill21'
ffff888029920000 name hci0 blocked 1
hci0 ffff888029920000
hci0: err 0x13
hci0: cancelling interleave scan