======================================================
WARNING: possible circular locking dependency detected
5.10.209 #1 Not tainted
------------------------------------------------------
syz-executor.1/6446 is trying to acquire lock:
ffff888018018ae8 ((work_completion)(&hdev->tx_work)){+.+.}-{0:0}, at: __flush_work+0xdd/0xa90 kernel/workqueue.c:3050

but task is already holding lock:
ffff888018018f40 (&hdev->req_lock){+.+.}-{3:3}, at: hci_dev_do_close+0xef/0x1240 net/bluetooth/hci_core.c:1734

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (&hdev->req_lock){+.+.}-{3:3}:
       __mutex_lock_common kernel/locking/mutex.c:968 [inline]
       __mutex_lock+0x13d/0x10b0 kernel/locking/mutex.c:1109
       hci_dev_do_close+0xef/0x1240 net/bluetooth/hci_core.c:1734
       hci_rfkill_set_block+0x166/0x1a0 net/bluetooth/hci_core.c:2223
       rfkill_set_block+0x1fd/0x540 net/rfkill/core.c:341
       rfkill_fop_write+0x253/0x4b0 net/rfkill/core.c:1240
       vfs_write+0x29a/0xa70 fs/read_write.c:603
       ksys_write+0x1f6/0x260 fs/read_write.c:658
       do_syscall_64+0x33/0x40 arch/x86/entry/common.c:46
       entry_SYSCALL_64_after_hwframe+0x62/0xc7

-> #2 (rfkill_global_mutex){+.+.}-{3:3}:
       __mutex_lock_common kernel/locking/mutex.c:968 [inline]
       __mutex_lock+0x13d/0x10b0 kernel/locking/mutex.c:1109
       rfkill_register+0x36/0xa10 net/rfkill/core.c:1016
       hci_register_dev+0x42e/0xc00 net/bluetooth/hci_core.c:3773
       __vhci_create_device+0x2c8/0x5c0 drivers/bluetooth/hci_vhci.c:129
       vhci_create_device drivers/bluetooth/hci_vhci.c:153 [inline]
       vhci_open_timeout+0x38/0x50 drivers/bluetooth/hci_vhci.c:310
       process_one_work+0x9a9/0x14b0 kernel/workqueue.c:2282
       worker_thread+0x61d/0x1310 kernel/workqueue.c:2428
       kthread+0x38f/0x470 kernel/kthread.c:313
       ret_from_fork+0x22/0x30 arch/x86/entry/entry_64.S:299

-> #1 (&data->open_mutex){+.+.}-{3:3}:
       __mutex_lock_common kernel/locking/mutex.c:968 [inline]
       __mutex_lock+0x13d/0x10b0 kernel/locking/mutex.c:1109
       vhci_send_frame+0x63/0xa0 drivers/bluetooth/hci_vhci.c:71
       hci_send_frame+0x1b9/0x320 net/bluetooth/hci_core.c:4060
       hci_sched_acl_pkt net/bluetooth/hci_core.c:4585 [inline]
       hci_sched_acl net/bluetooth/hci_core.c:4670 [inline]
       hci_tx_work+0x10af/0x1660 net/bluetooth/hci_core.c:4741
       process_one_work+0x9a9/0x14b0 kernel/workqueue.c:2282
       worker_thread+0x61d/0x1310 kernel/workqueue.c:2428
       kthread+0x38f/0x470 kernel/kthread.c:313
       ret_from_fork+0x22/0x30 arch/x86/entry/entry_64.S:299

-> #0 ((work_completion)(&hdev->tx_work)){+.+.}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:2988 [inline]
       check_prevs_add kernel/locking/lockdep.c:3113 [inline]
       validate_chain kernel/locking/lockdep.c:3729 [inline]
       __lock_acquire+0x29e7/0x5b00 kernel/locking/lockdep.c:4955
       lock_acquire kernel/locking/lockdep.c:5566 [inline]
       lock_acquire+0x197/0x470 kernel/locking/lockdep.c:5531
       __flush_work+0x105/0xa90 kernel/workqueue.c:3053
       hci_dev_do_close+0x131/0x1240 net/bluetooth/hci_core.c:1745
       hci_rfkill_set_block+0x166/0x1a0 net/bluetooth/hci_core.c:2223
       rfkill_set_block+0x1fd/0x540 net/rfkill/core.c:341
       rfkill_fop_write+0x253/0x4b0 net/rfkill/core.c:1240
       vfs_write+0x29a/0xa70 fs/read_write.c:603
       ksys_write+0x1f6/0x260 fs/read_write.c:658
       do_syscall_64+0x33/0x40 arch/x86/entry/common.c:46
       entry_SYSCALL_64_after_hwframe+0x62/0xc7

other info that might help us debug this:

Chain exists of:
  (work_completion)(&hdev->tx_work) --> rfkill_global_mutex --> &hdev->req_lock

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&hdev->req_lock);
                               lock(rfkill_global_mutex);
                               lock(&hdev->req_lock);
  lock((work_completion)(&hdev->tx_work));

 *** DEADLOCK ***

2 locks held by syz-executor.1/6446:
 #0: ffffffff85619668 (rfkill_global_mutex){+.+.}-{3:3}, at: rfkill_fop_write+0xff/0x4b0 net/rfkill/core.c:1232
 #1: ffff888018018f40 (&hdev->req_lock){+.+.}-{3:3}, at: hci_dev_do_close+0xef/0x1240 net/bluetooth/hci_core.c:1734

stack backtrace:
CPU: 1 PID: 6446 Comm: syz-executor.1 Not tainted 5.10.209 #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x107/0x167 lib/dump_stack.c:118
 check_noncircular+0x263/0x2e0 kernel/locking/lockdep.c:2123
 check_prev_add kernel/locking/lockdep.c:2988 [inline]
 check_prevs_add kernel/locking/lockdep.c:3113 [inline]
 validate_chain kernel/locking/lockdep.c:3729 [inline]
 __lock_acquire+0x29e7/0x5b00 kernel/locking/lockdep.c:4955
 lock_acquire kernel/locking/lockdep.c:5566 [inline]
 lock_acquire+0x197/0x470 kernel/locking/lockdep.c:5531
 __flush_work+0x105/0xa90 kernel/workqueue.c:3053
 hci_dev_do_close+0x131/0x1240 net/bluetooth/hci_core.c:1745
 hci_rfkill_set_block+0x166/0x1a0 net/bluetooth/hci_core.c:2223
 rfkill_set_block+0x1fd/0x540 net/rfkill/core.c:341
 rfkill_fop_write+0x253/0x4b0 net/rfkill/core.c:1240
 vfs_write+0x29a/0xa70 fs/read_write.c:603
 ksys_write+0x1f6/0x260 fs/read_write.c:658
 do_syscall_64+0x33/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x62/0xc7
RIP: 0033:0x7f75fb3fbb19
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f75f8971188 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f75fb50ef60 RCX: 00007f75fb3fbb19
RDX: 0000000000000008 RSI: 00000000200000c0 RDI: 0000000000000003
RBP: 00007f75fb455f6d R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffea49cbc1f R14: 00007f75f8971300 R15: 0000000000022000
FAULT_INJECTION: forcing a failure.
name failslab, interval 1, probability 0, space 0, times 0
CPU: 0 PID: 6453 Comm: syz-executor.6 Not tainted 5.10.209 #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x107/0x167 lib/dump_stack.c:118
 fail_dump lib/fault-inject.c:52 [inline]
 should_fail.cold+0x5/0xa lib/fault-inject.c:146
 should_failslab+0x5/0x20 mm/slab_common.c:1193
 slab_pre_alloc_hook mm/slab.h:515 [inline]
 slab_alloc_node mm/slub.c:2821 [inline]
 kmem_cache_alloc_node+0x55/0x330 mm/slub.c:2932
 __alloc_skb+0x6d/0x5b0 net/core/skbuff.c:198
 alloc_skb include/linux/skbuff.h:1102 [inline]
 nlmsg_new include/net/netlink.h:953 [inline]
 audit_buffer_alloc kernel/audit.c:1782 [inline]
 audit_log_start.part.0+0x2a3/0x730 kernel/audit.c:1900
 audit_log_start+0x5f/0x90 kernel/audit.c:1856
 audit_seccomp+0x5d/0x200 kernel/auditsc.c:2722
 seccomp_log kernel/seccomp.c:770 [inline]
 __seccomp_filter+0x62b/0x1470 kernel/seccomp.c:1012
 __secure_computing+0xac/0x290 kernel/seccomp.c:1077
 syscall_trace_enter.constprop.0+0x84/0x1e0 kernel/entry/common.c:58
 do_syscall_64+0xf/0x40 arch/x86/entry/common.c:41
 entry_SYSCALL_64_after_hwframe+0x62/0xc7
RIP: 0033:0x7f4ab43e869c
Code: ec 28 48 89 54 24 18 48 89 74 24 10 89 7c 24 08 e8 f9 fc ff ff 48 8b 54 24 18 48 8b 74 24 10 41 89 c0 8b 7c 24 08 31 c0 0f 05 <48> 3d 00 f0 ff ff 77 34 44 89 c7 48 89 44 24 08 e8 2f fd ff ff 48
RSP: 002b:00007f4ab19ab170 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f4ab43e869c
RDX: 000000000000000f RSI: 00007f4ab19ab1e0 RDI: 0000000000000003
RBP: 00007f4ab19ab1d0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000002
R13: 00007ffdc478285f R14: 00007f4ab19ab300 R15: 0000000000022000