------------[ cut here ]------------
workqueue: cannot queue hci_cmd_timeout on wq hci0
WARNING: kernel/workqueue.c:2251 at __queue_work+0xcbb/0x10f0 kernel/workqueue.c:2250, CPU#3: kworker/u32:18/7663
Modules linked in:
CPU: 3 UID: 0 PID: 7663 Comm: kworker/u32:18 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Workqueue: netns cleanup_net
RIP: 0010:__queue_work+0xcbf/0x10f0 kernel/workqueue.c:2250
Code: 00 00 00 fc ff df 49 8d 94 24 78 01 00 00 48 89 f9 48 c1 e9 03 80 3c 01 00 0f 85 15 04 00 00 48 8d 3d 05 aa ec 0e 48 8b 75 18 <67> 48 0f b9 3a e9 77 f7 ff ff e8 62 8e 38 00 90 0f 0b 90 e9 ff f5
RSP: 0000:ffffc900005e8bf0 EFLAGS: 00010046
RAX: dffffc0000000000 RBX: 0000000000000100 RCX: 1ffff1100edf5151
RDX: ffff888025c02978 RSI: ffffffff8a6b5a10 RDI: ffffffff90ba6650
RBP: ffff888076fa8a70 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000100 R11: 0000000000000000 R12: ffff888025c02800
R13: 1ffff920000bd18f R14: ffffffff81cdcd50 R15: 0000000000000001
FS:  0000000000000000(0000) GS:ffff8880976e3000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000800ff000 CR3: 0000000028a59000 CR4: 0000000000352ef0
Call Trace:
 <IRQ>
 call_timer_fn+0x19a/0x590 kernel/time/timer.c:1748
 expire_timers kernel/time/timer.c:1794 [inline]
 __run_timers+0x570/0xac0 kernel/time/timer.c:2373
 __run_timer_base kernel/time/timer.c:2385 [inline]
 __run_timer_base kernel/time/timer.c:2377 [inline]
 run_timer_base+0x114/0x190 kernel/time/timer.c:2394
 run_timer_softirq+0x1a/0x50 kernel/time/timer.c:2404
 handle_softirqs+0x1ea/0x910 kernel/softirq.c:622
 __do_softirq kernel/softirq.c:656 [inline]
 invoke_softirq kernel/softirq.c:496 [inline]
 __irq_exit_rcu+0xef/0x150 kernel/softirq.c:723
 irq_exit_rcu+0x9/0x30 kernel/softirq.c:739
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1056 [inline]
 sysvec_apic_timer_interrupt+0xa3/0xc0 arch/x86/kernel/apic/apic.c:1056
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:lockdep_unregister_key+0x12b/0x1d0 kernel/locking/lockdep.c:6616
Code: e8 da dd ff ff 48 83 2d 9a 6e 21 14 01 89 c3 e8 2b e0 ff ff 9c 58 f6 c4 02 0f 85 8a 00 00 00 f7 c5 00 02 00 00 74 01 fb 84 db <75> 40 5b 5d 41 5c e9 4a be 09 00 9c 58 f6 c4 02 0f 84 16 ff ff ff
RSP: 0000:ffffc9000416f728 EFLAGS: 00000246
RAX: 0000000000000046 RBX: 0000000000000000 RCX: 0000000000000001
RDX: 0000000000000000 RSI: ffffffff8dd32240 RDI: ffffffff8bfa3320
RBP: 0000000000000246 R08: 0000000000050602 R09: ffffffff960db6e4
R10: 0000000000000200 R11: 0000000000000000 R12: ffffffff9768ab38
R13: ffff888060fa4000 R14: ffff888060fa44c8 R15: 0000000000000002
 __qdisc_destroy+0x11a/0x490 net/sched/sch_generic.c:1079
 qdisc_put+0xb0/0xf0 net/sched/sch_generic.c:1105
 shutdown_scheduler_queue+0xa5/0x160 net/sched/sch_generic.c:1158
 netdev_for_each_tx_queue include/linux/netdevice.h:2680 [inline]
 dev_shutdown+0xb3/0x440 net/sched/sch_generic.c:1490
 unregister_netdevice_many_notify+0xd56/0x2580 net/core/dev.c:12384
 unregister_netdevice_many net/core/dev.c:12459 [inline]
 default_device_exit_batch+0x946/0xc60 net/core/dev.c:13051
 ops_exit_list net/core/net_namespace.c:205 [inline]
 ops_undo_list+0x363/0xab0 net/core/net_namespace.c:252
 cleanup_net+0x419/0x830 net/core/net_namespace.c:696
 process_one_work+0x9c2/0x1840 kernel/workqueue.c:3257
 process_scheduled_works kernel/workqueue.c:3340 [inline]
 worker_thread+0x5da/0xe40 kernel/workqueue.c:3421
 kthread+0x3b3/0x730 kernel/kthread.c:463
 ret_from_fork+0x754/0xaf0 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
 </TASK>
----------------
Code disassembly (best guess):
   0:	00 00                	add    %al,(%rax)
   2:	00 fc                	add    %bh,%ah
   4:	ff                   	lcall  (bad)
   5:	df 49 8d             	fisttps -0x73(%rcx)
   8:	94                   	xchg   %eax,%esp
   9:	24 78                	and    $0x78,%al
   b:	01 00                	add    %eax,(%rax)
   d:	00 48 89             	add    %cl,-0x77(%rax)
  10:	f9                   	stc
  11:	48 c1 e9 03          	shr    $0x3,%rcx
  15:	80 3c 01 00          	cmpb   $0x0,(%rcx,%rax,1)
  19:	0f 85 15 04 00 00    	jne    0x434
  1f:	48 8d 3d 05 aa ec 0e 	lea    0xeecaa05(%rip),%rdi        # 0xeecaa2b
  26:	48 8b 75 18          	mov    0x18(%rbp),%rsi
* 2a:	67 48 0f b9 3a       	ud1    (%edx),%rdi <-- trapping instruction
  2f:	e9 77 f7 ff ff       	jmp    0xfffff7ab
  34:	e8 62 8e 38 00       	call   0x388e9b
  39:	90                   	nop
  3a:	0f 0b                	ud2
  3c:	90                   	nop
  3d:	e9                   	.byte 0xe9
  3e:	ff f5                	push   %rbp