======================================
| [  124.275284][   T66] ------------[ cut here ]------------
| [  124.275651][   T66] RTNL: assertion failed at net/core/link_watch.c (59)
| [ 124.275930][ T66] WARNING: CPU: 2 PID: 66 at net/core/link_watch.c:59 default_operstate (net/core/link_watch.c:59 (discriminator 3))
| [  124.276275][   T66] Modules linked in: dccp_ipv6 dccp_ipv4 dccp act_gact cls_flower sch_ingress vxlan sch_etf sch_fq [last unloaded: test_blackhole_dev]
[  124.277140][   T66] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[  124.277405][   T66] Workqueue: netns cleanup_net
[ 124.277621][ T66] RIP: 0010:default_operstate (net/core/link_watch.c:59 (discriminator 3))
[ 124.277841][ T66] Code: 83 e4 01 0f 85 03 ff ff ff c6 05 08 23 5c 02 01 90 ba 3b 00 00 00 48 c7 c6 00 7c 17 97 48 c7 c7 40 7c 17 97 e8 b3 b2 e5 fd 90 <0f> 0b 90 90 e9 d9 fe ff ff 48 89 ef e8 81 63 6d fe e9 f7 fd ff ff
All code
========
   0:	83 e4 01             	and    $0x1,%esp
   3:	0f 85 03 ff ff ff    	jne    0xffffffffffffff0c
   9:	c6 05 08 23 5c 02 01 	movb   $0x1,0x25c2308(%rip)        # 0x25c2318
  10:	90                   	nop
  11:	ba 3b 00 00 00       	mov    $0x3b,%edx
  16:	48 c7 c6 00 7c 17 97 	mov    $0xffffffff97177c00,%rsi
  1d:	48 c7 c7 40 7c 17 97 	mov    $0xffffffff97177c40,%rdi
  24:	e8 b3 b2 e5 fd       	call   0xfffffffffde5b2dc
  29:	90                   	nop
  2a:*	0f 0b                	ud2		<-- trapping instruction
  2c:	90                   	nop
  2d:	90                   	nop
  2e:	e9 d9 fe ff ff       	jmp    0xffffffffffffff0c
  33:	48 89 ef             	mov    %rbp,%rdi
  36:	e8 81 63 6d fe       	call   0xfffffffffe6d63bc
  3b:	e9 f7 fd ff ff       	jmp    0xfffffffffffffe37

Code starting with the faulting instruction
===========================================
   0:	0f 0b                	ud2
   2:	90                   	nop
   3:	90                   	nop
   4:	e9 d9 fe ff ff       	jmp    0xfffffffffffffee2
   9:	48 89 ef             	mov    %rbp,%rdi
   c:	e8 81 63 6d fe       	call   0xfffffffffe6d6392
  11:	e9 f7 fd ff ff       	jmp    0xfffffffffffffe0d
[  124.278492][   T66] RSP: 0018:ffffc90000477a48 EFLAGS: 00010282
[  124.278738][   T66] RAX: 0000000000000000 RBX: ffff88800bb44000 RCX: 1ffffffff2f3dd8c
[  124.279041][   T66] RDX: 0000000000000000 RSI: 0000000000000004 RDI: 0000000000000001
[  124.279351][   T66] RBP: 0000000000000000 R08: 0000000000000000 R09: fffffbfff2f3dd8c
[  124.279636][   T66] R10: 0000000000000003 R11: ffff888008b6c5c0 R12: 0000000000000000
[  124.279920][   T66] R13: dffffc0000000000 R14: ffff88800bb41000 R15: ffff88800bb445c0
[  124.280214][   T66] FS:  0000000000000000(0000) GS:ffff88806d100000(0000) knlGS:0000000000000000
[  124.280570][   T66] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  124.280811][   T66] CR2: 00007fc94ec4c2c0 CR3: 000000002293a003 CR4: 0000000000772ef0
[  124.281128][   T66] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[  124.281422][   T66] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[  124.281836][   T66] PKRU: 55555554
[  124.282008][   T66] Call Trace:
[  124.282163][   T66]  <TASK>
[ 124.282273][ T66] ? default_operstate (net/core/link_watch.c:59 (discriminator 3))
[ 124.282491][ T66] ? __warn (kernel/panic.c:748)
[ 124.282650][ T66] ? default_operstate (net/core/link_watch.c:59 (discriminator 3))
[ 124.282845][ T66] ? report_bug (lib/bug.c:201 lib/bug.c:219)
[ 124.283055][ T66] ? handle_bug (arch/x86/kernel/traps.c:285)
[ 124.283219][ T66] ? exc_invalid_op (arch/x86/kernel/traps.c:309 (discriminator 1))
[ 124.283429][ T66] ? asm_exc_invalid_op (./arch/x86/include/asm/idtentry.h:621)
[ 124.283626][ T66] ? default_operstate (net/core/link_watch.c:59 (discriminator 3))
[ 124.283820][ T66] ? default_operstate (net/core/link_watch.c:59 (discriminator 3))
[ 124.284009][ T66] rfc2863_policy (net/core/link_watch.c:78)
[ 124.284209][ T66] linkwatch_do_dev (net/core/link_watch.c:180)
[ 124.284424][ T66] netdev_run_todo (net/core/dev.c:10894 (discriminator 2))
[ 124.284630][ T66] ? __pfx_netdev_run_todo (net/core/dev.c:10867)
[ 124.284824][ T66] ? __pfx_unregister_netdevice_queue (net/core/dev.c:11455)
[ 124.285072][ T66] default_device_exit_batch (net/core/dev.c:12051)
[ 124.285267][ T66] ? __pfx_default_device_exit_batch (net/core/dev.c:12051)
[ 124.285538][ T66] ? ops_exit_list (net/core/net_namespace.c:171 (discriminator 3))
[ 124.285741][ T66] cleanup_net (net/core/net_namespace.c:647 (discriminator 3))
[ 124.285949][ T66] ? __pfx_lock_acquire.part.0 (kernel/locking/lockdep.c:5814)
[ 124.286163][ T66] ? __pfx_cleanup_net (net/core/net_namespace.c:592)
[ 124.286370][ T66] ? trace_lock_acquire (./include/trace/events/lock.h:24 (discriminator 37))
[ 124.286572][ T66] ? lock_acquire (kernel/locking/lockdep.c:5822)
[ 124.286765][ T66] ? process_one_work (kernel/workqueue.c:3205)
[ 124.286967][ T66] process_one_work (kernel/workqueue.c:3229)
[ 124.287176][ T66] ? __pfx___lock_release (kernel/locking/lockdep.c:5501)
[ 124.287394][ T66] ? __pfx_process_one_work (kernel/workqueue.c:3131)
[ 124.287596][ T66] ? assign_work (kernel/workqueue.c:1200)
[ 124.287789][ T66] worker_thread (kernel/workqueue.c:3304 kernel/workqueue.c:3391)
[ 124.287993][ T66] ? lockdep_hardirqs_on_prepare (kernel/locking/lockdep.c:4347 kernel/locking/lockdep.c:4406)
[ 124.288235][ T66] ? __pfx_worker_thread (kernel/workqueue.c:3337)
[ 124.288440][ T66] ? __pfx_worker_thread (kernel/workqueue.c:3337)
[ 124.288632][ T66] kthread (kernel/kthread.c:389)
[ 124.288783][ T66] ? __pfx_kthread (kernel/kthread.c:342)
[ 124.288982][ T66] ret_from_fork (arch/x86/kernel/process.c:147)
[ 124.289172][ T66] ? __pfx_kthread (kernel/kthread.c:342)


Finger prints:
default_operstate:rfc2863_policy:linkwatch_do_dev:netdev_run_todo:default_device_exit_batch