======================================
| [  250.799909][   T66] ------------[ cut here ]------------
| [  250.800419][   T66] RTNL: assertion failed at net/core/link_watch.c (59)
| [ 250.800869][ T66] WARNING: CPU: 1 PID: 66 at net/core/link_watch.c:59 default_operstate (net/core/link_watch.c:59 (discriminator 3))
| [  250.801314][   T66] Modules linked in: veth
[  250.801984][   T66] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[  250.802277][   T66] Workqueue: netns cleanup_net
[ 250.802944][ T66] RIP: 0010:default_operstate (net/core/link_watch.c:59 (discriminator 3))
[ 250.803357][ T66] Code: 83 e4 01 0f 85 03 ff ff ff c6 05 17 5d 39 02 01 90 ba 3b 00 00 00 48 c7 c6 60 11 f7 8c 48 c7 c7 a0 11 f7 8c e8 43 00 eb fd 90 <0f> 0b 90 90 e9 d9 fe ff ff 48 89 ef e8 21 27 72 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 17 5d 39 02 01 	movb   $0x1,0x2395d17(%rip)        # 0x2395d27
  10:	90                   	nop
  11:	ba 3b 00 00 00       	mov    $0x3b,%edx
  16:	48 c7 c6 60 11 f7 8c 	mov    $0xffffffff8cf71160,%rsi
  1d:	48 c7 c7 a0 11 f7 8c 	mov    $0xffffffff8cf711a0,%rdi
  24:	e8 43 00 eb fd       	call   0xfffffffffdeb006c
  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 21 27 72 fe       	call   0xfffffffffe72275c
  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 21 27 72 fe       	call   0xfffffffffe722732
  11:	e9 f7 fd ff ff       	jmp    0xfffffffffffffe0d
[  250.804276][   T66] RSP: 0018:ffffc90000477a48 EFLAGS: 00010282
[  250.804712][   T66] RAX: 0000000000000000 RBX: ffff888002171000 RCX: 1ffffffff1afb58c
[  250.805136][   T66] RDX: 0000000000000000 RSI: 0000000000000004 RDI: 0000000000000001
[  250.805685][   T66] RBP: 0000000000000000 R08: 0000000000000000 R09: fffffbfff1afb58c
[  250.806137][   T66] R10: 0000000000000003 R11: ffff8880084845c0 R12: 0000000000000000
[  250.806573][   T66] R13: dffffc0000000000 R14: ffff8880082b9000 R15: ffff888002171598
[  250.807037][   T66] FS:  0000000000000000(0000) GS:ffff888036080000(0000) knlGS:0000000000000000
[  250.807542][   T66] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  250.807872][   T66] CR2: 00007f5384007028 CR3: 0000000027726006 CR4: 0000000000772ef0
[  250.808315][   T66] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[  250.809093][   T66] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[  250.809792][   T66] PKRU: 55555554
[  250.810102][   T66] Call Trace:
[  250.810323][   T66]  <TASK>
[ 250.810433][ T66] ? default_operstate (net/core/link_watch.c:59 (discriminator 3))
[ 250.810681][ T66] ? __warn (kernel/panic.c:748)
[ 250.810873][ T66] ? default_operstate (net/core/link_watch.c:59 (discriminator 3))
[ 250.811106][ T66] ? report_bug (lib/bug.c:201 lib/bug.c:219)
[ 250.811393][ T66] ? handle_bug (arch/x86/kernel/traps.c:285)
[ 250.811597][ T66] ? exc_invalid_op (arch/x86/kernel/traps.c:309 (discriminator 1))
[ 250.811943][ T66] ? asm_exc_invalid_op (./arch/x86/include/asm/idtentry.h:621)
[ 250.812409][ T66] ? default_operstate (net/core/link_watch.c:59 (discriminator 3))
[ 250.812815][ T66] ? default_operstate (net/core/link_watch.c:59 (discriminator 3))
[ 250.813275][ T66] rfc2863_policy (net/core/link_watch.c:78)
[ 250.813724][ T66] linkwatch_do_dev (net/core/link_watch.c:180)
[ 250.814082][ T66] netdev_run_todo (net/core/dev.c:10894 (discriminator 2))
[ 250.814388][ T66] ? __pfx_netdev_run_todo (net/core/dev.c:10867)
[ 250.814639][ T66] ? vrf_dellink (drivers/net/vrf.c:1668)
[ 250.814896][ T66] ? __pfx_unregister_netdevice_queue (net/core/dev.c:11455)
[ 250.815223][ T66] default_device_exit_batch (net/core/dev.c:12051)
[ 250.815522][ T66] ? __pfx_default_device_exit_batch (net/core/dev.c:12051)
[ 250.815879][ T66] ? mutex_is_locked (./arch/x86/include/asm/atomic64_64.h:15 ./include/linux/atomic/atomic-arch-fallback.h:2583 ./include/linux/atomic/atomic-long.h:38 ./include/linux/atomic/atomic-instrumented.h:3189 kernel/locking/mutex.h:47 kernel/locking/mutex.c:66)
[ 250.816227][ T66] ? nexthop_net_exit_batch_rtnl (net/ipv4/nexthop.c:585 net/ipv4/nexthop.c:2158 net/ipv4/nexthop.c:2666 net/ipv4/nexthop.c:4010)
[ 250.816471][ T66] cleanup_net (net/core/net_namespace.c:647 (discriminator 3))
[ 250.816651][ T66] ? __pfx_lock_acquire.part.0 (kernel/locking/lockdep.c:5814)
[ 250.816825][ T66] ? __pfx_cleanup_net (net/core/net_namespace.c:592)
[ 250.816994][ T66] ? trace_lock_acquire (./include/trace/events/lock.h:24 (discriminator 37))
[ 250.817196][ T66] ? lock_acquire (kernel/locking/lockdep.c:5822)
[ 250.817364][ T66] ? process_one_work (kernel/workqueue.c:3205)
[ 250.817546][ T66] process_one_work (kernel/workqueue.c:3229)
[ 250.817729][ T66] ? __pfx___lock_release (kernel/locking/lockdep.c:5501)
[ 250.817901][ T66] ? __pfx_process_one_work (kernel/workqueue.c:3131)
[ 250.818068][ T66] ? assign_work (kernel/workqueue.c:1200)
[ 250.818324][ T66] worker_thread (kernel/workqueue.c:3304 kernel/workqueue.c:3391)
[ 250.818589][ T66] ? lockdep_hardirqs_on_prepare (kernel/locking/lockdep.c:4347 kernel/locking/lockdep.c:4406)
[ 250.818872][ T66] ? __pfx_worker_thread (kernel/workqueue.c:3337)
[ 250.819088][ T66] ? __pfx_worker_thread (kernel/workqueue.c:3337)
[ 250.819348][ T66] kthread (kernel/kthread.c:389)
[ 250.819539][ T66] ? __pfx_kthread (kernel/kthread.c:342)
[ 250.819777][ T66] ret_from_fork (arch/x86/kernel/process.c:147)
[ 250.819988][ T66] ? __pfx_kthread (kernel/kthread.c:342)


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