======================================
| [  200.010664] br2: port 1(vethhv-21) entered disabled state
| [  200.039742] ------------[ cut here ]------------
| [  200.040477] WARNING: CPU: 2 PID: 11 at net/core/dev.c:11120 unregister_netdevice_many_notify (net/core/dev.c:11120 (discriminator 1)) 
| [  200.041855] Modules linked in: vxlan ip6_udp_tunnel udp_tunnel nft_chain_nat xt_nat nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 nft_compat nf_tables libcrc32c
[  200.044803] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014
[  200.046251] Workqueue: netns cleanup_net
[  200.046790] RIP: 0010:unregister_netdevice_many_notify (net/core/dev.c:11120 (discriminator 1)) 
[ 200.047563] Code: 05 31 4a 09 01 01 90 ba 32 1b 00 00 48 c7 c6 09 ec 6e ab 48 c7 c7 00 3a 72 ab e8 2f 9a 55 ff 90 0f 0b 90 90 e9 15 fc ff ff 90 <0f> 0b 90 e9 23 fc ff ff e8 17 35 2e 00 0f 1f 80 00 00 00 00 90 90
All code
========
   0:	05 31 4a 09 01       	add    $0x1094a31,%eax
   5:	01 90 ba 32 1b 00    	add    %edx,0x1b32ba(%rax)
   b:	00 48 c7             	add    %cl,-0x39(%rax)
   e:	c6                   	(bad)
   f:	09 ec                	or     %ebp,%esp
  11:	6e                   	outsb  %ds:(%rsi),(%dx)
  12:	ab                   	stos   %eax,%es:(%rdi)
  13:	48 c7 c7 00 3a 72 ab 	mov    $0xffffffffab723a00,%rdi
  1a:	e8 2f 9a 55 ff       	call   0xffffffffff559a4e
  1f:	90                   	nop
  20:	0f 0b                	ud2
  22:	90                   	nop
  23:	90                   	nop
  24:	e9 15 fc ff ff       	jmp    0xfffffffffffffc3e
  29:	90                   	nop
  2a:*	0f 0b                	ud2		<-- trapping instruction
  2c:	90                   	nop
  2d:	e9 23 fc ff ff       	jmp    0xfffffffffffffc55
  32:	e8 17 35 2e 00       	call   0x2e354e
  37:	0f 1f 80 00 00 00 00 	nopl   0x0(%rax)
  3e:	90                   	nop
  3f:	90                   	nop

Code starting with the faulting instruction
===========================================
   0:	0f 0b                	ud2
   2:	90                   	nop
   3:	e9 23 fc ff ff       	jmp    0xfffffffffffffc2b
   8:	e8 17 35 2e 00       	call   0x2e3524
   d:	0f 1f 80 00 00 00 00 	nopl   0x0(%rax)
  14:	90                   	nop
  15:	90                   	nop
[  200.049304] RSP: 0018:ffffa04f40063d78 EFLAGS: 00010202
[  200.049691] RAX: ffff8e3682a101c0 RBX: ffffa04f40063e08 RCX: 0000000000000000
[  200.050215] RDX: ffff8e3684bfaf18 RSI: 0000000000000000 RDI: ffffffffabc4aa80
[  200.050738] RBP: ffff8e3682a10000 R08: 0000000000000001 R09: 0000000000000001
[  200.051268] R10: 0000000000000004 R11: 0000000000000001 R12: ffff8e36827df600
[  200.051805] R13: ffff8e3684bfa9c0 R14: dead000000000100 R15: ffff8e3684bfa9c0
[  200.052367] FS:  0000000000000000(0000) GS:ffff8e36bed00000(0000) knlGS:0000000000000000
[  200.052986] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  200.053428] CR2: 00007f36ad3e5000 CR3: 0000000010860002 CR4: 0000000000770ef0
[  200.053980] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[  200.054523] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[  200.055071] PKRU: 55555554
[  200.055305] Call Trace:
[  200.055517]  <TASK>
[  200.055699] ? __warn (kernel/panic.c:677) 
[  200.055971] ? unregister_netdevice_many_notify (net/core/dev.c:11120 (discriminator 1)) 
[  200.056401] ? report_bug (lib/bug.c:201 lib/bug.c:219) 
[  200.056702] ? handle_bug (arch/x86/kernel/traps.c:238) 
[  200.056993] ? exc_invalid_op (arch/x86/kernel/traps.c:259 (discriminator 1)) 
[  200.057299] ? asm_exc_invalid_op (./arch/x86/include/asm/idtentry.h:568) 
[  200.057632] ? unregister_netdevice_many_notify (net/core/dev.c:11120 (discriminator 1)) 
[  200.058069] ? unregister_netdevice_many_notify (net/core/dev.c:6962 net/core/dev.c:11120) 
[  200.058513] cleanup_net (net/core/net_namespace.c:633) 
[  200.058812] ? process_one_work (kernel/workqueue.c:2606) 
[  200.059148] process_one_work (kernel/workqueue.c:2633) 
[  200.059462] worker_thread (kernel/workqueue.c:2700 kernel/workqueue.c:2787) 
[  200.059771] ? __pfx_worker_thread (kernel/workqueue.c:2733) 
[  200.060119] kthread (kernel/kthread.c:388) 
[  200.060375] ? __pfx_kthread (kernel/kthread.c:341) 
[  200.060682] ret_from_fork (arch/x86/kernel/process.c:147) 
[  200.060974] ? __pfx_kthread (kernel/kthread.c:341) 
[  200.061275] ret_from_fork_asm (arch/x86/entry/entry_64.S:250) 
| [  200.064700] ---[ end trace 0000000000000000 ]---
| [  200.065734] ------------[ cut here ]------------
| [  200.066301] WARNING: CPU: 2 PID: 11 at net/core/dev.c:11120 unregister_netdevice_many_notify (net/core/dev.c:11120 (discriminator 1)) 
| [  200.067081] Modules linked in: vxlan ip6_udp_tunnel udp_tunnel nft_chain_nat xt_nat nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 nft_compat nf_tables libcrc32c
[  200.070231] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014
[  200.072019] Workqueue: netns cleanup_net
[  200.072647] RIP: 0010:unregister_netdevice_many_notify (net/core/dev.c:11120 (discriminator 1)) 
[ 200.073641] Code: 05 31 4a 09 01 01 90 ba 32 1b 00 00 48 c7 c6 09 ec 6e ab 48 c7 c7 00 3a 72 ab e8 2f 9a 55 ff 90 0f 0b 90 90 e9 15 fc ff ff 90 <0f> 0b 90 e9 23 fc ff ff e8 17 35 2e 00 0f 1f 80 00 00 00 00 90 90
All code
========
   0:	05 31 4a 09 01       	add    $0x1094a31,%eax
   5:	01 90 ba 32 1b 00    	add    %edx,0x1b32ba(%rax)
   b:	00 48 c7             	add    %cl,-0x39(%rax)
   e:	c6                   	(bad)
   f:	09 ec                	or     %ebp,%esp
  11:	6e                   	outsb  %ds:(%rsi),(%dx)
  12:	ab                   	stos   %eax,%es:(%rdi)
  13:	48 c7 c7 00 3a 72 ab 	mov    $0xffffffffab723a00,%rdi
  1a:	e8 2f 9a 55 ff       	call   0xffffffffff559a4e
  1f:	90                   	nop
  20:	0f 0b                	ud2
  22:	90                   	nop
  23:	90                   	nop
  24:	e9 15 fc ff ff       	jmp    0xfffffffffffffc3e
  29:	90                   	nop
  2a:*	0f 0b                	ud2		<-- trapping instruction
  2c:	90                   	nop
  2d:	e9 23 fc ff ff       	jmp    0xfffffffffffffc55
  32:	e8 17 35 2e 00       	call   0x2e354e
  37:	0f 1f 80 00 00 00 00 	nopl   0x0(%rax)
  3e:	90                   	nop
  3f:	90                   	nop

Code starting with the faulting instruction
===========================================
   0:	0f 0b                	ud2
   2:	90                   	nop
   3:	e9 23 fc ff ff       	jmp    0xfffffffffffffc2b
   8:	e8 17 35 2e 00       	call   0x2e3524
   d:	0f 1f 80 00 00 00 00 	nopl   0x0(%rax)
  14:	90                   	nop
  15:	90                   	nop
[  200.076297] RSP: 0018:ffffa04f40063d78 EFLAGS: 00010287
[  200.077194] RAX: ffff8e36827b81c0 RBX: ffffa04f40063e08 RCX: 0000000000000000
[  200.078164] RDX: ffff8e36826d4098 RSI: 0000000000000000 RDI: ffffffffabc4aa80
[  200.078700] RBP: ffff8e36827b8000 R08: 0000000000000001 R09: 0000000000000001
[  200.079317] R10: 0000000000000004 R11: 0000000000000001 R12: ffff8e36827df600
[  200.079958] R13: ffff8e36826d40c0 R14: dead000000000100 R15: ffff8e36826d40c0
[  200.080776] FS:  0000000000000000(0000) GS:ffff8e36bed00000(0000) knlGS:0000000000000000
[  200.081983] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  200.082935] CR2: 00007f36ad3e5000 CR3: 0000000010860002 CR4: 0000000000770ef0
[  200.084155] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[  200.085419] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[  200.086595] PKRU: 55555554
[  200.087058] Call Trace:
[  200.087492]  <TASK>
[  200.087856] ? __warn (kernel/panic.c:677) 
[  200.088306] ? unregister_netdevice_many_notify (net/core/dev.c:11120 (discriminator 1)) 
[  200.089196] ? report_bug (lib/bug.c:201 lib/bug.c:219) 
[  200.089772] ? handle_bug (arch/x86/kernel/traps.c:238) 
[  200.090280] ? exc_invalid_op (arch/x86/kernel/traps.c:259 (discriminator 1)) 
[  200.090838] ? asm_exc_invalid_op (./arch/x86/include/asm/idtentry.h:568) 
[  200.091453] ? unregister_netdevice_many_notify (net/core/dev.c:11120 (discriminator 1)) 
[  200.092080] ? unregister_netdevice_many_notify (net/core/dev.c:6962 net/core/dev.c:11120) 
[  200.092549] cleanup_net (net/core/net_namespace.c:633) 
[  200.092977] ? process_one_work (kernel/workqueue.c:2606) 
[  200.093310] process_one_work (kernel/workqueue.c:2633) 
[  200.093768] worker_thread (kernel/workqueue.c:2700 kernel/workqueue.c:2787) 
[  200.094133] ? __pfx_worker_thread (kernel/workqueue.c:2733) 
[  200.094606] kthread (kernel/kthread.c:388) 
[  200.094855] ? __pfx_kthread (kernel/kthread.c:341) 
[  200.095172] ret_from_fork (arch/x86/kernel/process.c:147) 
[  200.095560] ? __pfx_kthread (kernel/kthread.c:341) 


Finger prints:
unregister_netdevice_many_notify:cleanup_net:process_one_work:worker_thread
unregister_netdevice_many_notify:cleanup_net:process_one_work:worker_thread