======================================
| [   62.041385][   T11] br2: port 1(vethhv-21) entered disabled state
| [   62.087747][   T11] ------------[ cut here ]------------
| [ 62.088098][ T11] WARNING: CPU: 1 PID: 11 at net/core/dev.c:11120 unregister_netdevice_many_notify (net/core/dev.c:11120 (discriminator 1)) 
| [   62.089417][   T11] Modules linked in: vxlan ip6_udp_tunnel udp_tunnel
[   62.090268][   T11] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014
[   62.090895][   T11] Workqueue: netns cleanup_net
[ 62.091154][ T11] RIP: 0010:unregister_netdevice_many_notify (net/core/dev.c:11120 (discriminator 1)) 
[ 62.091605][ T11] Code: 05 64 56 61 02 01 90 ba 32 1b 00 00 48 c7 c6 a0 9a 13 85 48 c7 c7 00 9c 13 85 e8 bf 59 08 fe 90 0f 0b 90 90 e9 8a fb ff ff 90 <0f> 0b 90 e9 aa fb ff ff e8 c7 5c 27 fe e9 37 fc ff ff 90 0f 0b 0f
All code
========
   0:	05 64 56 61 02       	add    $0x2615664,%eax
   5:	01 90 ba 32 1b 00    	add    %edx,0x1b32ba(%rax)
   b:	00 48 c7             	add    %cl,-0x39(%rax)
   e:	c6                   	(bad)
   f:	a0 9a 13 85 48 c7 c7 	movabs 0x9c00c7c74885139a,%al
  16:	00 9c 
  18:	13 85 e8 bf 59 08    	adc    0x859bfe8(%rbp),%eax
  1e:	fe                   	(bad)
  1f:	90                   	nop
  20:	0f 0b                	ud2
  22:	90                   	nop
  23:	90                   	nop
  24:	e9 8a fb ff ff       	jmp    0xfffffffffffffbb3
  29:	90                   	nop
  2a:*	0f 0b                	ud2		<-- trapping instruction
  2c:	90                   	nop
  2d:	e9 aa fb ff ff       	jmp    0xfffffffffffffbdc
  32:	e8 c7 5c 27 fe       	call   0xfffffffffe275cfe
  37:	e9 37 fc ff ff       	jmp    0xfffffffffffffc73
  3c:	90                   	nop
  3d:	0f 0b                	ud2
  3f:	0f                   	.byte 0xf

Code starting with the faulting instruction
===========================================
   0:	0f 0b                	ud2
   2:	90                   	nop
   3:	e9 aa fb ff ff       	jmp    0xfffffffffffffbb2
   8:	e8 c7 5c 27 fe       	call   0xfffffffffe275cd4
   d:	e9 37 fc ff ff       	jmp    0xfffffffffffffc49
  12:	90                   	nop
  13:	0f 0b                	ud2
  15:	0f                   	.byte 0xf
[   62.092657][   T11] RSP: 0018:ffffc900000bfb28 EFLAGS: 00010297
[   62.092976][   T11] RAX: ffff8880099c07d8 RBX: ffff888007b90000 RCX: ffffffff820c7967
[   62.093515][   T11] RDX: 1ffffffff0c6ff44 RSI: 0000000000000008 RDI: ffffffff8637fa20
[   62.093942][   T11] RBP: ffff888007b901c0 R08: 0000000000000000 R09: fffffbfff0c6ff44
[   62.094437][   T11] R10: ffffffff8637fa27 R11: ffffc900000bf621 R12: ffff8880099c0180
[   62.094857][   T11] R13: ffffc900000bfc00 R14: dffffc0000000000 R15: ffff8880099c0180
[   62.095414][   T11] FS:  0000000000000000(0000) GS:ffff888035600000(0000) knlGS:0000000000000000
[   62.095919][   T11] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   62.096286][   T11] CR2: 00007ffddb519618 CR3: 0000000007858003 CR4: 0000000000770ef0
[   62.096735][   T11] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[   62.097200][   T11] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[   62.097624][   T11] PKRU: 55555554
[   62.097833][   T11] Call Trace:
[   62.098010][   T11]  <TASK>
[ 62.098207][ T11] ? __warn (kernel/panic.c:677) 
[ 62.098428][ T11] ? unregister_netdevice_many_notify (net/core/dev.c:11120 (discriminator 1)) 
[ 62.098792][ T11] ? report_bug (lib/bug.c:201 lib/bug.c:219) 
[ 62.099050][ T11] ? handle_bug (arch/x86/kernel/traps.c:238) 
[ 62.099314][ T11] ? exc_invalid_op (arch/x86/kernel/traps.c:259 (discriminator 1)) 
[ 62.099591][ T11] ? asm_exc_invalid_op (./arch/x86/include/asm/idtentry.h:568) 
[ 62.099865][ T11] ? mutex_is_locked (./arch/x86/include/asm/atomic64_64.h:15 ./include/linux/atomic/atomic-arch-fallback.h:2569 ./include/linux/atomic/atomic-long.h:38 ./include/linux/atomic/atomic-instrumented.h:3161 kernel/locking/mutex.c:81 kernel/locking/mutex.c:91) 
[ 62.100133][ T11] ? unregister_netdevice_many_notify (net/core/dev.c:11120 (discriminator 1)) 
[ 62.100487][ T11] ? unregister_netdevice_many_notify (net/core/dev.c:6962 net/core/dev.c:11120) 
[ 62.100893][ T11] ? __pfx_unregister_netdevice_many_notify (net/core/dev.c:11035) 
[ 62.101275][ T11] ? mutex_is_locked (./arch/x86/include/asm/atomic64_64.h:15 ./include/linux/atomic/atomic-arch-fallback.h:2569 ./include/linux/atomic/atomic-long.h:38 ./include/linux/atomic/atomic-instrumented.h:3161 kernel/locking/mutex.c:81 kernel/locking/mutex.c:91) 
[ 62.101534][ T11] ? nexthop_net_exit_batch_rtnl (net/ipv4/nexthop.c:569 net/ipv4/nexthop.c:1918 net/ipv4/nexthop.c:2426 net/ipv4/nexthop.c:3754) 
[ 62.101873][ T11] cleanup_net (net/core/net_namespace.c:633) 
[ 62.102120][ T11] ? __pfx_lock_acquire.part.0 (kernel/locking/lockdep.c:5719) 
[ 62.102442][ T11] ? __pfx_cleanup_net (net/core/net_namespace.c:581) 
[ 62.102723][ T11] ? lock_acquire (./include/trace/events/lock.h:24 kernel/locking/lockdep.c:5725) 
[ 62.102974][ T11] ? process_one_work (kernel/workqueue.c:2609) 
[ 62.103285][ T11] process_one_work (kernel/workqueue.c:2633) 
[ 62.103594][ T11] ? hlock_class (./arch/x86/include/asm/bitops.h:227 ./arch/x86/include/asm/bitops.h:239 ./include/asm-generic/bitops/instrumented-non-atomic.h:142 kernel/locking/lockdep.c:228) 
[ 62.103835][ T11] ? __pfx_process_one_work (kernel/workqueue.c:2542) 
[ 62.104133][ T11] ? assign_work (kernel/workqueue.c:1101) 
[ 62.104391][ T11] worker_thread (kernel/workqueue.c:2700 kernel/workqueue.c:2787) 
[ 62.104681][ T11] ? __pfx_worker_thread (kernel/workqueue.c:2733) 
[ 62.104979][ T11] kthread (kernel/kthread.c:388) 
[ 62.105212][ T11] ? __pfx_kthread (kernel/kthread.c:341) 
[ 62.105467][ T11] ret_from_fork (arch/x86/kernel/process.c:147) 
[ 62.105714][ T11] ? __pfx_kthread (kernel/kthread.c:341) 
[ 62.105980][ T11] ret_from_fork_asm (arch/x86/entry/entry_64.S:250) 
| [   62.108743][   T11] ---[ end trace 0000000000000000 ]---
| [   62.111668][   T11] ------------[ cut here ]------------
| [ 62.111977][ T11] WARNING: CPU: 0 PID: 11 at net/core/dev.c:11120 unregister_netdevice_many_notify (net/core/dev.c:11120 (discriminator 1)) 
| [   62.112524][   T11] Modules linked in: vxlan ip6_udp_tunnel udp_tunnel
[   62.113442][   T11] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014
[   62.114068][   T11] Workqueue: netns cleanup_net
[ 62.114337][ T11] RIP: 0010:unregister_netdevice_many_notify (net/core/dev.c:11120 (discriminator 1)) 
[ 62.114709][ T11] Code: 05 64 56 61 02 01 90 ba 32 1b 00 00 48 c7 c6 a0 9a 13 85 48 c7 c7 00 9c 13 85 e8 bf 59 08 fe 90 0f 0b 90 90 e9 8a fb ff ff 90 <0f> 0b 90 e9 aa fb ff ff e8 c7 5c 27 fe e9 37 fc ff ff 90 0f 0b 0f
All code
========
   0:	05 64 56 61 02       	add    $0x2615664,%eax
   5:	01 90 ba 32 1b 00    	add    %edx,0x1b32ba(%rax)
   b:	00 48 c7             	add    %cl,-0x39(%rax)
   e:	c6                   	(bad)
   f:	a0 9a 13 85 48 c7 c7 	movabs 0x9c00c7c74885139a,%al
  16:	00 9c 
  18:	13 85 e8 bf 59 08    	adc    0x859bfe8(%rbp),%eax
  1e:	fe                   	(bad)
  1f:	90                   	nop
  20:	0f 0b                	ud2
  22:	90                   	nop
  23:	90                   	nop
  24:	e9 8a fb ff ff       	jmp    0xfffffffffffffbb3
  29:	90                   	nop
  2a:*	0f 0b                	ud2		<-- trapping instruction
  2c:	90                   	nop
  2d:	e9 aa fb ff ff       	jmp    0xfffffffffffffbdc
  32:	e8 c7 5c 27 fe       	call   0xfffffffffe275cfe
  37:	e9 37 fc ff ff       	jmp    0xfffffffffffffc73
  3c:	90                   	nop
  3d:	0f 0b                	ud2
  3f:	0f                   	.byte 0xf

Code starting with the faulting instruction
===========================================
   0:	0f 0b                	ud2
   2:	90                   	nop
   3:	e9 aa fb ff ff       	jmp    0xfffffffffffffbb2
   8:	e8 c7 5c 27 fe       	call   0xfffffffffe275cd4
   d:	e9 37 fc ff ff       	jmp    0xfffffffffffffc49
  12:	90                   	nop
  13:	0f 0b                	ud2
  15:	0f                   	.byte 0xf
[   62.115757][   T11] RSP: 0018:ffffc900000bfb28 EFLAGS: 00010297
[   62.116139][   T11] RAX: ffff888004b1e2d8 RBX: ffff888002748000 RCX: ffffffff820c7967
[   62.116599][   T11] RDX: 1ffffffff0c6ff44 RSI: 0000000000000008 RDI: ffffffff8637fa20
[   62.117037][   T11] RBP: ffff8880027481c0 R08: 0000000000000000 R09: fffffbfff0c6ff44
[   62.117503][   T11] R10: ffffffff8637fa27 R11: ffffc900000bf621 R12: ffff888004b1ee00
[   62.117959][   T11] R13: ffffc900000bfc00 R14: dffffc0000000000 R15: ffff888004b1ee00
[   62.118424][   T11] FS:  0000000000000000(0000) GS:ffff888035200000(0000) knlGS:0000000000000000
[   62.118922][   T11] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   62.119312][   T11] CR2: 00007f8277825270 CR3: 00000000058ae006 CR4: 0000000000770ef0
[   62.119787][   T11] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[   62.120250][   T11] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[   62.120682][   T11] PKRU: 55555554
[   62.120868][   T11] Call Trace:
[   62.121087][   T11]  <TASK>
[ 62.121267][ T11] ? __warn (kernel/panic.c:677) 
[ 62.121531][ T11] ? unregister_netdevice_many_notify (net/core/dev.c:11120 (discriminator 1)) 
[ 62.121921][ T11] ? report_bug (lib/bug.c:201 lib/bug.c:219) 
[ 62.122204][ T11] ? handle_bug (arch/x86/kernel/traps.c:238) 
[ 62.122437][ T11] ? exc_invalid_op (arch/x86/kernel/traps.c:259 (discriminator 1)) 
[ 62.122714][ T11] ? asm_exc_invalid_op (./arch/x86/include/asm/idtentry.h:568) 
[ 62.122985][ T11] ? mutex_is_locked (./arch/x86/include/asm/atomic64_64.h:15 ./include/linux/atomic/atomic-arch-fallback.h:2569 ./include/linux/atomic/atomic-long.h:38 ./include/linux/atomic/atomic-instrumented.h:3161 kernel/locking/mutex.c:81 kernel/locking/mutex.c:91) 
[ 62.123284][ T11] ? unregister_netdevice_many_notify (net/core/dev.c:11120 (discriminator 1)) 
[ 62.123671][ T11] ? unregister_netdevice_many_notify (net/core/dev.c:6962 net/core/dev.c:11120) 
[ 62.124047][ T11] ? __pfx_unregister_netdevice_many_notify (net/core/dev.c:11035) 
[ 62.124449][ T11] ? mutex_is_locked (./arch/x86/include/asm/atomic64_64.h:15 ./include/linux/atomic/atomic-arch-fallback.h:2569 ./include/linux/atomic/atomic-long.h:38 ./include/linux/atomic/atomic-instrumented.h:3161 kernel/locking/mutex.c:81 kernel/locking/mutex.c:91) 
[ 62.124700][ T11] ? nexthop_net_exit_batch_rtnl (net/ipv4/nexthop.c:569 net/ipv4/nexthop.c:1918 net/ipv4/nexthop.c:2426 net/ipv4/nexthop.c:3754) 
[ 62.125060][ T11] cleanup_net (net/core/net_namespace.c:633) 
[ 62.125303][ T11] ? __pfx_lock_acquire.part.0 (kernel/locking/lockdep.c:5719) 
[ 62.125644][ T11] ? __pfx_cleanup_net (net/core/net_namespace.c:581) 
[ 62.125925][ T11] ? lock_acquire (./include/trace/events/lock.h:24 kernel/locking/lockdep.c:5725) 
[ 62.126191][ T11] ? process_one_work (kernel/workqueue.c:2609) 
[ 62.126485][ T11] process_one_work (kernel/workqueue.c:2633) 
[ 62.126812][ T11] ? hlock_class (./arch/x86/include/asm/bitops.h:227 ./arch/x86/include/asm/bitops.h:239 ./include/asm-generic/bitops/instrumented-non-atomic.h:142 kernel/locking/lockdep.c:228) 
[ 62.127055][ T11] ? __pfx_process_one_work (kernel/workqueue.c:2542) 
[ 62.127402][ T11] ? assign_work (kernel/workqueue.c:1101) 
[ 62.127652][ T11] worker_thread (kernel/workqueue.c:2700 kernel/workqueue.c:2787) 
[ 62.127938][ T11] ? __pfx_worker_thread (kernel/workqueue.c:2733) 
[ 62.128271][ T11] kthread (kernel/kthread.c:388) 
[ 62.128483][ T11] ? __pfx_kthread (kernel/kthread.c:341) 
[ 62.128777][ T11] ret_from_fork (arch/x86/kernel/process.c:147) 
[ 62.129011][ T11] ? __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