======================================
| [ 1662.757521][   T11] br2: port 1(vethhv-21) entered disabled state
| [ 1662.799086][   T11] ------------[ cut here ]------------
| [ 1662.799417][ T11] WARNING: CPU: 1 PID: 11 at net/core/dev.c:11120 unregister_netdevice_many_notify (net/core/dev.c:11120 (discriminator 1)) 
| [ 1662.799954][   T11] Modules linked in: vxlan ip6_udp_tunnel udp_tunnel poly1305_generic libpoly1305 chacha_generic libchacha chacha20poly1305 tls sha1_generic xfrm_user xt_policy nft_compat nf_tables libcrc32c
[ 1662.801448][   T11] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014
[ 1662.802116][   T11] Workqueue: netns cleanup_net
[ 1662.802387][ T11] RIP: 0010:unregister_netdevice_many_notify (net/core/dev.c:11120 (discriminator 1)) 
[ 1662.802790][ T11] Code: 05 e1 58 61 02 01 90 ba 32 1b 00 00 48 c7 c6 a0 9a b3 93 48 c7 c7 00 9c b3 93 e8 7f 60 08 fe 90 0f 0b 90 90 e9 8a fb ff ff 90 <0f> 0b 90 e9 aa fb ff ff e8 87 63 27 fe e9 37 fc ff ff 90 0f 0b 0f
All code
========
   0:	05 e1 58 61 02       	add    $0x26158e1,%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 b3 93 48 c7 c7 	movabs 0x9c00c7c74893b39a,%al
  16:	00 9c 
  18:	b3 93                	mov    $0x93,%bl
  1a:	e8 7f 60 08 fe       	call   0xfffffffffe08609e
  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 87 63 27 fe       	call   0xfffffffffe2763be
  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 87 63 27 fe       	call   0xfffffffffe276394
   d:	e9 37 fc ff ff       	jmp    0xfffffffffffffc49
  12:	90                   	nop
  13:	0f 0b                	ud2
  15:	0f                   	.byte 0xf
[ 1662.803832][   T11] RSP: 0018:ffffc900000bfb28 EFLAGS: 00010212
[ 1662.804186][   T11] RAX: ffff88800a13ae18 RBX: ffff88800a178000 RCX: ffffffff90ac7967
[ 1662.804615][   T11] RDX: 1ffffffff29aff24 RSI: 0000000000000008 RDI: ffffffff94d7f920
[ 1662.805028][   T11] RBP: ffff88800a1781c0 R08: 0000000000000000 R09: fffffbfff29aff24
[ 1662.805485][   T11] R10: ffffffff94d7f927 R11: ffffc900000bf621 R12: ffff88800a13af40
[ 1662.805907][   T11] R13: ffffc900000bfc00 R14: dffffc0000000000 R15: ffff88800a13af40
[ 1662.806330][   T11] FS:  0000000000000000(0000) GS:ffff888035600000(0000) knlGS:0000000000000000
[ 1662.806841][   T11] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 1662.807207][   T11] CR2: 000055fbfa4c4dec CR3: 0000000022534004 CR4: 0000000000770ef0
[ 1662.807627][   T11] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 1662.808056][   T11] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 1662.808499][   T11] PKRU: 55555554
[ 1662.808708][   T11] Call Trace:
[ 1662.808885][   T11]  <TASK>
[ 1662.809051][ T11] ? __warn (kernel/panic.c:677) 
[ 1662.809288][ T11] ? unregister_netdevice_many_notify (net/core/dev.c:11120 (discriminator 1)) 
[ 1662.809656][ T11] ? report_bug (lib/bug.c:201 lib/bug.c:219) 
[ 1662.809908][ T11] ? handle_bug (arch/x86/kernel/traps.c:238) 
[ 1662.810164][ T11] ? exc_invalid_op (arch/x86/kernel/traps.c:259 (discriminator 1)) 
[ 1662.810421][ T11] ? asm_exc_invalid_op (./arch/x86/include/asm/idtentry.h:568) 
[ 1662.810717][ 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) 
[ 1662.810971][ T11] ? unregister_netdevice_many_notify (net/core/dev.c:11120 (discriminator 1)) 
[ 1662.811338][ T11] ? unregister_netdevice_many_notify (net/core/dev.c:6962 net/core/dev.c:11120) 
[ 1662.811703][ T11] ? __pfx_unregister_netdevice_many_notify (net/core/dev.c:11035) 
[ 1662.812056][ 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) 
[ 1662.812316][ 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) 
[ 1662.812632][ T11] cleanup_net (net/core/net_namespace.c:633) 
[ 1662.812868][ T11] ? __pfx_lock_acquire.part.0 (kernel/locking/lockdep.c:5719) 
[ 1662.813170][ T11] ? __pfx_cleanup_net (net/core/net_namespace.c:581) 
[ 1662.813435][ T11] ? lock_acquire (./include/trace/events/lock.h:24 kernel/locking/lockdep.c:5725) 
[ 1662.813680][ T11] ? process_one_work (kernel/workqueue.c:2609) 
[ 1662.813955][ T11] process_one_work (kernel/workqueue.c:2633) 
[ 1662.814231][ 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) 
[ 1662.814472][ T11] ? __pfx_process_one_work (kernel/workqueue.c:2542) 
[ 1662.814763][ T11] ? assign_work (kernel/workqueue.c:1101) 
[ 1662.815010][ T11] worker_thread (kernel/workqueue.c:2700 kernel/workqueue.c:2787) 
[ 1662.815282][ T11] ? __pfx_worker_thread (kernel/workqueue.c:2733) 
[ 1662.815550][ T11] kthread (kernel/kthread.c:388) 
[ 1662.815766][ T11] ? __pfx_kthread (kernel/kthread.c:341) 
[ 1662.816009][ T11] ret_from_fork (arch/x86/kernel/process.c:147) 
[ 1662.816253][ T11] ? __pfx_kthread (kernel/kthread.c:341) 
[ 1662.816535][ T11] ret_from_fork_asm (arch/x86/entry/entry_64.S:250) 
| [ 1662.819393][   T11] ---[ end trace 0000000000000000 ]---
| [ 1662.823413][   T11] ------------[ cut here ]------------
| [ 1662.823738][ T11] WARNING: CPU: 1 PID: 11 at net/core/dev.c:11120 unregister_netdevice_many_notify (net/core/dev.c:11120 (discriminator 1)) 
| [ 1662.824301][   T11] Modules linked in: vxlan ip6_udp_tunnel udp_tunnel poly1305_generic libpoly1305 chacha_generic libchacha chacha20poly1305 tls sha1_generic xfrm_user xt_policy nft_compat nf_tables libcrc32c
[ 1662.825843][   T11] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014
[ 1662.827128][   T11] Workqueue: netns cleanup_net
[ 1662.827455][ T11] RIP: 0010:unregister_netdevice_many_notify (net/core/dev.c:11120 (discriminator 1)) 
[ 1662.827822][ T11] Code: 05 e1 58 61 02 01 90 ba 32 1b 00 00 48 c7 c6 a0 9a b3 93 48 c7 c7 00 9c b3 93 e8 7f 60 08 fe 90 0f 0b 90 90 e9 8a fb ff ff 90 <0f> 0b 90 e9 aa fb ff ff e8 87 63 27 fe e9 37 fc ff ff 90 0f 0b 0f
All code
========
   0:	05 e1 58 61 02       	add    $0x26158e1,%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 b3 93 48 c7 c7 	movabs 0x9c00c7c74893b39a,%al
  16:	00 9c 
  18:	b3 93                	mov    $0x93,%bl
  1a:	e8 7f 60 08 fe       	call   0xfffffffffe08609e
  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 87 63 27 fe       	call   0xfffffffffe2763be
  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 87 63 27 fe       	call   0xfffffffffe276394
   d:	e9 37 fc ff ff       	jmp    0xfffffffffffffc49
  12:	90                   	nop
  13:	0f 0b                	ud2
  15:	0f                   	.byte 0xf
[ 1662.828885][   T11] RSP: 0018:ffffc900000bfb28 EFLAGS: 00010212
[ 1662.829338][   T11] RAX: ffff888005f35318 RBX: ffff88800a828000 RCX: ffffffff90ac7967
[ 1662.829767][   T11] RDX: 1ffffffff29aff24 RSI: 0000000000000008 RDI: ffffffff94d7f920
[ 1662.830246][   T11] RBP: ffff88800a8281c0 R08: 0000000000000000 R09: fffffbfff29aff24
[ 1662.830697][   T11] R10: ffffffff94d7f927 R11: ffffc900000bf621 R12: ffff8880082bf300
[ 1662.831119][   T11] R13: ffffc900000bfc00 R14: dffffc0000000000 R15: ffff8880082bf300
[ 1662.831598][   T11] FS:  0000000000000000(0000) GS:ffff888035600000(0000) knlGS:0000000000000000
[ 1662.832057][   T11] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 1662.832460][   T11] CR2: 000055fbfa4c4dec CR3: 0000000022534004 CR4: 0000000000770ef0
[ 1662.832868][   T11] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 1662.833339][   T11] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 1662.833744][   T11] PKRU: 55555554
[ 1662.833931][   T11] Call Trace:
[ 1662.834107][   T11]  <TASK>
[ 1662.834325][ T11] ? __warn (kernel/panic.c:677) 
[ 1662.834544][ T11] ? unregister_netdevice_many_notify (net/core/dev.c:11120 (discriminator 1)) 
[ 1662.834883][ T11] ? report_bug (lib/bug.c:201 lib/bug.c:219) 
[ 1662.835128][ T11] ? handle_bug (arch/x86/kernel/traps.c:238) 
[ 1662.835431][ T11] ? exc_invalid_op (arch/x86/kernel/traps.c:259 (discriminator 1)) 
[ 1662.835678][ T11] ? asm_exc_invalid_op (./arch/x86/include/asm/idtentry.h:568) 
[ 1662.835951][ 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) 
[ 1662.836268][ T11] ? unregister_netdevice_many_notify (net/core/dev.c:11120 (discriminator 1)) 
[ 1662.836611][ T11] ? unregister_netdevice_many_notify (net/core/dev.c:6962 net/core/dev.c:11120) 
[ 1662.836967][ T11] ? __pfx_unregister_netdevice_many_notify (net/core/dev.c:11035) 
[ 1662.837385][ 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) 
[ 1662.837639][ 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) 
[ 1662.837986][ T11] cleanup_net (net/core/net_namespace.c:633) 
[ 1662.838320][ T11] ? __pfx_lock_acquire.part.0 (kernel/locking/lockdep.c:5719) 
[ 1662.838634][ T11] ? __pfx_cleanup_net (net/core/net_namespace.c:581) 
[ 1662.838908][ T11] ? lock_acquire (./include/trace/events/lock.h:24 kernel/locking/lockdep.c:5725) 
[ 1662.839261][ T11] ? process_one_work (kernel/workqueue.c:2609) 
[ 1662.839567][ T11] process_one_work (kernel/workqueue.c:2633) 
[ 1662.839851][ 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) 
[ 1662.840099][ T11] ? __pfx_process_one_work (kernel/workqueue.c:2542) 
[ 1662.840530][ T11] ? assign_work (kernel/workqueue.c:1101) 
[ 1662.840807][ T11] worker_thread (kernel/workqueue.c:2700 kernel/workqueue.c:2787) 
[ 1662.841087][ T11] ? __pfx_worker_thread (kernel/workqueue.c:2733) 
[ 1662.841430][ T11] kthread (kernel/kthread.c:388) 
[ 1662.841665][ T11] ? __pfx_kthread (kernel/kthread.c:341) 
[ 1662.841934][ T11] ret_from_fork (arch/x86/kernel/process.c:147) 
[ 1662.842240][ 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