======================================
| [ 1223.770978][   T11] br0: port 1(vxlan0) entered disabled state
| [ 1223.826153][   T11] ------------[ cut here ]------------
| [ 1223.826658][ T11] WARNING: CPU: 2 PID: 11 at net/core/dev.c:11120 unregister_netdevice_many_notify (net/core/dev.c:11120 (discriminator 1)) 
| [ 1223.828612][   T11] Modules linked in: xt_conntrack sctp_diag sctp nft_chain_nat xt_nat nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 nft_compat nf_tables libcrc32c vxlan ip6_udp_tunnel udp_tunnel
[ 1223.830908][   T11] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014
[ 1223.832060][   T11] Workqueue: netns cleanup_net
[ 1223.832640][ T11] RIP: 0010:unregister_netdevice_many_notify (net/core/dev.c:11120 (discriminator 1)) 
[ 1223.833419][ T11] Code: 05 e1 58 61 02 01 90 ba 32 1b 00 00 48 c7 c6 a0 9a 33 9d 48 c7 c7 00 9c 33 9d 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 33 9d 48 c7 c7 	movabs 0x9c00c7c7489d339a,%al
  16:	00 9c 
  18:	33 9d e8 7f 60 08    	xor    0x8607fe8(%rbp),%ebx
  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 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
[ 1223.835439][   T11] RSP: 0018:ffffc900000bfb28 EFLAGS: 00010216
[ 1223.835995][   T11] RAX: ffff888004995bd8 RBX: ffff888008e78000 RCX: ffffffff9a2c7967
[ 1223.836810][   T11] RDX: 1ffffffff3caff24 RSI: 0000000000000008 RDI: ffffffff9e57f920
[ 1223.837626][   T11] RBP: ffff888008e781c0 R08: 0000000000000000 R09: fffffbfff3caff24
[ 1223.838432][   T11] R10: ffffffff9e57f927 R11: ffffc900000bf621 R12: ffff888004995800
[ 1223.839111][   T11] R13: ffffc900000bfc00 R14: dffffc0000000000 R15: ffff888004995800
[ 1223.839913][   T11] FS:  0000000000000000(0000) GS:ffff888035a00000(0000) knlGS:0000000000000000
[ 1223.840793][   T11] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 1223.841463][   T11] CR2: 0000560e2984bdec CR3: 000000000e734002 CR4: 0000000000770ef0
[ 1223.842104][   T11] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 1223.842861][   T11] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 1223.843675][   T11] PKRU: 55555554
[ 1223.843961][   T11] Call Trace:
[ 1223.844356][   T11]  <TASK>
[ 1223.844597][ T11] ? __warn (kernel/panic.c:677) 
[ 1223.844931][ T11] ? unregister_netdevice_many_notify (net/core/dev.c:11120 (discriminator 1)) 
[ 1223.845487][ T11] ? report_bug (lib/bug.c:201 lib/bug.c:219) 
[ 1223.845878][ T11] ? handle_bug (arch/x86/kernel/traps.c:238) 
[ 1223.846232][ T11] ? exc_invalid_op (arch/x86/kernel/traps.c:259 (discriminator 1)) 
[ 1223.846595][ T11] ? asm_exc_invalid_op (./arch/x86/include/asm/idtentry.h:568) 
[ 1223.846998][ 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) 
[ 1223.847392][ T11] ? unregister_netdevice_many_notify (net/core/dev.c:11120 (discriminator 1)) 
[ 1223.847888][ T11] ? unregister_netdevice_many_notify (net/core/dev.c:6962 net/core/dev.c:11120) 
[ 1223.848440][ T11] ? __pfx_unregister_netdevice_many_notify (net/core/dev.c:11035) 
[ 1223.848821][ 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) 
[ 1223.849109][ 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) 
[ 1223.849460][ T11] cleanup_net (net/core/net_namespace.c:633) 
[ 1223.849716][ T11] ? __pfx_lock_acquire.part.0 (kernel/locking/lockdep.c:5719) 
[ 1223.850059][ T11] ? __pfx_cleanup_net (net/core/net_namespace.c:581) 
[ 1223.850508][ T11] ? lock_acquire (./include/trace/events/lock.h:24 kernel/locking/lockdep.c:5725) 
[ 1223.850873][ T11] ? process_one_work (kernel/workqueue.c:2609) 
[ 1223.851170][ T11] process_one_work (kernel/workqueue.c:2633) 
[ 1223.851527][ 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) 
[ 1223.851791][ T11] ? __pfx_process_one_work (kernel/workqueue.c:2542) 
[ 1223.852114][ T11] ? assign_work (kernel/workqueue.c:1101) 
[ 1223.852383][ T11] worker_thread (kernel/workqueue.c:2700 kernel/workqueue.c:2787) 
[ 1223.852667][ T11] ? __pfx_worker_thread (kernel/workqueue.c:2733) 
[ 1223.852961][ T11] kthread (kernel/kthread.c:388) 
[ 1223.853214][ T11] ? __pfx_kthread (kernel/kthread.c:341) 
[ 1223.853462][ T11] ret_from_fork (arch/x86/kernel/process.c:147) 
[ 1223.853721][ T11] ? __pfx_kthread (kernel/kthread.c:341) 


Finger prints:
unregister_netdevice_many_notify:cleanup_net:process_one_work:worker_thread