======================================
| [  206.716015] ------------[ cut here ]------------
| [  206.716207] refcount_t: underflow; use-after-free.
| [  206.716297] WARNING: CPU: 2 PID: 66 at lib/refcount.c:28 refcount_warn_saturate (lib/refcount.c:28 (discriminator 3))
| [  206.716396] Modules linked in: act_gact cls_flower vxlan ip6_udp_tunnel udp_tunnel bridge stp llc sch_ingress vrf veth
[  206.716625] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[  206.716703] Workqueue: netns cleanup_net
[  206.716770] RIP: 0010:refcount_warn_saturate (lib/refcount.c:28 (discriminator 3))
[  206.716868] Code: 8b e8 18 df ba ff 90 0f 0b 90 90 c3 80 3d f9 da eb 00 00 75 89 c6 05 f0 da eb 00 01 90 48 c7 c7 28 e0 11 8b e8 f5 de ba ff 90 <0f> 0b 90 90 c3 80 3d d4 da eb 00 00 0f 85 62 ff ff ff c6 05 c7 da
All code
========
   0:	8b e8                	mov    %eax,%ebp
   2:	18 df                	sbb    %bl,%bh
   4:	ba ff 90 0f 0b       	mov    $0xb0f90ff,%edx
   9:	90                   	nop
   a:	90                   	nop
   b:	c3                   	ret
   c:	80 3d f9 da eb 00 00 	cmpb   $0x0,0xebdaf9(%rip)        # 0xebdb0c
  13:	75 89                	jne    0xffffffffffffff9e
  15:	c6 05 f0 da eb 00 01 	movb   $0x1,0xebdaf0(%rip)        # 0xebdb0c
  1c:	90                   	nop
  1d:	48 c7 c7 28 e0 11 8b 	mov    $0xffffffff8b11e028,%rdi
  24:	e8 f5 de ba ff       	call   0xffffffffffbadf1e
  29:	90                   	nop
  2a:*	0f 0b                	ud2		<-- trapping instruction
  2c:	90                   	nop
  2d:	90                   	nop
  2e:	c3                   	ret
  2f:	80 3d d4 da eb 00 00 	cmpb   $0x0,0xebdad4(%rip)        # 0xebdb0a
  36:	0f 85 62 ff ff ff    	jne    0xffffffffffffff9e
  3c:	c6                   	.byte 0xc6
  3d:	05                   	.byte 0x5
  3e:	c7                   	(bad)
  3f:	da                   	.byte 0xda

Code starting with the faulting instruction
===========================================
   0:	0f 0b                	ud2
   2:	90                   	nop
   3:	90                   	nop
   4:	c3                   	ret
   5:	80 3d d4 da eb 00 00 	cmpb   $0x0,0xebdad4(%rip)        # 0xebdae0
   c:	0f 85 62 ff ff ff    	jne    0xffffffffffffff74
  12:	c6                   	.byte 0xc6
  13:	05                   	.byte 0x5
  14:	c7                   	(bad)
  15:	da                   	.byte 0xda
[  206.717072] RSP: 0018:ffffa6f18024fd50 EFLAGS: 00010286
[  206.717129] RAX: 0000000000000000 RBX: ffffa6f18024fd60 RCX: 00000000ffffdfff
[  206.717201] RDX: 0000000000000000 RSI: 00000000ffffffea RDI: 0000000000000001
[  206.717271] RBP: ffffa6f18024f868 R08: ffffffff8b556a28 R09: 00000000ffffdfff
[  206.717341] R10: ffffffff8b476a40 R11: ffffffff8b526a40 R12: dead000000000122
[  206.717412] R13: 00000000fffe931a R14: 0000000000000001 R15: ffff90dcc91a1000
[  206.717484] FS:  0000000000000000(0000) GS:ffff90dd730d9000(0000) knlGS:0000000000000000
[  206.717556] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  206.717618] CR2: 00007f10ff64ea70 CR3: 00000000039c3006 CR4: 0000000000772ef0
[  206.717690] PKRU: 55555554
[  206.717729] Call Trace:
[  206.717771]  <TASK>
[  206.717821]  netdev_run_todo (./include/linux/list.h:381 net/core/dev.c:11670)
[  206.717882]  ops_undo_list (net/core/net_namespace.c:190 net/core/net_namespace.c:248)
[  206.717932]  cleanup_net (net/core/net_namespace.c:698)
[  206.717991]  process_one_work (kernel/workqueue.c:3268)
[  206.718044]  worker_thread (kernel/workqueue.c:3340 kernel/workqueue.c:3427)
[  206.718092]  ? rescuer_thread (kernel/workqueue.c:3373)
[  206.718141]  kthread (kernel/kthread.c:463)
[  206.718189]  ? kthreads_online_cpu (kernel/kthread.c:412)
[  206.718250]  ? kthreads_online_cpu (kernel/kthread.c:412)
[  206.718320]  ret_from_fork (arch/x86/kernel/process.c:164)
[  206.718379]  ? kthreads_online_cpu (kernel/kthread.c:412)


Finger prints:
refcount_warn_saturate:netdev_run_todo:ops_undo_list:cleanup_net:process_one_work