======================================
| [    3.016486] ------------[ cut here ]------------
| [    3.016562] refcount_t: underflow; use-after-free.
| [    3.016636] WARNING: CPU: 0 PID: 69 at lib/refcount.c:28 refcount_warn_saturate (lib/refcount.c:28 (discriminator 3))
| [    3.016731] Modules linked in:
[    3.017011] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[    3.017199] Workqueue: netns cleanup_net
[    3.017259] RIP: 0010:refcount_warn_saturate (lib/refcount.c:28 (discriminator 3))
[    3.017317] Code: b8 e8 88 98 ba ff 90 0f 0b 90 90 c3 80 3d 69 b4 eb 00 00 75 89 c6 05 60 b4 eb 00 01 90 48 c7 c7 98 6e 34 b8 e8 65 98 ba ff 90 <0f> 0b 90 90 c3 80 3d 44 b4 eb 00 00 0f 85 62 ff ff ff c6 05 37 b4
All code
========
   0:	b8 e8 88 98 ba       	mov    $0xba9888e8,%eax
   5:	ff 90 0f 0b 90 90    	call   *-0x6f6ff4f1(%rax)
   b:	c3                   	ret
   c:	80 3d 69 b4 eb 00 00 	cmpb   $0x0,0xebb469(%rip)        # 0xebb47c
  13:	75 89                	jne    0xffffffffffffff9e
  15:	c6 05 60 b4 eb 00 01 	movb   $0x1,0xebb460(%rip)        # 0xebb47c
  1c:	90                   	nop
  1d:	48 c7 c7 98 6e 34 b8 	mov    $0xffffffffb8346e98,%rdi
  24:	e8 65 98 ba ff       	call   0xffffffffffba988e
  29:	90                   	nop
  2a:*	0f 0b                	ud2		<-- trapping instruction
  2c:	90                   	nop
  2d:	90                   	nop
  2e:	c3                   	ret
  2f:	80 3d 44 b4 eb 00 00 	cmpb   $0x0,0xebb444(%rip)        # 0xebb47a
  36:	0f 85 62 ff ff ff    	jne    0xffffffffffffff9e
  3c:	c6                   	.byte 0xc6
  3d:	05                   	.byte 0x5
  3e:	37                   	(bad)
  3f:	b4                   	.byte 0xb4

Code starting with the faulting instruction
===========================================
   0:	0f 0b                	ud2
   2:	90                   	nop
   3:	90                   	nop
   4:	c3                   	ret
   5:	80 3d 44 b4 eb 00 00 	cmpb   $0x0,0xebb444(%rip)        # 0xebb450
   c:	0f 85 62 ff ff ff    	jne    0xffffffffffffff74
  12:	c6                   	.byte 0xc6
  13:	05                   	.byte 0x5
  14:	37                   	(bad)
  15:	b4                   	.byte 0xb4
[    3.017508] RSP: 0018:ffffb08100267d50 EFLAGS: 00010286
[    3.017568] RAX: 0000000000000000 RBX: ffffb08100267d60 RCX: 00000000ffffdfff
[    3.017644] RDX: 0000000000000000 RSI: 00000000ffffffea RDI: 0000000000000001
[    3.017722] RBP: ffffb08100267878 R08: ffffffffb8756a28 R09: 00000000ffffdfff
[    3.017816] R10: ffffffffb8676a40 R11: ffffffffb8726a40 R12: dead000000000122
[    3.017901] R13: 00000000fffb7764 R14: 0000000000000001 R15: ffff933044eaa000
[    3.017990] FS:  0000000000000000(0000) GS:ffff9330c5db7000(0000) knlGS:0000000000000000
[    3.018072] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[    3.018144] CR2: 00007f8f066294d8 CR3: 000000000c441004 CR4: 0000000000772ef0
[    3.018223] PKRU: 55555554
[    3.018256] Call Trace:
[    3.018289]  <TASK>
[    3.018312]  netdev_run_todo (./include/linux/list.h:381 net/core/dev.c:11670)
[    3.018363]  ops_undo_list (net/core/net_namespace.c:190 net/core/net_namespace.c:248)
[    3.018407]  cleanup_net (net/core/net_namespace.c:698)
[    3.018450]  process_one_work (kernel/workqueue.c:3268)
[    3.018503]  worker_thread (kernel/workqueue.c:3340 kernel/workqueue.c:3427)
[    3.018560]  ? rescuer_thread (kernel/workqueue.c:3373)
[    3.018595]  kthread (kernel/kthread.c:463)
[    3.018641]  ? kthreads_online_cpu (kernel/kthread.c:412)
[    3.018705]  ? kthreads_online_cpu (kernel/kthread.c:412)
[    3.018755]  ret_from_fork (arch/x86/kernel/process.c:164)
[    3.018804]  ? kthreads_online_cpu (kernel/kthread.c:412)


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