======================================
| xx__-> [    8.449499] ------------[ cut here ]------------
| [    8.449596] refcount_t: underflow; use-after-free.
| [    8.449683] WARNING: CPU: 0 PID: 67 at lib/refcount.c:28 refcount_warn_saturate (lib/refcount.c:28 (discriminator 3))
| [    8.449790] Modules linked in: nft_fib_inet nft_fib_ipv4 nft_fib_ipv6 nft_fib ip6t_rpfilter ipt_rpfilter xt_tcpudp nft_compat nf_tables x_tables dummy veth
[    8.450074] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[    8.450151] Workqueue: netns cleanup_net
[    8.450202] RIP: 0010:refcount_warn_saturate (lib/refcount.c:28 (discriminator 3))
[    8.450269] Code: bd e8 18 ed b9 ff 90 0f 0b 90 90 c3 80 3d d9 ea ea 00 00 75 89 c6 05 d0 ea ea 00 01 90 48 c7 c7 78 de 31 bd e8 f5 ec b9 ff 90 <0f> 0b 90 90 c3 80 3d b4 ea ea 00 00 0f 85 62 ff ff ff c6 05 a7 ea
All code
========
   0:	bd e8 18 ed b9       	mov    $0xb9ed18e8,%ebp
   5:	ff 90 0f 0b 90 90    	call   *-0x6f6ff4f1(%rax)
   b:	c3                   	ret
   c:	80 3d d9 ea ea 00 00 	cmpb   $0x0,0xeaead9(%rip)        # 0xeaeaec
  13:	75 89                	jne    0xffffffffffffff9e
  15:	c6 05 d0 ea ea 00 01 	movb   $0x1,0xeaead0(%rip)        # 0xeaeaec
  1c:	90                   	nop
  1d:	48 c7 c7 78 de 31 bd 	mov    $0xffffffffbd31de78,%rdi
  24:	e8 f5 ec b9 ff       	call   0xffffffffffb9ed1e
  29:	90                   	nop
  2a:*	0f 0b                	ud2		<-- trapping instruction
  2c:	90                   	nop
  2d:	90                   	nop
  2e:	c3                   	ret
  2f:	80 3d b4 ea ea 00 00 	cmpb   $0x0,0xeaeab4(%rip)        # 0xeaeaea
  36:	0f 85 62 ff ff ff    	jne    0xffffffffffffff9e
  3c:	c6                   	.byte 0xc6
  3d:	05                   	.byte 0x5
  3e:	a7                   	cmpsl  %es:(%rdi),%ds:(%rsi)
  3f:	ea                   	(bad)

Code starting with the faulting instruction
===========================================
   0:	0f 0b                	ud2
   2:	90                   	nop
   3:	90                   	nop
   4:	c3                   	ret
   5:	80 3d b4 ea ea 00 00 	cmpb   $0x0,0xeaeab4(%rip)        # 0xeaeac0
   c:	0f 85 62 ff ff ff    	jne    0xffffffffffffff74
  12:	c6                   	.byte 0xc6
  13:	05                   	.byte 0x5
  14:	a7                   	cmpsl  %es:(%rdi),%ds:(%rsi)
  15:	ea                   	(bad)
[    8.450483] RSP: 0018:ffffad7280253d50 EFLAGS: 00010286
[    8.450552] RAX: 0000000000000000 RBX: ffffad7280253d60 RCX: 00000000ffffdfff
[    8.450642] RDX: 0000000000000000 RSI: 00000000ffffffea RDI: 0000000000000001
[    8.450730] RBP: ffffad7280253868 R08: ffffffffbd756d28 R09: 00000000ffffdfff
[    8.450818] R10: ffffffffbd676d40 R11: ffffffffbd726d40 R12: dead000000000122
[    8.450905] R13: 00000000fffb8c9f R14: 0000000000000001 R15: ffff914cc112d000
[    8.450995] FS:  0000000000000000(0000) GS:ffff914d40dd8000(0000) knlGS:0000000000000000
[    8.451095] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[    8.451188] CR2: 00007fa213ec9000 CR3: 000000003a441003 CR4: 0000000000772ef0
[    8.451281] PKRU: 55555554
[    8.451309] Call Trace:
[    8.451342]  <TASK>
[    8.451379]  netdev_run_todo (./include/linux/list.h:381 net/core/dev.c:11670)
[    8.451448]  ops_undo_list (net/core/net_namespace.c:190 net/core/net_namespace.c:248)
[    8.451510]  cleanup_net (net/core/net_namespace.c:698)
[    8.451562]  process_one_work (kernel/workqueue.c:3268)
[    8.451628]  worker_thread (kernel/workqueue.c:3340 kernel/workqueue.c:3427)
[    8.451678]  ? rescuer_thread (kernel/workqueue.c:3373)
[    8.451733]  kthread (kernel/kthread.c:463)
[    8.451786]  ? kthreads_online_cpu (kernel/kthread.c:412)
[    8.451843]  ? kthreads_online_cpu (kernel/kthread.c:412)
[    8.451904]  ret_from_fork (arch/x86/kernel/process.c:164)
[    8.451964]  ? kthreads_online_cpu (kernel/kthread.c:412)


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