======================================
| [    2.863773] ------------[ cut here ]------------
| [    2.863836] refcount_t: underflow; use-after-free.
| [    2.863891] WARNING: CPU: 0 PID: 12 at lib/refcount.c:28 refcount_warn_saturate (lib/refcount.c:28 (discriminator 3))
| [    2.863968] Modules linked in:
[    2.864064] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[    2.864105] Workqueue: netns cleanup_net
[    2.864140] RIP: 0010:refcount_warn_saturate (lib/refcount.c:28 (discriminator 3))
[    2.864179] Code: 9d e8 e8 54 ba ff 90 0f 0b 90 90 c3 80 3d 00 e6 2b 01 00 75 89 c6 05 f7 e5 2b 01 01 90 48 c7 c7 f8 48 55 9d e8 c5 54 ba ff 90 <0f> 0b 90 90 c3 80 3d db e5 2b 01 00 0f 85 62 ff ff ff c6 05 ce e5
All code
========
   0:	9d                   	popf
   1:	e8 e8 54 ba ff       	call   0xffffffffffba54ee
   6:	90                   	nop
   7:	0f 0b                	ud2
   9:	90                   	nop
   a:	90                   	nop
   b:	c3                   	ret
   c:	80 3d 00 e6 2b 01 00 	cmpb   $0x0,0x12be600(%rip)        # 0x12be613
  13:	75 89                	jne    0xffffffffffffff9e
  15:	c6 05 f7 e5 2b 01 01 	movb   $0x1,0x12be5f7(%rip)        # 0x12be613
  1c:	90                   	nop
  1d:	48 c7 c7 f8 48 55 9d 	mov    $0xffffffff9d5548f8,%rdi
  24:	e8 c5 54 ba ff       	call   0xffffffffffba54ee
  29:	90                   	nop
  2a:*	0f 0b                	ud2		<-- trapping instruction
  2c:	90                   	nop
  2d:	90                   	nop
  2e:	c3                   	ret
  2f:	80 3d db e5 2b 01 00 	cmpb   $0x0,0x12be5db(%rip)        # 0x12be611
  36:	0f 85 62 ff ff ff    	jne    0xffffffffffffff9e
  3c:	c6                   	.byte 0xc6
  3d:	05                   	.byte 0x5
  3e:	ce                   	(bad)
  3f:	e5                   	.byte 0xe5

Code starting with the faulting instruction
===========================================
   0:	0f 0b                	ud2
   2:	90                   	nop
   3:	90                   	nop
   4:	c3                   	ret
   5:	80 3d db e5 2b 01 00 	cmpb   $0x0,0x12be5db(%rip)        # 0x12be5e7
   c:	0f 85 62 ff ff ff    	jne    0xffffffffffffff74
  12:	c6                   	.byte 0xc6
  13:	05                   	.byte 0x5
  14:	ce                   	(bad)
  15:	e5                   	.byte 0xe5
[    2.864302] RSP: 0000:ffffbb6600067d50 EFLAGS: 00010286
[    2.864342] RAX: 0000000000000000 RBX: ffffbb6600067d60 RCX: 00000000ffffdfff
[    2.864392] RDX: 0000000000000000 RSI: 00000000ffffffea RDI: 0000000000000001
[    2.864441] RBP: ffffbb6600067858 R08: ffffffff9dd5ba28 R09: 00000000ffffdfff
[    2.864492] R10: ffffffff9dc7ba40 R11: ffffffff9dd2ba40 R12: dead000000000122
[    2.864541] R13: 00000000fffb76d3 R14: 0000000000000001 R15: ffff97f20664a000
[    2.864593] FS:  0000000000000000(0000) GS:ffff97f2a0791000(0000) knlGS:0000000000000000
[    2.864649] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[    2.864709] CR2: 00007f267208bb30 CR3: 0000000006663003 CR4: 0000000000772ef0
[    2.864763] PKRU: 55555554
[    2.864784] Call Trace:
[    2.864803]  <TASK>
[    2.864824]  netdev_run_todo (./include/linux/list.h:381 net/core/dev.c:11670)
[    2.864857]  ops_undo_list (net/core/net_namespace.c:190 net/core/net_namespace.c:248)
[    2.864895]  cleanup_net (net/core/net_namespace.c:698)
[    2.864929]  process_one_work (kernel/workqueue.c:3268)
[    2.864965]  worker_thread (kernel/workqueue.c:3340 kernel/workqueue.c:3427)
[    2.864995]  ? rescuer_thread (kernel/workqueue.c:3373)
[    2.865025]  kthread (kernel/kthread.c:463)
[    2.865056]  ? kthreads_online_cpu (kernel/kthread.c:412)
[    2.865095]  ? kthreads_online_cpu (kernel/kthread.c:412)
[    2.865134]  ret_from_fork (arch/x86/kernel/process.c:164)
[    2.865171]  ? kthreads_online_cpu (kernel/kthread.c:412)
[    2.865213]  ret_from_fork_asm (arch/x86/entry/entry_64.S:255)
| [   13.816710] ------------[ cut here ]------------
| [   13.816863] kernel BUG at net/core/net-sysfs.c:2246!
| [   13.816955] Oops: invalid opcode: 0000 [#1] SMP
| [   13.817078] Tainted: [W]=WARN
[   13.817108] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   13.817156] RIP: 0010:netdev_release (net/core/net-sysfs.c:2246 net/core/net-sysfs.c:2242)
[   13.817203] Code: fa 0f 1f 44 00 00 80 7f d8 04 75 1d 55 48 8d af a8 fa ff ff 48 8b bf e0 fb ff ff e8 ed d7 a4 ff 48 89 ef 5d e9 a4 de a4 ff 90 <0f> 0b 90 f3 0f 1e fa 0f 1f 44 00 00 55 48 89 f5 48 8d 97 c8 fb ff
All code
========
   0:	fa                   	cli
   1:	0f 1f 44 00 00       	nopl   0x0(%rax,%rax,1)
   6:	80 7f d8 04          	cmpb   $0x4,-0x28(%rdi)
   a:	75 1d                	jne    0x29
   c:	55                   	push   %rbp
   d:	48 8d af a8 fa ff ff 	lea    -0x558(%rdi),%rbp
  14:	48 8b bf e0 fb ff ff 	mov    -0x420(%rdi),%rdi
  1b:	e8 ed d7 a4 ff       	call   0xffffffffffa4d80d
  20:	48 89 ef             	mov    %rbp,%rdi
  23:	5d                   	pop    %rbp
  24:	e9 a4 de a4 ff       	jmp    0xffffffffffa4decd
  29:	90                   	nop
  2a:*	0f 0b                	ud2		<-- trapping instruction
  2c:	90                   	nop
  2d:	f3 0f 1e fa          	endbr64
  31:	0f 1f 44 00 00       	nopl   0x0(%rax,%rax,1)
  36:	55                   	push   %rbp
  37:	48 89 f5             	mov    %rsi,%rbp
  3a:	48                   	rex.W
  3b:	8d                   	.byte 0x8d
  3c:	97                   	xchg   %eax,%edi
  3d:	c8                   	.byte 0xc8
  3e:	fb                   	sti
  3f:	ff                   	.byte 0xff

Code starting with the faulting instruction
===========================================
   0:	0f 0b                	ud2
   2:	90                   	nop
   3:	f3 0f 1e fa          	endbr64
   7:	0f 1f 44 00 00       	nopl   0x0(%rax,%rax,1)
   c:	55                   	push   %rbp
   d:	48 89 f5             	mov    %rsi,%rbp
  10:	48                   	rex.W
  11:	8d                   	.byte 0x8d
  12:	97                   	xchg   %eax,%edi
  13:	c8                   	.byte 0xc8
  14:	fb                   	sti
  15:	ff                   	.byte 0xff
[   13.817329] RSP: 0018:ffffbb660029bbf0 EFLAGS: 00010297
[   13.817367] RAX: ffffffff9cf51ca0 RBX: 00000000ffffffff RCX: 0000000000000002
[   13.817429] RDX: 0000000000000006 RSI: ffffffff9cd58ea4 RDI: ffff97f2013c4558
[   13.817490] RBP: ffff97f2013c4558 R08: 0000000000000010 R09: 00000000000000fa
[   13.817544] R10: 0000000000000400 R11: 0000000000000100 R12: ffff97f201ae8800
[   13.817599] R13: ffffffff9d2b2ea0 R14: ffff97f201050790 R15: ffff97f2013c4000
[   13.817661] FS:  00007f1a5addcb80(0000) GS:ffff97f2a0891000(0000) knlGS:0000000000000000
[   13.817717] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   13.817767] CR2: 000055de067f02f8 CR3: 0000000013456004 CR4: 0000000000772ef0
[   13.817823] PKRU: 55555554
[   13.817845] Call Trace:
[   13.817871]  <TASK>
[   13.817891]  device_release (drivers/base/core.c:2569)
[   13.817932]  kobject_put (lib/kobject.c:693 lib/kobject.c:720 ./include/linux/kref.h:65 lib/kobject.c:737)
[   13.817967]  netdev_run_todo (./include/linux/list.h:381 net/core/dev.c:11670)
[   13.817999] nsim_destroy (drivers/net/netdevsim/netdevsim.h:396 drivers/net/netdevsim/netdev.c:1186) netdevsim
[   13.818045] __nsim_dev_port_del (drivers/net/netdevsim/dev.c:441 drivers/net/netdevsim/dev.c:1474) netdevsim
[   13.818087] nsim_dev_reload_destroy (drivers/net/netdevsim/dev.c:1483 drivers/net/netdevsim/dev.c:1707) netdevsim
[   13.818126] nsim_drv_remove (drivers/net/netdevsim/dev.c:1724) netdevsim
[   13.818164]  device_release_driver_internal (drivers/base/dd.c:1276 drivers/base/dd.c:1297)
[   13.818208]  bus_remove_device (./include/linux/kobject.h:193 (discriminator 3) drivers/base/base.h:73 (discriminator 3) drivers/base/bus.c:586 (discriminator 3))
[   13.818239]  device_del (drivers/base/core.c:3879)
[   13.818271]  device_unregister (drivers/base/core.c:3796 drivers/base/core.c:3920)
[   13.818301] del_device_store (drivers/net/netdevsim/bus.c:248) netdevsim
[   13.818341]  kernfs_fop_write_iter (fs/kernfs/file.c:88 fs/kernfs/file.c:356)
[   13.818386]  vfs_write (fs/read_write.c:594 fs/read_write.c:686)
[   13.818424]  ksys_write (fs/read_write.c:738)
[   13.818454]  do_syscall_64 (arch/x86/entry/syscall_64.c:63 arch/x86/entry/syscall_64.c:94)
[   13.818491]  entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)
[   13.818534] RIP: 0033:0x7f1a5aedd257
[   13.818565] Code: 0f 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b7 0f 1f 00 f3 0f 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 51 c3 48 83 ec 28 48 89 54 24 18 48 89 74 24
All code
========
   0:	0f 00                	(bad)
   2:	f7 d8                	neg    %eax
   4:	64 89 02             	mov    %eax,%fs:(%rdx)
   7:	48 c7 c0 ff ff ff ff 	mov    $0xffffffffffffffff,%rax
   e:	eb b7                	jmp    0xffffffffffffffc7
  10:	0f 1f 00             	nopl   (%rax)
  13:	f3 0f 1e fa          	endbr64
  17:	64 8b 04 25 18 00 00 	mov    %fs:0x18,%eax
  1e:	00 
  1f:	85 c0                	test   %eax,%eax
  21:	75 10                	jne    0x33
  23:	b8 01 00 00 00       	mov    $0x1,%eax
  28:	0f 05                	syscall
  2a:*	48 3d 00 f0 ff ff    	cmp    $0xfffffffffffff000,%rax		<-- trapping instruction
  30:	77 51                	ja     0x83
  32:	c3                   	ret
  33:	48 83 ec 28          	sub    $0x28,%rsp
  37:	48 89 54 24 18       	mov    %rdx,0x18(%rsp)
  3c:	48                   	rex.W
  3d:	89                   	.byte 0x89
  3e:	74 24                	je     0x64

Code starting with the faulting instruction
===========================================
   0:	48 3d 00 f0 ff ff    	cmp    $0xfffffffffffff000,%rax
   6:	77 51                	ja     0x59
   8:	c3                   	ret
   9:	48 83 ec 28          	sub    $0x28,%rsp
   d:	48 89 54 24 18       	mov    %rdx,0x18(%rsp)
  12:	48                   	rex.W
  13:	89                   	.byte 0x89
  14:	74 24                	je     0x3a
[   13.818683] RSP: 002b:00007fffbfa3c188 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
[   13.818746] RAX: ffffffffffffffda RBX: 00007f1a5afd9780 RCX: 00007f1a5aedd257
[   13.818800] RDX: 0000000000000005 RSI: 000055de067ef2f0 RDI: 0000000000000001
[   13.818855] RBP: 0000000000000005 R08: 0000000000000004 R09: 0000000000000077
[   13.818909] R10: 0000000000000063 R11: 0000000000000246 R12: 0000000000000005


Finger prints:
refcount_warn_saturate:netdev_run_todo:ops_undo_list:cleanup_net:process_one_work
netdev_release:device_release:kobject_put:netdev_run_todo:nsim_destroy