======================================
| [   60.544504] #PF: supervisor write access in kernel mode
| [   60.544539] #PF: error_code(0x0002) - not-present page
| [   60.544575] PGD 40a4067 P4D 40a4067 PUD 5787067 PMD 0
| [   60.544623] Oops: Oops: 0002 [#1] SMP
[   60.544723] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   60.544766] Workqueue: netns cleanup_net
[   60.544815] RIP: 0010:work_grab_pending (./arch/x86/include/asm/bitops.h:136 ./include/asm-generic/bitops/instrumented-atomic.h:72 kernel/workqueue.c:2072 kernel/workqueue.c:2160)
[   60.544869] Code: 83 e6 01 41 57 41 56 4c 8d 77 20 41 55 41 54 41 89 f4 55 48 89 d5 53 48 89 fb 9c 58 fa 48 89 45 00 45 85 e4 0f 85 8a 00 00 00 <f0> 48 0f ba 2b 00 41 0f 92 c5 72 0e 5b 44 89 e8 5d 41 5c 41 5d 41
All code
========
   0:	83 e6 01             	and    $0x1,%esi
   3:	41 57                	push   %r15
   5:	41 56                	push   %r14
   7:	4c 8d 77 20          	lea    0x20(%rdi),%r14
   b:	41 55                	push   %r13
   d:	41 54                	push   %r12
   f:	41 89 f4             	mov    %esi,%r12d
  12:	55                   	push   %rbp
  13:	48 89 d5             	mov    %rdx,%rbp
  16:	53                   	push   %rbx
  17:	48 89 fb             	mov    %rdi,%rbx
  1a:	9c                   	pushf
  1b:	58                   	pop    %rax
  1c:	fa                   	cli
  1d:	48 89 45 00          	mov    %rax,0x0(%rbp)
  21:	45 85 e4             	test   %r12d,%r12d
  24:	0f 85 8a 00 00 00    	jne    0xb4
  2a:*	f0 48 0f ba 2b 00    	lock btsq $0x0,(%rbx)		<-- trapping instruction
  30:	41 0f 92 c5          	setb   %r13b
  34:	72 0e                	jb     0x44
  36:	5b                   	pop    %rbx
  37:	44 89 e8             	mov    %r13d,%eax
  3a:	5d                   	pop    %rbp
  3b:	41 5c                	pop    %r12
  3d:	41 5d                	pop    %r13
  3f:	41                   	rex.B

Code starting with the faulting instruction
===========================================
   0:	f0 48 0f ba 2b 00    	lock btsq $0x0,(%rbx)
   6:	41 0f 92 c5          	setb   %r13b
   a:	72 0e                	jb     0x1a
   c:	5b                   	pop    %rbx
   d:	44 89 e8             	mov    %r13d,%eax
  10:	5d                   	pop    %rbp
  11:	41 5c                	pop    %r12
  13:	41 5d                	pop    %r13
  15:	41                   	rex.B
[   60.544979] RSP: 0018:ffffb2dd00257b88 EFLAGS: 00010046
[   60.545014] RAX: 0000000000000246 RBX: 0000000000000000 RCX: 0000000000000004
[   60.545064] RDX: ffffb2dd00257bc0 RSI: 0000000000000000 RDI: 0000000000000000
[   60.545114] RBP: ffffb2dd00257bc0 R08: ffff964142111f73 R09: ffffffffb3071c80
[   60.545165] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
[   60.545215] R13: 0000000000000000 R14: 0000000000000020 R15: 0000000000000001
[   60.545267] FS:  0000000000000000(0000) GS:ffff9641cb491000(0000) knlGS:0000000000000000
[   60.545320] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   60.545362] CR2: 0000000000000000 CR3: 00000000043e6001 CR4: 0000000000772ef0
[   60.545413] PKRU: 55555554
[   60.545436] Call Trace:
[   60.545460]  <TASK>
[   60.545483]  __cancel_work (kernel/workqueue.c:4366)
[   60.545513]  ? linkwatch_urgent_event (net/core/link_watch.c:114)
[   60.545552]  __cancel_work_sync (kernel/workqueue.c:4381)
[   60.545580]  __dev_close_many (net/core/dev.c:1879 (discriminator 2) net/core/dev.c:1932 (discriminator 2))
[   60.545623]  __dev_change_flags (./include/linux/list.h:226 ./include/linux/list.h:237 net/core/dev.c:1945 net/core/dev.c:9924)
[   60.545657]  netif_change_flags (net/core/dev.c:9989)
[   60.545694]  dev_change_flags (./include/net/netdev_lock.h:30 ./include/net/netdev_lock.h:47 net/core/dev_api.c:69)
[   60.545722]  cycle_netdev (drivers/net/vrf.c:1052)
[   60.545758]  vrf_dellink (drivers/net/vrf.c:1671)
[   60.545789]  default_device_exit_batch (net/core/dev.c:13221 (discriminator 2))
[   60.545829]  ? mutex_lock (./arch/x86/include/asm/atomic64_64.h:101 ./include/linux/atomic/atomic-arch-fallback.h:4296 ./include/linux/atomic/atomic-long.h:1482 ./include/linux/atomic/atomic-instrumented.h:4458 kernel/locking/mutex.c:157 kernel/locking/mutex.c:273)
[   60.545865]  ops_undo_list (net/core/net_namespace.c:251)
[   60.545897]  cleanup_net (net/core/net_namespace.c:698)
[   60.545927]  process_one_work (kernel/workqueue.c:3268)
[   60.545957]  worker_thread (kernel/workqueue.c:3340 kernel/workqueue.c:3427)
[   60.545985]  ? rescuer_thread (kernel/workqueue.c:3373)
[   60.546012]  kthread (kernel/kthread.c:463)
[   60.546048]  ? kthreads_online_cpu (kernel/kthread.c:412)
[   60.546117]  ? kthreads_online_cpu (kernel/kthread.c:412)
[   60.546152]  ret_from_fork (arch/x86/kernel/process.c:164)
[   60.546193]  ? kthreads_online_cpu (kernel/kthread.c:412)


Finger prints:
work_grab_pending:__cancel_work:__cancel_work_sync:__dev_close_many:__dev_change_flags