======================================
| [   18.391166][   T69] ==================================================================
| [   18.391452][   T69] BUG: KASAN: null-ptr-deref in try_to_grab_pending (./arch/x86/include/asm/bitops.h:136 ./include/asm-generic/bitops/instrumented-atomic.h:72 kernel/workqueue.c:2072)
| [   18.391719][   T69] Write of size 8 at addr 0000000000000000 by task kworker/u16:1/69
| [   18.391960][   T69]
[   18.392052][   T69] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   18.392057][   T69] Workqueue: netns cleanup_net
[   18.392070][   T69] Call Trace:
[   18.392073][   T69]  <TASK>
[   18.392076][   T69]  dump_stack_lvl (lib/dump_stack.c:123)
[   18.392084][   T69]  ? try_to_grab_pending (./arch/x86/include/asm/bitops.h:136 ./include/asm-generic/bitops/instrumented-atomic.h:72 kernel/workqueue.c:2072)
[   18.392087][   T69]  kasan_report (mm/kasan/report.c:597)
[   18.392102][   T69]  ? try_to_grab_pending (./arch/x86/include/asm/bitops.h:136 ./include/asm-generic/bitops/instrumented-atomic.h:72 kernel/workqueue.c:2072)
[   18.392107][   T69]  kasan_check_range (mm/kasan/generic.c:194 mm/kasan/generic.c:200)
[   18.392111][   T69]  try_to_grab_pending (./arch/x86/include/asm/bitops.h:136 ./include/asm-generic/bitops/instrumented-atomic.h:72 kernel/workqueue.c:2072)
[   18.392114][   T69]  ? netif_close_many (net/core/dev.c:1959)
[   18.392120][   T69]  __cancel_work (kernel/workqueue.c:2161 kernel/workqueue.c:4364)
[   18.392124][   T69]  ? enable_delayed_work (kernel/workqueue.c:4359)
[   18.392129][   T69]  ? queue_delayed_work_on (kernel/workqueue.c:2565 (discriminator 1))
[   18.392134][   T69]  __cancel_work_sync (kernel/workqueue.c:4383)
[   18.392139][   T69]  __dev_close_many (net/core/dev.c:1879 (discriminator 2) net/core/dev.c:1932 (discriminator 2))
[   18.392142][   T69]  ? netdev_notify_peers (net/core/dev.c:1891)
[   18.392146][   T69]  ? netif_close_many (net/core/dev.c:1959)
[   18.392150][   T69]  netif_close_many (net/core/dev.c:1959)
[   18.392153][   T69]  ? __mutex_handoff (kernel/locking/mutex.c:88)
[   18.392163][   T69]  ? __dev_close_many (net/core/dev.c:1949)
[   18.392166][   T69]  ? netif_close_many_and_unlock (net/core/dev.c:12476)
[   18.392169][   T69]  ? trace_contention_end (./include/trace/events/lock.h:122 (discriminator 21))
[   18.392173][   T69]  unregister_netdevice_many_notify (net/core/dev.c:12545)
[   18.392178][   T69]  ? default_device_exit_batch (net/core/dev.c:13215)
[   18.392182][   T69]  ? mutex_is_locked (./arch/x86/include/asm/atomic64_64.h:15 ./include/linux/atomic/atomic-arch-fallback.h:2583 ./include/linux/atomic/atomic-long.h:38 ./include/linux/atomic/atomic-instrumented.h:3189 kernel/locking/mutex.h:47 kernel/locking/mutex.c:67)
[   18.392186][   T69]  ? dev_ingress_queue_create (net/core/dev.c:12499)
[   18.392189][   T69]  ? rtnl_is_locked (net/core/rtnetlink.c:169)
[   18.392193][   T69]  ? unregister_netdevice_queue (net/core/dev.c:12442)
[   18.392196][   T69]  ? unregister_netdevice_many (net/core/dev.c:12441)
[   18.392200][   T69]  ? unregister_netdevice_many (net/core/dev.c:12441)
[   18.392206][   T69]  default_device_exit_batch (net/core/dev.c:13229)
[   18.392209][   T69]  ? unregister_netdev (net/core/dev.c:13204)
[   18.392215][   T69]  ops_undo_list (net/core/net_namespace.c:251)
[   18.392221][   T69]  ? rtnl_net_dumpid_one (net/core/net_namespace.c:223)
[   18.392224][   T69]  ? cleanup_net (./include/linux/list.h:191 net/core/net_namespace.c:693)
[   18.392230][   T69]  cleanup_net (net/core/net_namespace.c:698)
[   18.392235][   T69]  ? net_passive_dec (net/core/net_namespace.c:660)
[   18.392239][   T69]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   18.392247][   T69]  process_one_work (kernel/workqueue.c:3268)
[   18.392254][   T69]  ? pwq_dec_nr_in_flight (kernel/workqueue.c:3165)
[   18.392260][   T69]  ? assign_work (kernel/workqueue.c:1206)
[   18.392264][   T69]  worker_thread (kernel/workqueue.c:3340 kernel/workqueue.c:3427)
[   18.392270][   T69]  ? rescuer_thread (kernel/workqueue.c:3373)
[   18.392274][   T69]  kthread (kernel/kthread.c:463)
[   18.392282][   T69]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   18.392284][   T69]  ? ret_from_fork (arch/x86/kernel/process.c:157)
[   18.392290][   T69]  ? __lock_release (kernel/locking/lockdep.c:5536)
[   18.392294][   T69]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   18.392297][   T69]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   18.392301][   T69]  ret_from_fork (arch/x86/kernel/process.c:164)
[   18.392303][   T69]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   18.392306][   T69]  ret_from_fork_asm (arch/x86/entry/entry_64.S:255)
| [   18.402031][   T69] #PF: error_code(0x0002) - not-present page
| [   18.402236][   T69] PGD 0 P4D 0
| [   18.402363][   T69] Oops: Oops: 0002 [#1] SMP KASAN
| [   18.402895][   T69] Tainted: [B]=BAD_PAGE
[   18.403016][   T69] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   18.403220][   T69] Workqueue: netns cleanup_net
[   18.403391][   T69] RIP: 0010:try_to_grab_pending (./arch/x86/include/asm/bitops.h:136 ./include/asm-generic/bitops/instrumented-atomic.h:72 kernel/workqueue.c:2072)
[   18.403604][   T69] Code: 00 41 89 c0 b8 01 00 00 00 45 85 c0 74 0f 48 83 c4 10 5b 5d 41 5c 41 5d 41 5e 41 5f c3 be 08 00 00 00 48 89 df e8 1f 93 82 00 <f0> 48 0f ba 2b 00 72 11 48 83 c4 10 31 c0 5b 5d 41 5c 41 5d 41 5e
All code
========
   0:	00 41 89             	add    %al,-0x77(%rcx)
   3:	c0 b8 01 00 00 00 45 	sarb   $0x45,0x1(%rax)
   a:	85 c0                	test   %eax,%eax
   c:	74 0f                	je     0x1d
   e:	48 83 c4 10          	add    $0x10,%rsp
  12:	5b                   	pop    %rbx
  13:	5d                   	pop    %rbp
  14:	41 5c                	pop    %r12
  16:	41 5d                	pop    %r13
  18:	41 5e                	pop    %r14
  1a:	41 5f                	pop    %r15
  1c:	c3                   	ret
  1d:	be 08 00 00 00       	mov    $0x8,%esi
  22:	48 89 df             	mov    %rbx,%rdi
  25:	e8 1f 93 82 00       	call   0x829349
  2a:*	f0 48 0f ba 2b 00    	lock btsq $0x0,(%rbx)		<-- trapping instruction
  30:	72 11                	jb     0x43
  32:	48 83 c4 10          	add    $0x10,%rsp
  36:	31 c0                	xor    %eax,%eax
  38:	5b                   	pop    %rbx
  39:	5d                   	pop    %rbp
  3a:	41 5c                	pop    %r12
  3c:	41 5d                	pop    %r13
  3e:	41 5e                	pop    %r14

Code starting with the faulting instruction
===========================================
   0:	f0 48 0f ba 2b 00    	lock btsq $0x0,(%rbx)
   6:	72 11                	jb     0x19
   8:	48 83 c4 10          	add    $0x10,%rsp
   c:	31 c0                	xor    %eax,%eax
   e:	5b                   	pop    %rbx
   f:	5d                   	pop    %rbp
  10:	41 5c                	pop    %r12
  12:	41 5d                	pop    %r13
  14:	41 5e                	pop    %r14
[   18.404171][   T69] RSP: 0018:ffffc900004a7680 EFLAGS: 00010046
[   18.404376][   T69] RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff84649b8a
[   18.404623][   T69] RDX: fffffbfff126cacd RSI: 0000000000000008 RDI: ffffffff89365660
[   18.404864][   T69] RBP: ffffc900004a76e8 R08: 0000000000000001 R09: fffffbfff126cacc
[   18.405104][   T69] R10: ffffffff89365667 R11: ffffc900004a7140 R12: 0000000000000000
[   18.405345][   T69] R13: 0000000000000282 R14: ffff88800eb4c000 R15: dffffc0000000000
[   18.405591][   T69] FS:  0000000000000000(0000) GS:ffff8880dd807000(0000) knlGS:0000000000000000
[   18.405867][   T69] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   18.406068][   T69] CR2: 0000000000000000 CR3: 0000000073949005 CR4: 0000000000772ef0
[   18.406309][   T69] PKRU: 55555554
[   18.406431][   T69] Call Trace:
[   18.406559][   T69]  <TASK>
[   18.406642][   T69]  ? netif_close_many (net/core/dev.c:1959)
[   18.406804][   T69]  __cancel_work (kernel/workqueue.c:2161 kernel/workqueue.c:4364)
[   18.406964][   T69]  ? enable_delayed_work (kernel/workqueue.c:4359)
[   18.407133][   T69]  ? queue_delayed_work_on (kernel/workqueue.c:2565 (discriminator 1))
[   18.407293][   T69]  __cancel_work_sync (kernel/workqueue.c:4383)
[   18.407461][   T69]  __dev_close_many (net/core/dev.c:1879 (discriminator 2) net/core/dev.c:1932 (discriminator 2))
[   18.407625][   T69]  ? netdev_notify_peers (net/core/dev.c:1891)
[   18.407784][   T69]  ? netif_close_many (net/core/dev.c:1959)
[   18.407946][   T69]  netif_close_many (net/core/dev.c:1959)
[   18.408106][   T69]  ? __mutex_handoff (kernel/locking/mutex.c:88)
[   18.408266][   T69]  ? __dev_close_many (net/core/dev.c:1949)
[   18.408429][   T69]  ? netif_close_many_and_unlock (net/core/dev.c:12476)
[   18.408632][   T69]  ? trace_contention_end (./include/trace/events/lock.h:122 (discriminator 21))
[   18.408796][   T69]  unregister_netdevice_many_notify (net/core/dev.c:12545)
[   18.408991][   T69]  ? default_device_exit_batch (net/core/dev.c:13215)
[   18.409158][   T69]  ? mutex_is_locked (./arch/x86/include/asm/atomic64_64.h:15 ./include/linux/atomic/atomic-arch-fallback.h:2583 ./include/linux/atomic/atomic-long.h:38 ./include/linux/atomic/atomic-instrumented.h:3189 kernel/locking/mutex.h:47 kernel/locking/mutex.c:67)
[   18.409316][   T69]  ? dev_ingress_queue_create (net/core/dev.c:12499)
[   18.409480][   T69]  ? rtnl_is_locked (net/core/rtnetlink.c:169)
[   18.409634][   T69]  ? unregister_netdevice_queue (net/core/dev.c:12442)
[   18.409832][   T69]  ? unregister_netdevice_many (net/core/dev.c:12441)
[   18.409989][   T69]  ? unregister_netdevice_many (net/core/dev.c:12441)
[   18.410161][   T69]  default_device_exit_batch (net/core/dev.c:13229)
[   18.410323][   T69]  ? unregister_netdev (net/core/dev.c:13204)
[   18.410488][   T69]  ops_undo_list (net/core/net_namespace.c:251)
[   18.410650][   T69]  ? rtnl_net_dumpid_one (net/core/net_namespace.c:223)
[   18.410808][   T69]  ? cleanup_net (./include/linux/list.h:191 net/core/net_namespace.c:693)
[   18.410971][   T69]  cleanup_net (net/core/net_namespace.c:698)
[   18.411141][   T69]  ? net_passive_dec (net/core/net_namespace.c:660)
[   18.411299][   T69]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   18.411471][   T69]  process_one_work (kernel/workqueue.c:3268)
[   18.411633][   T69]  ? pwq_dec_nr_in_flight (kernel/workqueue.c:3165)
[   18.411792][   T69]  ? assign_work (kernel/workqueue.c:1206)
[   18.411950][   T69]  worker_thread (kernel/workqueue.c:3340 kernel/workqueue.c:3427)
[   18.412112][   T69]  ? rescuer_thread (kernel/workqueue.c:3373)
[   18.412272][   T69]  kthread (kernel/kthread.c:463)
[   18.412394][   T69]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   18.412556][   T69]  ? ret_from_fork (arch/x86/kernel/process.c:157)
[   18.412718][   T69]  ? __lock_release (kernel/locking/lockdep.c:5536)
[   18.412876][   T69]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   18.413038][   T69]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   18.413292][   T69]  ret_from_fork (arch/x86/kernel/process.c:164)
[   18.413458][   T69]  ? kthread_is_per_cpu (kernel/kthread.c:412)


Finger prints:
kasan_report:kasan_check_range:try_to_grab_pending:__cancel_work:__cancel_work_sync
try_to_grab_pending:__cancel_work:__cancel_work_sync:__dev_close_many:netif_close_many