======================================
| [   18.323367][   T71] ==================================================================
| [   18.323752][   T71] 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)
| [   18.324079][   T71] Write of size 8 at addr 0000000000000000 by task kworker/u16:1/71
| [   18.324371][   T71]
[   18.324492][   T71] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   18.324498][   T71] Workqueue: netns cleanup_net
[   18.324514][   T71] Call Trace:
[   18.324520][   T71]  <TASK>
[   18.324523][   T71]  dump_stack_lvl (lib/dump_stack.c:123)
[   18.324533][   T71]  ? try_to_grab_pending (./arch/x86/include/asm/bitops.h:136 ./include/asm-generic/bitops/instrumented-atomic.h:72 kernel/workqueue.c:2072)
[   18.324537][   T71]  kasan_report (mm/kasan/report.c:597)
[   18.324558][   T71]  ? try_to_grab_pending (./arch/x86/include/asm/bitops.h:136 ./include/asm-generic/bitops/instrumented-atomic.h:72 kernel/workqueue.c:2072)
[   18.324566][   T71]  kasan_check_range (mm/kasan/generic.c:194 mm/kasan/generic.c:200)
[   18.324570][   T71]  try_to_grab_pending (./arch/x86/include/asm/bitops.h:136 ./include/asm-generic/bitops/instrumented-atomic.h:72 kernel/workqueue.c:2072)
[   18.324575][   T71]  __cancel_work (kernel/workqueue.c:2161 kernel/workqueue.c:4364)
[   18.324578][   T71]  ? enable_delayed_work (kernel/workqueue.c:4359)
[   18.324585][   T71]  __cancel_work_sync (kernel/workqueue.c:4383)
[   18.324590][   T71]  __dev_close_many (net/core/dev.c:1879 (discriminator 2) net/core/dev.c:1932 (discriminator 2))
[   18.324597][   T71]  ? netdev_notify_peers (net/core/dev.c:1891)
[   18.324600][   T71]  ? netif_close_many (net/core/dev.c:1959)
[   18.324605][   T71]  netif_close_many (net/core/dev.c:1959)
[   18.324608][   T71]  ? __mutex_handoff (kernel/locking/mutex.c:88)
[   18.324616][   T71]  ? __dev_close_many (net/core/dev.c:1949)
[   18.324620][   T71]  ? netif_close_many_and_unlock (net/core/dev.c:12476)
[   18.324623][   T71]  ? trace_contention_end (./include/trace/events/lock.h:122 (discriminator 21))
[   18.324627][   T71]  unregister_netdevice_many_notify (net/core/dev.c:12545)
[   18.324631][   T71]  ? default_device_exit_batch (net/core/dev.c:13215)
[   18.324636][   T71]  ? 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)
[   18.324640][   T71]  ? dev_ingress_queue_create (net/core/dev.c:12499)
[   18.324643][   T71]  ? rtnl_is_locked (net/core/rtnetlink.c:169)
[   18.324649][   T71]  ? unregister_netdevice_queue (net/core/dev.c:12442)
[   18.324652][   T71]  ? unregister_netdevice_many (net/core/dev.c:12441)
[   18.324656][   T71]  ? unregister_netdevice_many (net/core/dev.c:12441)
[   18.324662][   T71]  default_device_exit_batch (net/core/dev.c:13229)
[   18.324665][   T71]  ? unregister_netdev (net/core/dev.c:13204)
[   18.324672][   T71]  ops_undo_list (net/core/net_namespace.c:251)
[   18.324677][   T71]  ? rtnl_net_dumpid_one (net/core/net_namespace.c:223)
[   18.324680][   T71]  ? cleanup_net (./include/linux/list.h:191 net/core/net_namespace.c:693)
[   18.324687][   T71]  cleanup_net (net/core/net_namespace.c:698)
[   18.324691][   T71]  ? net_passive_dec (net/core/net_namespace.c:660)
[   18.324696][   T71]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   18.324705][   T71]  process_one_work (kernel/workqueue.c:3268)
[   18.324712][   T71]  ? pwq_dec_nr_in_flight (kernel/workqueue.c:3165)
[   18.324717][   T71]  ? assign_work (kernel/workqueue.c:1206)
[   18.324722][   T71]  worker_thread (kernel/workqueue.c:3340 kernel/workqueue.c:3427)
[   18.324728][   T71]  ? rescuer_thread (kernel/workqueue.c:3373)
[   18.324731][   T71]  kthread (kernel/kthread.c:463)
[   18.324740][   T71]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   18.324742][   T71]  ? ret_from_fork (arch/x86/kernel/process.c:157)
[   18.324751][   T71]  ? __lock_release (kernel/locking/lockdep.c:5536)
[   18.324755][   T71]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   18.324758][   T71]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   18.324762][   T71]  ret_from_fork (arch/x86/kernel/process.c:164)
[   18.324764][   T71]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   18.324767][   T71]  ret_from_fork_asm (arch/x86/entry/entry_64.S:255)
| [   18.336335][   T71] #PF: error_code(0x0002) - not-present page
| [   18.336588][   T71] PGD 0 P4D 0
| [   18.336735][   T71] Oops: Oops: 0002 [#1] SMP KASAN
| [   18.337374][   T71] Tainted: [B]=BAD_PAGE
[   18.337529][   T71] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   18.337777][   T71] Workqueue: netns cleanup_net
[   18.337990][   T71] 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)
[   18.338237][   T71] 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
[   18.338925][   T71] RSP: 0018:ffffc900004c7680 EFLAGS: 00010046
[   18.339165][   T71] RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffffa8849b8a
[   18.339568][   T71] RDX: fffffbfff5aacacd RSI: 0000000000000008 RDI: ffffffffad565660
[   18.339854][   T71] RBP: ffffc900004c76e8 R08: 0000000000000001 R09: fffffbfff5aacacc
[   18.340234][   T71] R10: ffffffffad565667 R11: ffffc900004c7140 R12: 0000000000000000
[   18.340534][   T71] R13: 0000000000000282 R14: ffff888005f91000 R15: dffffc0000000000
[   18.340822][   T71] FS:  0000000000000000(0000) GS:ffff8880bfc07000(0000) knlGS:0000000000000000
[   18.341157][   T71] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   18.341406][   T71] CR2: 0000000000000000 CR3: 000000000cd1b006 CR4: 0000000000772ef0
[   18.341707][   T71] PKRU: 55555554
[   18.341863][   T71] Call Trace:
[   18.342025][   T71]  <TASK>
[   18.342123][   T71]  __cancel_work (kernel/workqueue.c:2161 kernel/workqueue.c:4364)
[   18.342428][   T71]  ? enable_delayed_work (kernel/workqueue.c:4359)
[   18.342687][   T71]  __cancel_work_sync (kernel/workqueue.c:4383)
[   18.342896][   T71]  __dev_close_many (net/core/dev.c:1879 (discriminator 2) net/core/dev.c:1932 (discriminator 2))
[   18.343179][   T71]  ? netdev_notify_peers (net/core/dev.c:1891)
[   18.343464][   T71]  ? netif_close_many (net/core/dev.c:1959)
[   18.343661][   T71]  netif_close_many (net/core/dev.c:1959)
[   18.343852][   T71]  ? __mutex_handoff (kernel/locking/mutex.c:88)
[   18.344043][   T71]  ? __dev_close_many (net/core/dev.c:1949)
[   18.344232][   T71]  ? netif_close_many_and_unlock (net/core/dev.c:12476)
[   18.344468][   T71]  ? trace_contention_end (./include/trace/events/lock.h:122 (discriminator 21))
[   18.344756][   T71]  unregister_netdevice_many_notify (net/core/dev.c:12545)
[   18.344997][   T71]  ? default_device_exit_batch (net/core/dev.c:13215)
[   18.345185][   T71]  ? 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)
[   18.345375][   T71]  ? dev_ingress_queue_create (net/core/dev.c:12499)
[   18.345567][   T71]  ? rtnl_is_locked (net/core/rtnetlink.c:169)
[   18.345757][   T71]  ? unregister_netdevice_queue (net/core/dev.c:12442)
[   18.345994][   T71]  ? unregister_netdevice_many (net/core/dev.c:12441)
[   18.346181][   T71]  ? unregister_netdevice_many (net/core/dev.c:12441)
[   18.346391][   T71]  default_device_exit_batch (net/core/dev.c:13229)
[   18.346586][   T71]  ? unregister_netdev (net/core/dev.c:13204)
[   18.346768][   T71]  ops_undo_list (net/core/net_namespace.c:251)
[   18.346962][   T71]  ? rtnl_net_dumpid_one (net/core/net_namespace.c:223)
[   18.347250][   T71]  ? cleanup_net (./include/linux/list.h:191 net/core/net_namespace.c:693)
[   18.347441][   T71]  cleanup_net (net/core/net_namespace.c:698)
[   18.347730][   T71]  ? net_passive_dec (net/core/net_namespace.c:660)
[   18.347925][   T71]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   18.348218][   T71]  process_one_work (kernel/workqueue.c:3268)
[   18.348412][   T71]  ? pwq_dec_nr_in_flight (kernel/workqueue.c:3165)
[   18.348606][   T71]  ? assign_work (kernel/workqueue.c:1206)
[   18.348792][   T71]  worker_thread (kernel/workqueue.c:3340 kernel/workqueue.c:3427)
[   18.348982][   T71]  ? rescuer_thread (kernel/workqueue.c:3373)
[   18.349171][   T71]  kthread (kernel/kthread.c:463)
[   18.349316][   T71]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   18.349507][   T71]  ? ret_from_fork (arch/x86/kernel/process.c:157)
[   18.349698][   T71]  ? __lock_release (kernel/locking/lockdep.c:5536)
[   18.349897][   T71]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   18.350179][   T71]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   18.350373][   T71]  ret_from_fork (arch/x86/kernel/process.c:164)
[   18.350561][   T71]  ? 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