======================================
| [   18.767941][   T72] ==================================================================
| [   18.768235][   T72] 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)
| [   18.768514][   T72] Write of size 8 at addr 0000000000000000 by task kworker/u16:1/72
| [   18.768773][   T72]
[   18.768891][   T72] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   18.768895][   T72] Workqueue: netns cleanup_net
[   18.768916][   T72] Call Trace:
[   18.768919][   T72]  <TASK>
[   18.768922][   T72]  dump_stack_lvl (lib/dump_stack.c:123)
[   18.768938][   T72]  ? try_to_grab_pending (./arch/x86/include/asm/bitops.h:136 ./include/asm-generic/bitops/instrumented-atomic.h:72 kernel/workqueue.c:2072)
[   18.768943][   T72]  kasan_report (mm/kasan/report.c:597)
[   18.768956][   T72]  ? try_to_grab_pending (./arch/x86/include/asm/bitops.h:136 ./include/asm-generic/bitops/instrumented-atomic.h:72 kernel/workqueue.c:2072)
[   18.768962][   T72]  kasan_check_range (mm/kasan/generic.c:194 mm/kasan/generic.c:200)
[   18.768966][   T72]  try_to_grab_pending (./arch/x86/include/asm/bitops.h:136 ./include/asm-generic/bitops/instrumented-atomic.h:72 kernel/workqueue.c:2072)
[   18.768970][   T72]  __cancel_work (kernel/workqueue.c:2161 kernel/workqueue.c:4364)
[   18.768974][   T72]  ? enable_delayed_work (kernel/workqueue.c:4359)
[   18.768980][   T72]  ? queue_delayed_work_on (kernel/workqueue.c:2565 (discriminator 1))
[   18.768985][   T72]  __cancel_work_sync (kernel/workqueue.c:4383)
[   18.768989][   T72]  __dev_close_many (net/core/dev.c:1879 (discriminator 2) net/core/dev.c:1932 (discriminator 2))
[   18.768996][   T72]  ? netdev_notify_peers (net/core/dev.c:1891)
[   18.768999][   T72]  ? netif_close_many (net/core/dev.c:1959)
[   18.769003][   T72]  netif_close_many (net/core/dev.c:1959)
[   18.769007][   T72]  ? __mutex_handoff (kernel/locking/mutex.c:88)
[   18.769015][   T72]  ? __dev_close_many (net/core/dev.c:1949)
[   18.769019][   T72]  ? netif_close_many_and_unlock (net/core/dev.c:12476)
[   18.769022][   T72]  ? trace_contention_end (./include/trace/events/lock.h:122 (discriminator 21))
[   18.769026][   T72]  unregister_netdevice_many_notify (net/core/dev.c:12545)
[   18.769030][   T72]  ? default_device_exit_batch (net/core/dev.c:13215)
[   18.769035][   T72]  ? 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)
[   18.769038][   T72]  ? dev_ingress_queue_create (net/core/dev.c:12499)
[   18.769041][   T72]  ? rtnl_is_locked (net/core/rtnetlink.c:169)
[   18.769046][   T72]  ? unregister_netdevice_queue (net/core/dev.c:12442)
[   18.769049][   T72]  ? unregister_netdevice_many (net/core/dev.c:12441)
[   18.769053][   T72]  ? unregister_netdevice_many (net/core/dev.c:12441)
[   18.769059][   T72]  default_device_exit_batch (net/core/dev.c:13229)
[   18.769063][   T72]  ? unregister_netdev (net/core/dev.c:13204)
[   18.769069][   T72]  ops_undo_list (net/core/net_namespace.c:251)
[   18.769074][   T72]  ? rtnl_net_dumpid_one (net/core/net_namespace.c:223)
[   18.769078][   T72]  ? cleanup_net (./include/linux/list.h:191 net/core/net_namespace.c:693)
[   18.769084][   T72]  cleanup_net (net/core/net_namespace.c:698)
[   18.769088][   T72]  ? net_passive_dec (net/core/net_namespace.c:660)
[   18.769093][   T72]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   18.769103][   T72]  process_one_work (kernel/workqueue.c:3268)
[   18.769110][   T72]  ? pwq_dec_nr_in_flight (kernel/workqueue.c:3165)
[   18.769116][   T72]  ? assign_work (kernel/workqueue.c:1206)
[   18.769120][   T72]  worker_thread (kernel/workqueue.c:3340 kernel/workqueue.c:3427)
[   18.769126][   T72]  ? rescuer_thread (kernel/workqueue.c:3373)
[   18.769130][   T72]  kthread (kernel/kthread.c:463)
[   18.769136][   T72]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   18.769139][   T72]  ? ret_from_fork (arch/x86/kernel/process.c:157)
[   18.769149][   T72]  ? __lock_release (kernel/locking/lockdep.c:5536)
[   18.769152][   T72]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   18.769156][   T72]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   18.769159][   T72]  ret_from_fork (arch/x86/kernel/process.c:164)
[   18.769162][   T72]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   18.769165][   T72]  ret_from_fork_asm (arch/x86/entry/entry_64.S:255)
| [   18.779665][   T72] #PF: error_code(0x0002) - not-present page
| [   18.779869][   T72] PGD 0 P4D 0
| [   18.780003][   T72] Oops: Oops: 0002 [#1] SMP KASAN
| [   18.780641][   T72] Tainted: [B]=BAD_PAGE
[   18.780770][   T72] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   18.781082][   T72] Workqueue: netns cleanup_net
[   18.781259][   T72] 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)
[   18.781476][   T72] 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
[   18.782165][   T72] RSP: 0018:ffffc900004d7680 EFLAGS: 00010046
[   18.782372][   T72] RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff93e49b8a
[   18.782722][   T72] RDX: fffffbfff316cacd RSI: 0000000000000008 RDI: ffffffff98b65660
[   18.782974][   T72] RBP: ffffc900004d76e8 R08: 0000000000000001 R09: fffffbfff316cacc
[   18.783324][   T72] R10: ffffffff98b65667 R11: ffffc900004d7140 R12: 0000000000000000
[   18.783569][   T72] R13: 0000000000000282 R14: ffff88800ab6c000 R15: dffffc0000000000
[   18.783818][   T72] FS:  0000000000000000(0000) GS:ffff8880d4587000(0000) knlGS:0000000000000000
[   18.784116][   T72] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   18.784319][   T72] CR2: 0000000000000000 CR3: 0000000032149002 CR4: 0000000000772ef0
[   18.784565][   T72] PKRU: 55555554
[   18.784786][   T72] Call Trace:
[   18.784912][   T72]  <TASK>
[   18.785003][   T72]  __cancel_work (kernel/workqueue.c:2161 kernel/workqueue.c:4364)
[   18.785170][   T72]  ? enable_delayed_work (kernel/workqueue.c:4359)
[   18.785339][   T72]  ? queue_delayed_work_on (kernel/workqueue.c:2565 (discriminator 1))
[   18.785598][   T72]  __cancel_work_sync (kernel/workqueue.c:4383)
[   18.785760][   T72]  __dev_close_many (net/core/dev.c:1879 (discriminator 2) net/core/dev.c:1932 (discriminator 2))
[   18.785937][   T72]  ? netdev_notify_peers (net/core/dev.c:1891)
[   18.786105][   T72]  ? netif_close_many (net/core/dev.c:1959)
[   18.786364][   T72]  netif_close_many (net/core/dev.c:1959)
[   18.786525][   T72]  ? __mutex_handoff (kernel/locking/mutex.c:88)
[   18.786690][   T72]  ? __dev_close_many (net/core/dev.c:1949)
[   18.786860][   T72]  ? netif_close_many_and_unlock (net/core/dev.c:12476)
[   18.787167][   T72]  ? trace_contention_end (./include/trace/events/lock.h:122 (discriminator 21))
[   18.787341][   T72]  unregister_netdevice_many_notify (net/core/dev.c:12545)
[   18.787545][   T72]  ? default_device_exit_batch (net/core/dev.c:13215)
[   18.787805][   T72]  ? 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)
[   18.787974][   T72]  ? dev_ingress_queue_create (net/core/dev.c:12499)
[   18.788142][   T72]  ? rtnl_is_locked (net/core/rtnetlink.c:169)
[   18.788305][   T72]  ? unregister_netdevice_queue (net/core/dev.c:12442)
[   18.788599][   T72]  ? unregister_netdevice_many (net/core/dev.c:12441)
[   18.788761][   T72]  ? unregister_netdevice_many (net/core/dev.c:12441)
[   18.788942][   T72]  default_device_exit_batch (net/core/dev.c:13229)
[   18.789114][   T72]  ? unregister_netdev (net/core/dev.c:13204)
[   18.789374][   T72]  ops_undo_list (net/core/net_namespace.c:251)
[   18.789538][   T72]  ? rtnl_net_dumpid_one (net/core/net_namespace.c:223)
[   18.789704][   T72]  ? cleanup_net (./include/linux/list.h:191 net/core/net_namespace.c:693)
[   18.789873][   T72]  cleanup_net (net/core/net_namespace.c:698)
[   18.790052][   T72]  ? net_passive_dec (net/core/net_namespace.c:660)
[   18.790221][   T72]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   18.790422][   T72]  process_one_work (kernel/workqueue.c:3268)
[   18.790605][   T72]  ? pwq_dec_nr_in_flight (kernel/workqueue.c:3165)
[   18.790873][   T72]  ? assign_work (kernel/workqueue.c:1206)
[   18.791041][   T72]  worker_thread (kernel/workqueue.c:3340 kernel/workqueue.c:3427)
[   18.791204][   T72]  ? rescuer_thread (kernel/workqueue.c:3373)
[   18.791366][   T72]  kthread (kernel/kthread.c:463)
[   18.791599][   T72]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   18.791760][   T72]  ? ret_from_fork (arch/x86/kernel/process.c:157)
[   18.791931][   T72]  ? __lock_release (kernel/locking/lockdep.c:5536)
[   18.792095][   T72]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   18.792350][   T72]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   18.792513][   T72]  ret_from_fork (arch/x86/kernel/process.c:164)
[   18.792677][   T72]  ? 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