======================================
| [   20.829307][   T69] ==================================================================
| [   20.829598][   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)
| [   20.829886][   T69] Write of size 8 at addr 0000000000000000 by task kworker/u16:1/69
| [   20.830131][   T69]
[   20.830229][   T69] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   20.830232][   T69] Workqueue: netns cleanup_net
[   20.830247][   T69] Call Trace:
[   20.830251][   T69]  <TASK>
[   20.830254][   T69]  dump_stack_lvl (lib/dump_stack.c:123)
[   20.830263][   T69]  ? try_to_grab_pending (./arch/x86/include/asm/bitops.h:136 ./include/asm-generic/bitops/instrumented-atomic.h:72 kernel/workqueue.c:2072)
[   20.830269][   T69]  kasan_report (mm/kasan/report.c:597)
[   20.830279][   T69]  ? try_to_grab_pending (./arch/x86/include/asm/bitops.h:136 ./include/asm-generic/bitops/instrumented-atomic.h:72 kernel/workqueue.c:2072)
[   20.830285][   T69]  kasan_check_range (mm/kasan/generic.c:194 mm/kasan/generic.c:200)
[   20.830289][   T69]  try_to_grab_pending (./arch/x86/include/asm/bitops.h:136 ./include/asm-generic/bitops/instrumented-atomic.h:72 kernel/workqueue.c:2072)
[   20.830294][   T69]  __cancel_work (kernel/workqueue.c:2161 kernel/workqueue.c:4364)
[   20.830297][   T69]  ? enable_delayed_work (kernel/workqueue.c:4359)
[   20.830304][   T69]  ? queue_delayed_work_on (kernel/workqueue.c:2565 (discriminator 1))
[   20.830309][   T69]  __cancel_work_sync (kernel/workqueue.c:4383)
[   20.830313][   T69]  __dev_close_many (net/core/dev.c:1879 (discriminator 2) net/core/dev.c:1932 (discriminator 2))
[   20.830319][   T69]  ? netdev_notify_peers (net/core/dev.c:1891)
[   20.830322][   T69]  ? netif_close_many (net/core/dev.c:1959)
[   20.830326][   T69]  netif_close_many (net/core/dev.c:1959)
[   20.830329][   T69]  ? __mutex_handoff (kernel/locking/mutex.c:88)
[   20.830336][   T69]  ? __dev_close_many (net/core/dev.c:1949)
[   20.830339][   T69]  ? netif_close_many_and_unlock (net/core/dev.c:12476)
[   20.830342][   T69]  ? trace_contention_end (./include/trace/events/lock.h:122 (discriminator 21))
[   20.830347][   T69]  unregister_netdevice_many_notify (net/core/dev.c:12545)
[   20.830351][   T69]  ? default_device_exit_batch (net/core/dev.c:13215)
[   20.830356][   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)
[   20.830359][   T69]  ? dev_ingress_queue_create (net/core/dev.c:12499)
[   20.830362][   T69]  ? rtnl_is_locked (net/core/rtnetlink.c:169)
[   20.830367][   T69]  ? unregister_netdevice_queue (net/core/dev.c:12442)
[   20.830370][   T69]  ? unregister_netdevice_many (net/core/dev.c:12441)
[   20.830373][   T69]  ? unregister_netdevice_many (net/core/dev.c:12441)
[   20.830379][   T69]  default_device_exit_batch (net/core/dev.c:13229)
[   20.830384][   T69]  ? unregister_netdev (net/core/dev.c:13204)
[   20.830390][   T69]  ops_undo_list (net/core/net_namespace.c:251)
[   20.830396][   T69]  ? rtnl_net_dumpid_one (net/core/net_namespace.c:223)
[   20.830399][   T69]  ? cleanup_net (./include/linux/list.h:191 net/core/net_namespace.c:693)
[   20.830406][   T69]  cleanup_net (net/core/net_namespace.c:698)
[   20.830410][   T69]  ? net_passive_dec (net/core/net_namespace.c:660)
[   20.830415][   T69]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   20.830423][   T69]  process_one_work (kernel/workqueue.c:3268)
[   20.830430][   T69]  ? pwq_dec_nr_in_flight (kernel/workqueue.c:3165)
[   20.830436][   T69]  ? assign_work (kernel/workqueue.c:1206)
[   20.830440][   T69]  worker_thread (kernel/workqueue.c:3340 kernel/workqueue.c:3427)
[   20.830446][   T69]  ? rescuer_thread (kernel/workqueue.c:3373)
[   20.830450][   T69]  kthread (kernel/kthread.c:463)
[   20.830455][   T69]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   20.830457][   T69]  ? ret_from_fork (arch/x86/kernel/process.c:157)
[   20.830464][   T69]  ? __lock_release (kernel/locking/lockdep.c:5536)
[   20.830469][   T69]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   20.830472][   T69]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   20.830476][   T69]  ret_from_fork (arch/x86/kernel/process.c:164)
[   20.830478][   T69]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   20.830481][   T69]  ret_from_fork_asm (arch/x86/entry/entry_64.S:255)
| [   20.840103][   T69] #PF: error_code(0x0002) - not-present page
| [   20.840300][   T69] PGD 0 P4D 0
| [   20.840426][   T69] Oops: Oops: 0002 [#1] SMP KASAN
| [   20.840962][   T69] Tainted: [B]=BAD_PAGE
[   20.841087][   T69] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   20.841291][   T69] Workqueue: netns cleanup_net
[   20.841467][   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)
[   20.841677][   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
[   20.842273][   T69] RSP: 0000:ffffc900004a7680 EFLAGS: 00010046
[   20.842483][   T69] RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffffa1e49b8a
[   20.842826][   T69] RDX: fffffbfff4d6cacd RSI: 0000000000000008 RDI: ffffffffa6b65660
[   20.843067][   T69] RBP: ffffc900004a76e8 R08: 0000000000000001 R09: fffffbfff4d6cacc
[   20.843305][   T69] R10: ffffffffa6b65667 R11: ffffc900004a7140 R12: 0000000000000000
[   20.843546][   T69] R13: 0000000000000282 R14: ffff88800b5fc000 R15: dffffc0000000000
[   20.843794][   T69] FS:  0000000000000000(0000) GS:ffff8880c6607000(0000) knlGS:0000000000000000
[   20.844085][   T69] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   20.844293][   T69] CR2: 0000000000000000 CR3: 000000003e549005 CR4: 0000000000772ef0
[   20.844537][   T69] PKRU: 55555554
[   20.844659][   T69] Call Trace:
[   20.844883][   T69]  <TASK>
[   20.844969][   T69]  __cancel_work (kernel/workqueue.c:2161 kernel/workqueue.c:4364)
[   20.845133][   T69]  ? enable_delayed_work (kernel/workqueue.c:4359)
[   20.845297][   T69]  ? queue_delayed_work_on (kernel/workqueue.c:2565 (discriminator 1))
[   20.845463][   T69]  __cancel_work_sync (kernel/workqueue.c:4383)
[   20.845621][   T69]  __dev_close_many (net/core/dev.c:1879 (discriminator 2) net/core/dev.c:1932 (discriminator 2))
[   20.845784][   T69]  ? netdev_notify_peers (net/core/dev.c:1891)
[   20.845949][   T69]  ? netif_close_many (net/core/dev.c:1959)
[   20.846109][   T69]  netif_close_many (net/core/dev.c:1959)
[   20.846365][   T69]  ? __mutex_handoff (kernel/locking/mutex.c:88)
[   20.846527][   T69]  ? __dev_close_many (net/core/dev.c:1949)
[   20.846689][   T69]  ? netif_close_many_and_unlock (net/core/dev.c:12476)
[   20.846989][   T69]  ? trace_contention_end (./include/trace/events/lock.h:122 (discriminator 21))
[   20.847151][   T69]  unregister_netdevice_many_notify (net/core/dev.c:12545)
[   20.847348][   T69]  ? default_device_exit_batch (net/core/dev.c:13215)
[   20.847601][   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)
[   20.847862][   T69]  ? dev_ingress_queue_create (net/core/dev.c:12499)
[   20.848022][   T69]  ? rtnl_is_locked (net/core/rtnetlink.c:169)
[   20.848184][   T69]  ? unregister_netdevice_queue (net/core/dev.c:12442)
[   20.848380][   T69]  ? unregister_netdevice_many (net/core/dev.c:12441)
[   20.848536][   T69]  ? unregister_netdevice_many (net/core/dev.c:12441)
[   20.848790][   T69]  default_device_exit_batch (net/core/dev.c:13229)
[   20.848955][   T69]  ? unregister_netdev (net/core/dev.c:13204)
[   20.849117][   T69]  ops_undo_list (net/core/net_namespace.c:251)
[   20.849278][   T69]  ? rtnl_net_dumpid_one (net/core/net_namespace.c:223)
[   20.849439][   T69]  ? cleanup_net (./include/linux/list.h:191 net/core/net_namespace.c:693)
[   20.849694][   T69]  cleanup_net (net/core/net_namespace.c:698)
[   20.849859][   T69]  ? net_passive_dec (net/core/net_namespace.c:660)
[   20.850017][   T69]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   20.850179][   T69]  process_one_work (kernel/workqueue.c:3268)
[   20.850339][   T69]  ? pwq_dec_nr_in_flight (kernel/workqueue.c:3165)
[   20.850503][   T69]  ? assign_work (kernel/workqueue.c:1206)
[   20.850664][   T69]  worker_thread (kernel/workqueue.c:3340 kernel/workqueue.c:3427)
[   20.850828][   T69]  ? rescuer_thread (kernel/workqueue.c:3373)
[   20.850993][   T69]  kthread (kernel/kthread.c:463)
[   20.851116][   T69]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   20.851273][   T69]  ? ret_from_fork (arch/x86/kernel/process.c:157)
[   20.851434][   T69]  ? __lock_release (kernel/locking/lockdep.c:5536)
[   20.851593][   T69]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   20.851757][   T69]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   20.851923][   T69]  ret_from_fork (arch/x86/kernel/process.c:164)
[   20.852083][   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