======================================
| [ 1942.409733][   T69] ==================================================================
| [ 1942.410056][   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)
| [ 1942.410359][   T69] Write of size 8 at addr 0000000000000000 by task kworker/u16:1/69
| [ 1942.410606][   T69]
[ 1942.410710][   T69] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[ 1942.410715][   T69] Workqueue: netns cleanup_net
[ 1942.410742][   T69] Call Trace:
[ 1942.410746][   T69]  <TASK>
[ 1942.410749][   T69]  dump_stack_lvl (lib/dump_stack.c:123)
[ 1942.410762][   T69]  ? try_to_grab_pending (./arch/x86/include/asm/bitops.h:136 ./include/asm-generic/bitops/instrumented-atomic.h:72 kernel/workqueue.c:2072)
[ 1942.410765][   T69]  kasan_report (mm/kasan/report.c:597)
[ 1942.410777][   T69]  ? try_to_grab_pending (./arch/x86/include/asm/bitops.h:136 ./include/asm-generic/bitops/instrumented-atomic.h:72 kernel/workqueue.c:2072)
[ 1942.410782][   T69]  kasan_check_range (mm/kasan/generic.c:194 mm/kasan/generic.c:200)
[ 1942.410786][   T69]  try_to_grab_pending (./arch/x86/include/asm/bitops.h:136 ./include/asm-generic/bitops/instrumented-atomic.h:72 kernel/workqueue.c:2072)
[ 1942.410791][   T69]  __cancel_work (kernel/workqueue.c:2161 kernel/workqueue.c:4364)
[ 1942.410794][   T69]  ? enable_delayed_work (kernel/workqueue.c:4359)
[ 1942.410799][   T69]  ? queue_delayed_work_on (kernel/workqueue.c:2565 (discriminator 1))
[ 1942.410804][   T69]  __cancel_work_sync (kernel/workqueue.c:4383)
[ 1942.410808][   T69]  __dev_close_many (net/core/dev.c:1879 (discriminator 2) net/core/dev.c:1932 (discriminator 2))
[ 1942.410815][   T69]  ? netdev_notify_peers (net/core/dev.c:1891)
[ 1942.410818][   T69]  ? netif_close_many (net/core/dev.c:1959)
[ 1942.410823][   T69]  netif_close_many (net/core/dev.c:1959)
[ 1942.410826][   T69]  ? __mutex_handoff (kernel/locking/mutex.c:88)
[ 1942.410836][   T69]  ? __dev_close_many (net/core/dev.c:1949)
[ 1942.410839][   T69]  ? netif_close_many_and_unlock (net/core/dev.c:12476)
[ 1942.410842][   T69]  ? trace_contention_end (./include/trace/events/lock.h:122 (discriminator 21))
[ 1942.410846][   T69]  unregister_netdevice_many_notify (net/core/dev.c:12545)
[ 1942.410851][   T69]  ? default_device_exit_batch (net/core/dev.c:13215)
[ 1942.410855][   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)
[ 1942.410859][   T69]  ? dev_ingress_queue_create (net/core/dev.c:12499)
[ 1942.410862][   T69]  ? rtnl_is_locked (net/core/rtnetlink.c:169)
[ 1942.410867][   T69]  ? unregister_netdevice_queue (net/core/dev.c:12442)
[ 1942.410870][   T69]  ? unregister_netdevice_many (net/core/dev.c:12441)
[ 1942.410873][   T69]  ? unregister_netdevice_many (net/core/dev.c:12441)
[ 1942.410879][   T69]  default_device_exit_batch (net/core/dev.c:13229)
[ 1942.410883][   T69]  ? unregister_netdev (net/core/dev.c:13204)
[ 1942.410889][   T69]  ops_undo_list (net/core/net_namespace.c:251)
[ 1942.410894][   T69]  ? rtnl_net_dumpid_one (net/core/net_namespace.c:223)
[ 1942.410898][   T69]  ? cleanup_net (./include/linux/list.h:191 net/core/net_namespace.c:693)
[ 1942.410904][   T69]  cleanup_net (net/core/net_namespace.c:698)
[ 1942.410908][   T69]  ? net_passive_dec (net/core/net_namespace.c:660)
[ 1942.410913][   T69]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[ 1942.410920][   T69]  process_one_work (kernel/workqueue.c:3268)
[ 1942.410930][   T69]  ? pwq_dec_nr_in_flight (kernel/workqueue.c:3165)
[ 1942.410938][   T69]  ? assign_work (kernel/workqueue.c:1206)
[ 1942.410945][   T69]  worker_thread (kernel/workqueue.c:3340 kernel/workqueue.c:3427)
[ 1942.410951][   T69]  ? rescuer_thread (kernel/workqueue.c:3373)
[ 1942.410955][   T69]  kthread (kernel/kthread.c:463)
[ 1942.410962][   T69]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[ 1942.410964][   T69]  ? ret_from_fork (arch/x86/kernel/process.c:157)
[ 1942.410973][   T69]  ? __lock_release (kernel/locking/lockdep.c:5536)
[ 1942.410977][   T69]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[ 1942.410980][   T69]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[ 1942.410984][   T69]  ret_from_fork (arch/x86/kernel/process.c:164)
[ 1942.410986][   T69]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[ 1942.410989][   T69]  ret_from_fork_asm (arch/x86/entry/entry_64.S:255)
| [ 1942.421140][   T69] #PF: error_code(0x0002) - not-present page
| [ 1942.421388][   T69] PGD 0 P4D 0
| [ 1942.421521][   T69] Oops: Oops: 0002 [#1] SMP KASAN
| [ 1942.422082][   T69] Tainted: [B]=BAD_PAGE
[ 1942.422212][   T69] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[ 1942.422439][   T69] Workqueue: netns cleanup_net
[ 1942.422612][   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)
[ 1942.422840][   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
[ 1942.423443][   T69] RSP: 0018:ffffc900004a7680 EFLAGS: 00010046
[ 1942.423652][   T69] RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff86449b8a
[ 1942.423918][   T69] RDX: fffffbfff162cacd RSI: 0000000000000008 RDI: ffffffff8b165660
[ 1942.424169][   T69] RBP: ffffc900004a76e8 R08: 0000000000000001 R09: fffffbfff162cacc
[ 1942.424474][   T69] R10: ffffffff8b165667 R11: ffffc900004a7140 R12: 0000000000000000
[ 1942.424750][   T69] R13: 0000000000000282 R14: ffff888008ea4000 R15: dffffc0000000000
[ 1942.425001][   T69] FS:  0000000000000000(0000) GS:ffff8880e2087000(0000) knlGS:0000000000000000
[ 1942.425285][   T69] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 1942.425507][   T69] CR2: 0000000000000000 CR3: 000000000af73003 CR4: 0000000000772ef0
[ 1942.425770][   T69] PKRU: 55555554
[ 1942.425898][   T69] Call Trace:
[ 1942.426027][   T69]  <TASK>
[ 1942.426117][   T69]  __cancel_work (kernel/workqueue.c:2161 kernel/workqueue.c:4364)
[ 1942.426284][   T69]  ? enable_delayed_work (kernel/workqueue.c:4359)
[ 1942.426471][   T69]  ? queue_delayed_work_on (kernel/workqueue.c:2565 (discriminator 1))
[ 1942.426635][   T69]  __cancel_work_sync (kernel/workqueue.c:4383)
[ 1942.426812][   T69]  __dev_close_many (net/core/dev.c:1879 (discriminator 2) net/core/dev.c:1932 (discriminator 2))
[ 1942.426982][   T69]  ? netdev_notify_peers (net/core/dev.c:1891)
[ 1942.427145][   T69]  ? netif_close_many (net/core/dev.c:1959)
[ 1942.427322][   T69]  netif_close_many (net/core/dev.c:1959)
[ 1942.427492][   T69]  ? __mutex_handoff (kernel/locking/mutex.c:88)
[ 1942.427654][   T69]  ? __dev_close_many (net/core/dev.c:1949)
[ 1942.427831][   T69]  ? netif_close_many_and_unlock (net/core/dev.c:12476)
[ 1942.428036][   T69]  ? trace_contention_end (./include/trace/events/lock.h:122 (discriminator 21))
[ 1942.428206][   T69]  unregister_netdevice_many_notify (net/core/dev.c:12545)
[ 1942.428423][   T69]  ? default_device_exit_batch (net/core/dev.c:13215)
[ 1942.428584][   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)
[ 1942.428761][   T69]  ? dev_ingress_queue_create (net/core/dev.c:12499)
[ 1942.428923][   T69]  ? rtnl_is_locked (net/core/rtnetlink.c:169)
[ 1942.429089][   T69]  ? unregister_netdevice_queue (net/core/dev.c:12442)
[ 1942.429305][   T69]  ? unregister_netdevice_many (net/core/dev.c:12441)
[ 1942.429475][   T69]  ? unregister_netdevice_many (net/core/dev.c:12441)
[ 1942.429640][   T69]  default_device_exit_batch (net/core/dev.c:13229)
[ 1942.429818][   T69]  ? unregister_netdev (net/core/dev.c:13204)
[ 1942.429992][   T69]  ops_undo_list (net/core/net_namespace.c:251)
[ 1942.430157][   T69]  ? rtnl_net_dumpid_one (net/core/net_namespace.c:223)
[ 1942.430334][   T69]  ? cleanup_net (./include/linux/list.h:191 net/core/net_namespace.c:693)
[ 1942.430504][   T69]  cleanup_net (net/core/net_namespace.c:698)
[ 1942.430663][   T69]  ? net_passive_dec (net/core/net_namespace.c:660)
[ 1942.430842][   T69]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[ 1942.431014][   T69]  process_one_work (kernel/workqueue.c:3268)
[ 1942.431177][   T69]  ? pwq_dec_nr_in_flight (kernel/workqueue.c:3165)
[ 1942.431361][   T69]  ? assign_work (kernel/workqueue.c:1206)
[ 1942.431524][   T69]  worker_thread (kernel/workqueue.c:3340 kernel/workqueue.c:3427)
[ 1942.431737][   T69]  ? rescuer_thread (kernel/workqueue.c:3373)
[ 1942.431919][   T69]  kthread (kernel/kthread.c:463)
[ 1942.432051][   T69]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[ 1942.432236][   T69]  ? ret_from_fork (arch/x86/kernel/process.c:157)
[ 1942.432414][   T69]  ? __lock_release (kernel/locking/lockdep.c:5536)
[ 1942.432574][   T69]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[ 1942.432752][   T69]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[ 1942.432913][   T69]  ret_from_fork (arch/x86/kernel/process.c:164)
[ 1942.433086][   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