======================================
| [   21.488508][  T255] ==================================================================
| [   21.488875][  T255] 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)
| [   21.489194][  T255] Write of size 8 at addr 0000000000000000 by task busy_poll_test./255
| [   21.489502][  T255]
[   21.489613][  T255] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   21.489615][  T255] Call Trace:
[   21.489617][  T255]  <TASK>
[   21.489619][  T255]  dump_stack_lvl (lib/dump_stack.c:123)
[   21.489629][  T255]  ? try_to_grab_pending (./arch/x86/include/asm/bitops.h:136 ./include/asm-generic/bitops/instrumented-atomic.h:72 kernel/workqueue.c:2072)
[   21.489632][  T255]  kasan_report (mm/kasan/report.c:597)
[   21.489641][  T255]  ? try_to_grab_pending (./arch/x86/include/asm/bitops.h:136 ./include/asm-generic/bitops/instrumented-atomic.h:72 kernel/workqueue.c:2072)
[   21.489647][  T255]  kasan_check_range (mm/kasan/generic.c:194 mm/kasan/generic.c:200)
[   21.489651][  T255]  try_to_grab_pending (./arch/x86/include/asm/bitops.h:136 ./include/asm-generic/bitops/instrumented-atomic.h:72 kernel/workqueue.c:2072)
[   21.489654][  T255]  ? page_pool_release (net/core/page_pool.c:1196)
[   21.489662][  T255]  __cancel_work (kernel/workqueue.c:2161 kernel/workqueue.c:4364)
[   21.489665][  T255]  ? enable_delayed_work (kernel/workqueue.c:4359)
[   21.489669][  T255]  ? page_pool_release (net/core/page_pool.c:1196)
[   21.489672][  T255]  ? page_pool_destroy (net/core/page_pool.c:1296)
[   21.489678][  T255]  __cancel_work_sync (kernel/workqueue.c:4383)
[   21.489682][  T255]  __dev_close_many (net/core/dev.c:1879 (discriminator 2) net/core/dev.c:1932 (discriminator 2))
[   21.489689][  T255]  ? netdev_notify_peers (net/core/dev.c:1891)
[   21.489692][  T255]  ? __mutex_lock (./arch/x86/include/asm/preempt.h:104 kernel/locking/mutex.c:739 kernel/locking/mutex.c:760)
[   21.489702][  T255]  netif_close_many (net/core/dev.c:1959)
[   21.489705][  T255]  ? ww_mutex_lock (kernel/locking/mutex.c:759)
[   21.489709][  T255]  ? __dev_close_many (net/core/dev.c:1949)
[   21.489712][  T255]  ? validate_chain (kernel/locking/lockdep.c:3801 kernel/locking/lockdep.c:3821 kernel/locking/lockdep.c:3876)
[   21.489719][  T255]  ? find_held_lock (kernel/locking/lockdep.c:5350)
[   21.489731][  T255]  netif_close_many_and_unlock (net/core/dev.c:12476)
[   21.489736][  T255]  unregister_netdevice_many_notify (net/core/dev.c:12539)
[   21.489741][  T255]  ? __mutex_handoff (kernel/locking/mutex.c:88)
[   21.489745][  T255]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   21.489753][  T255]  ? dev_ingress_queue_create (net/core/dev.c:12499)
[   21.489757][  T255]  ? __mutex_lock (./arch/x86/include/asm/preempt.h:104 kernel/locking/mutex.c:739 kernel/locking/mutex.c:760)
[   21.489760][  T255]  ? __rtnl_unlock (net/core/rtnetlink.c:145 (discriminator 3))
[   21.489766][  T255]  ? nsim_destroy (drivers/net/netdevsim/netdev.c:1174) netdevsim
[   21.489781][  T255]  ? ww_mutex_lock (kernel/locking/mutex.c:759)
[   21.489786][  T255]  unregister_netdevice_queue (net/core/dev.c:12452)
[   21.489790][  T255]  ? unregister_netdevice_many (net/core/dev.c:12441)
[   21.489797][  T255] nsim_destroy (drivers/net/netdevsim/netdev.c:1179 (discriminator 2)) netdevsim
[   21.489815][  T255] __nsim_dev_port_del (drivers/net/netdevsim/dev.c:443 drivers/net/netdevsim/dev.c:1528) netdevsim
[   21.489831][  T255] nsim_dev_reload_destroy (drivers/net/netdevsim/dev.c:1537 drivers/net/netdevsim/dev.c:1762) netdevsim
[   21.489843][  T255] nsim_drv_remove (drivers/net/netdevsim/dev.c:1779) netdevsim
[   21.489855][  T255]  device_release_driver_internal (drivers/base/dd.c:1276 drivers/base/dd.c:1297)
[   21.489862][  T255]  ? klist_put (lib/klist.c:220)
[   21.489867][  T255]  bus_remove_device (./include/linux/kobject.h:193 drivers/base/base.h:73 drivers/base/bus.c:586)
[   21.489872][  T255]  device_del (drivers/base/core.c:3879)
[   21.489876][  T255]  ? __device_link_del (drivers/base/core.c:3833)
[   21.489881][  T255]  device_unregister (drivers/base/core.c:3796 drivers/base/core.c:3920)
[   21.489884][  T255] del_device_store (drivers/net/netdevsim/bus.c:248) netdevsim
[   21.489897][  T255]  ? nsim_bus_dev_numvfs_show (drivers/net/netdevsim/bus.c:215) netdevsim
[   21.489906][  T255]  ? sysfs_file_kobj (./include/linux/rcupdate.h:341 ./include/linux/rcupdate.h:897 ./include/linux/rcupdate.h:1195 fs/sysfs/file.c:24)
[   21.489912][  T255]  ? sysfs_file_kobj (fs/sysfs/file.c:26)
[   21.489916][  T255]  ? sysfs_file_ops (fs/sysfs/file.c:135)
[   21.489918][  T255]  kernfs_fop_write_iter (fs/kernfs/file.c:88 fs/kernfs/file.c:356)
[   21.489922][  T255]  vfs_write (fs/read_write.c:594 fs/read_write.c:686)
[   21.489928][  T255]  ? kernel_write (fs/read_write.c:667)
[   21.489933][  T255]  ? __lock_acquire (kernel/locking/lockdep.c:5237)
[   21.489940][  T255]  ksys_write (fs/read_write.c:738)
[   21.489943][  T255]  ? __ia32_sys_read (fs/read_write.c:728)
[   21.489949][  T255]  do_syscall_64 (arch/x86/entry/syscall_64.c:63 arch/x86/entry/syscall_64.c:94)
[   21.489955][  T255]  entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)
[   21.489959][  T255] RIP: 0033:0x7f7aa2322257
[   21.489963][  T255] Code: 0f 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b7 0f 1f 00 f3 0f 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 51 c3 48 83 ec 28 48 89 54 24 18 48 89 74 24
All code
========
   0:	0f 00                	(bad)
   2:	f7 d8                	neg    %eax
   4:	64 89 02             	mov    %eax,%fs:(%rdx)
   7:	48 c7 c0 ff ff ff ff 	mov    $0xffffffffffffffff,%rax
   e:	eb b7                	jmp    0xffffffffffffffc7
  10:	0f 1f 00             	nopl   (%rax)
  13:	f3 0f 1e fa          	endbr64
  17:	64 8b 04 25 18 00 00 	mov    %fs:0x18,%eax
  1e:	00 
  1f:	85 c0                	test   %eax,%eax
  21:	75 10                	jne    0x33
  23:	b8 01 00 00 00       	mov    $0x1,%eax
  28:	0f 05                	syscall
  2a:*	48 3d 00 f0 ff ff    	cmp    $0xfffffffffffff000,%rax		<-- trapping instruction
  30:	77 51                	ja     0x83
  32:	c3                   	ret
  33:	48 83 ec 28          	sub    $0x28,%rsp
  37:	48 89 54 24 18       	mov    %rdx,0x18(%rsp)
  3c:	48                   	rex.W
  3d:	89                   	.byte 0x89
  3e:	74 24                	je     0x64

Code starting with the faulting instruction
===========================================
   0:	48 3d 00 f0 ff ff    	cmp    $0xfffffffffffff000,%rax
   6:	77 51                	ja     0x59
   8:	c3                   	ret
   9:	48 83 ec 28          	sub    $0x28,%rsp
   d:	48 89 54 24 18       	mov    %rdx,0x18(%rsp)
  12:	48                   	rex.W
  13:	89                   	.byte 0x89
  14:	74 24                	je     0x3a
[   21.489965][  T255] RSP: 002b:00007ffcf9003138 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
[   21.489969][  T255] RAX: ffffffffffffffda RBX: 00007f7aa241e780 RCX: 00007f7aa2322257
[   21.489971][  T255] RDX: 0000000000000004 RSI: 000055e1c8982bf0 RDI: 0000000000000001
[   21.489973][  T255] RBP: 0000000000000004 R08: 0000000000000000 R09: 00007f7aa23d4d20
[   21.489974][  T255] R10: 00007f7aa23d4c20 R11: 0000000000000246 R12: 0000000000000004
[   21.489976][  T255] R13: 000055e1c8982bf0 R14: 0000000000000004 R15: 00007f7aa24199c0
| [   21.505906][  T255] #PF: error_code(0x0002) - not-present page
| [   21.506144][  T255] PGD 0 P4D 0
| [   21.506297][  T255] Oops: Oops: 0002 [#1] SMP KASAN
| [   21.506959][  T255] Tainted: [B]=BAD_PAGE
[   21.507108][  T255] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   21.507351][  T255] 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)
[   21.507609][  T255] 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
[   21.508325][  T255] RSP: 0018:ffffc90000c17510 EFLAGS: 00010046
[   21.508572][  T255] RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff84649b8a
[   21.508884][  T255] RDX: fffffbfff126cacd RSI: 0000000000000008 RDI: ffffffff89365660
[   21.509199][  T255] RBP: ffffc90000c17578 R08: 0000000000000001 R09: fffffbfff126cacc
[   21.509494][  T255] R10: ffffffff89365667 R11: ffffc90000c17000 R12: 0000000000000000
[   21.509787][  T255] R13: 0000000000000282 R14: ffff888005a82000 R15: dffffc0000000000
[   21.510101][  T255] FS:  00007f7aa2222000(0000) GS:ffff8880e3d87000(0000) knlGS:0000000000000000
[   21.510465][  T255] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   21.510708][  T255] CR2: 0000000000000000 CR3: 000000000a95b005 CR4: 0000000000772ef0
[   21.511018][  T255] PKRU: 55555554
[   21.511165][  T255] Call Trace:
[   21.511311][  T255]  <TASK>
[   21.511409][  T255]  ? page_pool_release (net/core/page_pool.c:1196)
[   21.511613][  T255]  __cancel_work (kernel/workqueue.c:2161 kernel/workqueue.c:4364)
[   21.511827][  T255]  ? enable_delayed_work (kernel/workqueue.c:4359)
[   21.512023][  T255]  ? page_pool_release (net/core/page_pool.c:1196)
[   21.512216][  T255]  ? page_pool_destroy (net/core/page_pool.c:1296)
[   21.512412][  T255]  __cancel_work_sync (kernel/workqueue.c:4383)
[   21.512607][  T255]  __dev_close_many (net/core/dev.c:1879 (discriminator 2) net/core/dev.c:1932 (discriminator 2))
[   21.512820][  T255]  ? netdev_notify_peers (net/core/dev.c:1891)
[   21.513021][  T255]  ? __mutex_lock (./arch/x86/include/asm/preempt.h:104 kernel/locking/mutex.c:739 kernel/locking/mutex.c:760)
[   21.513219][  T255]  netif_close_many (net/core/dev.c:1959)
[   21.513411][  T255]  ? ww_mutex_lock (kernel/locking/mutex.c:759)
[   21.513604][  T255]  ? __dev_close_many (net/core/dev.c:1949)
[   21.513806][  T255]  ? validate_chain (kernel/locking/lockdep.c:3801 kernel/locking/lockdep.c:3821 kernel/locking/lockdep.c:3876)
[   21.514008][  T255]  ? find_held_lock (kernel/locking/lockdep.c:5350)
[   21.514203][  T255]  netif_close_many_and_unlock (net/core/dev.c:12476)
[   21.514397][  T255]  unregister_netdevice_many_notify (net/core/dev.c:12539)
[   21.514644][  T255]  ? __mutex_handoff (kernel/locking/mutex.c:88)
[   21.514860][  T255]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   21.515056][  T255]  ? dev_ingress_queue_create (net/core/dev.c:12499)
[   21.515251][  T255]  ? __mutex_lock (./arch/x86/include/asm/preempt.h:104 kernel/locking/mutex.c:739 kernel/locking/mutex.c:760)
[   21.515443][  T255]  ? __rtnl_unlock (net/core/rtnetlink.c:145 (discriminator 3))
[   21.515641][  T255]  ? nsim_destroy (drivers/net/netdevsim/netdev.c:1174) netdevsim
[   21.515867][  T255]  ? ww_mutex_lock (kernel/locking/mutex.c:759)
[   21.516069][  T255]  unregister_netdevice_queue (net/core/dev.c:12452)
[   21.516263][  T255]  ? unregister_netdevice_many (net/core/dev.c:12441)
[   21.516467][  T255] nsim_destroy (drivers/net/netdevsim/netdev.c:1179 (discriminator 2)) netdevsim
[   21.516671][  T255] __nsim_dev_port_del (drivers/net/netdevsim/dev.c:443 drivers/net/netdevsim/dev.c:1528) netdevsim
[   21.516933][  T255] nsim_dev_reload_destroy (drivers/net/netdevsim/dev.c:1537 drivers/net/netdevsim/dev.c:1762) netdevsim
[   21.517183][  T255] nsim_drv_remove (drivers/net/netdevsim/dev.c:1779) netdevsim
[   21.517409][  T255]  device_release_driver_internal (drivers/base/dd.c:1276 drivers/base/dd.c:1297)
[   21.517657][  T255]  ? klist_put (lib/klist.c:220)
[   21.517822][  T255]  bus_remove_device (./include/linux/kobject.h:193 drivers/base/base.h:73 drivers/base/bus.c:586)
[   21.518050][  T255]  device_del (drivers/base/core.c:3879)
[   21.518198][  T255]  ? __device_link_del (drivers/base/core.c:3833)
[   21.518411][  T255]  device_unregister (drivers/base/core.c:3796 drivers/base/core.c:3920)
[   21.518605][  T255] del_device_store (drivers/net/netdevsim/bus.c:248) netdevsim
[   21.518907][  T255]  ? nsim_bus_dev_numvfs_show (drivers/net/netdevsim/bus.c:215) netdevsim
[   21.519161][  T255]  ? sysfs_file_kobj (./include/linux/rcupdate.h:341 ./include/linux/rcupdate.h:897 ./include/linux/rcupdate.h:1195 fs/sysfs/file.c:24)
[   21.519362][  T255]  ? sysfs_file_kobj (fs/sysfs/file.c:26)
[   21.519573][  T255]  ? sysfs_file_ops (fs/sysfs/file.c:135)
[   21.519773][  T255]  kernfs_fop_write_iter (fs/kernfs/file.c:88 fs/kernfs/file.c:356)
[   21.519967][  T255]  vfs_write (fs/read_write.c:594 fs/read_write.c:686)
[   21.520119][  T255]  ? kernel_write (fs/read_write.c:667)
[   21.520314][  T255]  ? __lock_acquire (kernel/locking/lockdep.c:5237)
[   21.520516][  T255]  ksys_write (fs/read_write.c:738)
[   21.520661][  T255]  ? __ia32_sys_read (fs/read_write.c:728)
[   21.520864][  T255]  do_syscall_64 (arch/x86/entry/syscall_64.c:63 arch/x86/entry/syscall_64.c:94)
[   21.521059][  T255]  entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)
[   21.521298][  T255] RIP: 0033:0x7f7aa2322257
[   21.521501][  T255] Code: 0f 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b7 0f 1f 00 f3 0f 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 51 c3 48 83 ec 28 48 89 54 24 18 48 89 74 24
All code
========
   0:	0f 00                	(bad)
   2:	f7 d8                	neg    %eax
   4:	64 89 02             	mov    %eax,%fs:(%rdx)
   7:	48 c7 c0 ff ff ff ff 	mov    $0xffffffffffffffff,%rax
   e:	eb b7                	jmp    0xffffffffffffffc7
  10:	0f 1f 00             	nopl   (%rax)
  13:	f3 0f 1e fa          	endbr64
  17:	64 8b 04 25 18 00 00 	mov    %fs:0x18,%eax
  1e:	00 
  1f:	85 c0                	test   %eax,%eax
  21:	75 10                	jne    0x33
  23:	b8 01 00 00 00       	mov    $0x1,%eax
  28:	0f 05                	syscall
  2a:*	48 3d 00 f0 ff ff    	cmp    $0xfffffffffffff000,%rax		<-- trapping instruction
  30:	77 51                	ja     0x83
  32:	c3                   	ret
  33:	48 83 ec 28          	sub    $0x28,%rsp
  37:	48 89 54 24 18       	mov    %rdx,0x18(%rsp)
  3c:	48                   	rex.W
  3d:	89                   	.byte 0x89
  3e:	74 24                	je     0x64

Code starting with the faulting instruction
===========================================
   0:	48 3d 00 f0 ff ff    	cmp    $0xfffffffffffff000,%rax
   6:	77 51                	ja     0x59
   8:	c3                   	ret
   9:	48 83 ec 28          	sub    $0x28,%rsp
   d:	48 89 54 24 18       	mov    %rdx,0x18(%rsp)
  12:	48                   	rex.W
  13:	89                   	.byte 0x89
  14:	74 24                	je     0x3a
[   21.522195][  T255] RSP: 002b:00007ffcf9003138 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
[   21.522488][  T255] RAX: ffffffffffffffda RBX: 00007f7aa241e780 RCX: 00007f7aa2322257
[   21.522784][  T255] RDX: 0000000000000004 RSI: 000055e1c8982bf0 RDI: 0000000000000001
[   21.523074][  T255] RBP: 0000000000000004 R08: 0000000000000000 R09: 00007f7aa23d4d20
[   21.523370][  T255] R10: 00007f7aa23d4c20 R11: 0000000000000246 R12: 0000000000000004


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