======================================
| [ 579.889391][ T64] #3: ffffffff8f607e88 (rtnl_mutex){+.+.}-{4:4}, at: default_device_exit_batch (net/core/dev.c:12103)
| [ 579.889681][ T64] #4: ffffffff8f5f6a70 ((netdev_chain).rwsem){++++}-{4:4}, at: blocking_notifier_call_chain (kernel/notifier.c:380 kernel/notifier.c:368)
| [  579.889958][   T64]
| [  579.889958][   T64] stack backtrace:
[  579.890383][   T64] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[  579.890562][   T64] Workqueue: netns cleanup_net
[  579.890709][   T64] Call Trace:
[  579.890821][   T64]  <TASK>
[ 579.890898][ T64] dump_stack_lvl (lib/dump_stack.c:123)
[ 579.891044][ T64] print_deadlock_bug (kernel/locking/lockdep.c:3040)
[ 579.891182][ T64] validate_chain (kernel/locking/lockdep.c:3894)
[ 579.891326][ T64] ? __pfx_validate_chain (kernel/locking/lockdep.c:3860)
[ 579.891472][ T64] ? hlock_class (./arch/x86/include/asm/bitops.h:227 ./arch/x86/include/asm/bitops.h:239 ./include/asm-generic/bitops/instrumented-non-atomic.h:142 kernel/locking/lockdep.c:228)
[ 579.891611][ T64] ? mark_lock (kernel/locking/lockdep.c:4727 (discriminator 3))
[ 579.891717][ T64] __lock_acquire (kernel/locking/lockdep.c:5226)
[ 579.891863][ T64] lock_acquire.part.0 (kernel/locking/lockdep.c:467 kernel/locking/lockdep.c:5851)
[ 579.892003][ T64] ? blocking_notifier_call_chain (kernel/notifier.c:380 kernel/notifier.c:368)
[ 579.892175][ T64] ? __lock_acquire (kernel/locking/lockdep.c:5226)
[ 579.892313][ T64] ? __pfx_lock_acquire.part.0 (kernel/locking/lockdep.c:5814)
[ 579.892453][ T64] ? trace_lock_acquire (./include/trace/events/lock.h:24 (discriminator 37))
[ 579.892592][ T64] ? lock_acquire (kernel/locking/lockdep.c:5822)
[ 579.892727][ T64] ? blocking_notifier_call_chain (kernel/notifier.c:380 kernel/notifier.c:368)
[ 579.892900][ T64] down_read (./arch/x86/include/asm/preempt.h:79 kernel/locking/rwsem.c:1246 kernel/locking/rwsem.c:1261 kernel/locking/rwsem.c:1526)
[ 579.893011][ T64] ? blocking_notifier_call_chain (kernel/notifier.c:380 kernel/notifier.c:368)
[ 579.893180][ T64] ? __pfx_down_read (kernel/locking/rwsem.c:1522)
[ 579.893321][ T64] ? __lock_release (kernel/locking/lockdep.c:5525)
[ 579.893460][ T64] blocking_notifier_call_chain (kernel/notifier.c:380 kernel/notifier.c:368)
[ 579.893602][ T64] __netdev_upper_dev_unlink (net/core/dev.c:8000 (discriminator 11) net/core/dev.c:8017 (discriminator 11) net/core/dev.c:8167 (discriminator 11))
[ 579.893741][ T64] ? mark_held_locks (kernel/locking/lockdep.c:4321)
[ 579.893879][ T64] ? __pfx___netdev_upper_dev_unlink (net/core/dev.c:8151)
[ 579.894050][ T64] ? lockdep_hardirqs_on_prepare (kernel/locking/lockdep.c:4347 kernel/locking/lockdep.c:4406)
[ 579.894220][ T64] ? __try_to_del_timer_sync (kernel/time/timer.c:1498)
[ 579.894362][ T64] ? __pfx___try_to_del_timer_sync (kernel/time/timer.c:1498)
[ 579.894535][ T64] ? mark_held_locks (kernel/locking/lockdep.c:4321)
[ 579.894677][ T64] netdev_upper_dev_unlink (net/core/dev.c:8190)
[ 579.894816][ T64] ? __pfx_netdev_upper_dev_unlink (net/core/dev.c:8190)
[ 579.894986][ T64] ? 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:66)
[ 579.895126][ T64] ? rtnl_is_locked (net/core/rtnetlink.c:164)
[ 579.895271][ T64] ? netdev_master_upper_dev_get (net/core/dev.c:7230)
[ 579.895446][ T64] vrf_device_event (drivers/net/vrf.c:1110 drivers/net/vrf.c:1119 drivers/net/vrf.c:1804)
[ 579.895585][ T64] notifier_call_chain (kernel/notifier.c:85 (discriminator 2))
[ 579.895724][ T64] blocking_notifier_call_chain (kernel/notifier.c:381 kernel/notifier.c:368)
[ 579.895866][ T64] unregister_netdevice_many_notify (net/core/dev.c:11571)
[ 579.896040][ T64] ? __pfx_unregister_netdevice_many_notify (net/core/dev.c:11512)
[ 579.896213][ T64] ? default_device_exit_batch (net/core/dev.c:12103)
[ 579.896353][ T64] ? rtnl_is_locked (net/core/rtnetlink.c:164)
[ 579.896491][ T64] ? unregister_netdevice_queue (net/core/dev.c:11497)
[ 579.896661][ T64] ? __pfx_unregister_netdevice_queue (net/core/dev.c:11496)
[ 579.896832][ T64] ? __pfx_unregister_netdevice_queue (net/core/dev.c:11496)
[ 579.897004][ T64] default_device_exit_batch (net/core/dev.c:12117)
[ 579.897143][ T64] ? __pfx_default_device_exit_batch (net/core/dev.c:12092)
[ 579.897314][ T64] ? ops_exit_list (net/core/net_namespace.c:171 (discriminator 3))
[ 579.897455][ T64] cleanup_net (net/core/net_namespace.c:647 (discriminator 3))
[ 579.897593][ T64] ? __pfx_lock_acquire.part.0 (kernel/locking/lockdep.c:5814)
[ 579.897733][ T64] ? __pfx_cleanup_net (net/core/net_namespace.c:592)
[ 579.897870][ T64] ? trace_lock_acquire (./include/trace/events/lock.h:24 (discriminator 37))
[ 579.898010][ T64] ? lock_acquire (kernel/locking/lockdep.c:5822)
[ 579.898146][ T64] ? process_one_work (kernel/workqueue.c:3205)
[ 579.898291][ T64] process_one_work (kernel/workqueue.c:3229)
[ 579.898431][ T64] ? __pfx___lock_release (kernel/locking/lockdep.c:5501)
[ 579.898569][ T64] ? __pfx_process_one_work (kernel/workqueue.c:3131)
[ 579.898704][ T64] ? assign_work (kernel/workqueue.c:1200)
[ 579.898845][ T64] worker_thread (kernel/workqueue.c:3304 kernel/workqueue.c:3391)
[ 579.898984][ T64] ? lockdep_hardirqs_on_prepare (kernel/locking/lockdep.c:4347 kernel/locking/lockdep.c:4406)
[ 579.899155][ T64] ? __pfx_worker_thread (kernel/workqueue.c:3337)
[ 579.899298][ T64] ? __pfx_worker_thread (kernel/workqueue.c:3337)
[ 579.899439][ T64] kthread (kernel/kthread.c:389)
[ 579.899549][ T64] ? __pfx_kthread (kernel/kthread.c:342)
[ 579.899688][ T64] ret_from_fork (arch/x86/kernel/process.c:147)
[ 579.899828][ T64] ? __pfx_kthread (kernel/kthread.c:342)


Finger prints:
print_deadlock_bug:validate_chain:__lock_acquire:down_read:blocking_notifier_call_chain