======================================
| [ 68.244187][ T11] #3: ffffffff8f9f1088 (rtnl_mutex){+.+.}-{4:4}, at: cleanup_net (net/core/net_namespace.c:639)
| [ 68.244482][ T11] #4: ffffffff8f9dfc30 ((netdev_chain).rwsem){++++}-{4:4}, at: blocking_notifier_call_chain (kernel/notifier.c:380 kernel/notifier.c:368)
| [   68.244804][   T11]
| [   68.244804][   T11] stack backtrace:
[   68.245268][   T11] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   68.245463][   T11] Workqueue: netns cleanup_net
[   68.245625][   T11] Call Trace:
[   68.245754][   T11]  <TASK>
[ 68.245838][ T11] dump_stack_lvl (lib/dump_stack.c:123)
[ 68.246001][ T11] print_deadlock_bug (kernel/locking/lockdep.c:3040)
[ 68.246160][ T11] validate_chain (kernel/locking/lockdep.c:3894)
[ 68.246321][ T11] ? process_one_work (kernel/workqueue.c:3229)
[ 68.246484][ T11] ? __pfx_validate_chain (kernel/locking/lockdep.c:3860)
[ 68.246641][ T11] ? 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)
[ 68.246802][ T11] ? mark_lock (kernel/locking/lockdep.c:4727 (discriminator 3))
[ 68.246928][ T11] __lock_acquire (kernel/locking/lockdep.c:5226)
[ 68.247086][ T11] lock_acquire.part.0 (kernel/locking/lockdep.c:467 kernel/locking/lockdep.c:5851)
[ 68.247243][ T11] ? blocking_notifier_call_chain (kernel/notifier.c:380 kernel/notifier.c:368)
[ 68.247439][ T11] ? mark_lock (kernel/locking/lockdep.c:4727 (discriminator 3))
[ 68.247560][ T11] ? __pfx_lock_acquire.part.0 (kernel/locking/lockdep.c:5814)
[ 68.247718][ T11] ? trace_lock_acquire (./include/trace/events/lock.h:24 (discriminator 37))
[ 68.247878][ T11] ? lock_acquire (kernel/locking/lockdep.c:5822)
[ 68.248037][ T11] ? blocking_notifier_call_chain (kernel/notifier.c:380 kernel/notifier.c:368)
[ 68.248236][ T11] down_read (./arch/x86/include/asm/preempt.h:79 kernel/locking/rwsem.c:1246 kernel/locking/rwsem.c:1261 kernel/locking/rwsem.c:1526)
[ 68.248363][ T11] ? blocking_notifier_call_chain (kernel/notifier.c:380 kernel/notifier.c:368)
[ 68.248566][ T11] ? __pfx_down_read (kernel/locking/rwsem.c:1522)
[ 68.248726][ T11] ? __pfx_netlink_broadcast_filtered (net/netlink/af_netlink.c:1505)
[ 68.248925][ T11] blocking_notifier_call_chain (kernel/notifier.c:380 kernel/notifier.c:368)
[ 68.249081][ T11] __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))
[ 68.249249][ T11] ? __pfx___netdev_upper_dev_unlink (net/core/dev.c:8151)
[ 68.249445][ T11] ? unregister_netdevice_queue (net/core/dev.c:11501)
[ 68.249638][ T11] ? __pfx_unregister_netdevice_queue (net/core/dev.c:11500)
[ 68.249837][ T11] ? __pfx_br_vlan_bridge_event (net/bridge/br_vlan.c:1739) bridge
[ 68.250082][ T11] netdev_upper_dev_unlink (net/core/dev.c:8190)
[ 68.250242][ T11] ? __pfx_netdev_upper_dev_unlink (net/core/dev.c:8190)
[ 68.250450][ T11] macvlan_device_event (drivers/net/macvlan.c:1829 (discriminator 3)) macvlan
[ 68.250648][ T11] ? br_device_event (net/bridge/br.c:40) bridge
[ 68.250840][ T11] ? __pfx_macvlan_device_event (drivers/net/macvlan.c:1779) macvlan
[ 68.251040][ T11] ? packet_notifier (net/packet/af_packet.c:4282)
[ 68.251200][ T11] notifier_call_chain (kernel/notifier.c:85 (discriminator 2))
[ 68.251364][ T11] blocking_notifier_call_chain (kernel/notifier.c:381 kernel/notifier.c:368)
[ 68.251529][ T11] unregister_netdevice_many_notify (net/core/dev.c:11575)
[ 68.251731][ T11] ? mark_held_locks (kernel/locking/lockdep.c:4321)
[ 68.251904][ T11] ? __pfx_unregister_netdevice_many_notify (net/core/dev.c:11516)
[ 68.252103][ T11] ? 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)
[ 68.252261][ T11] ? rtnl_is_locked (net/core/rtnetlink.c:163)
[ 68.252426][ T11] ? 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)
[ 68.252584][ T11] ? nexthop_net_exit_batch_rtnl (net/ipv4/nexthop.c:585 net/ipv4/nexthop.c:2158 net/ipv4/nexthop.c:2666 net/ipv4/nexthop.c:4010)
[ 68.252787][ T11] cleanup_net (net/core/net_namespace.c:644)
[ 68.252945][ T11] ? __pfx_lock_acquire.part.0 (kernel/locking/lockdep.c:5814)
[ 68.253105][ T11] ? __pfx_cleanup_net (net/core/net_namespace.c:592)
[ 68.253262][ T11] ? trace_lock_acquire (./include/trace/events/lock.h:24 (discriminator 37))
[ 68.253427][ T11] ? lock_acquire (kernel/locking/lockdep.c:5822)
[ 68.253584][ T11] ? process_one_work (kernel/workqueue.c:3205)
[ 68.253745][ T11] process_one_work (kernel/workqueue.c:3229)
[ 68.253906][ T11] ? __pfx___lock_release (kernel/locking/lockdep.c:5501)
[ 68.254068][ T11] ? __pfx_process_one_work (kernel/workqueue.c:3131)
[ 68.254228][ T11] ? assign_work (kernel/workqueue.c:1200)
[ 68.254393][ T11] worker_thread (kernel/workqueue.c:3304 kernel/workqueue.c:3391)
[ 68.254556][ T11] ? __pfx_worker_thread (kernel/workqueue.c:3337)
[ 68.254716][ T11] kthread (kernel/kthread.c:389)
[ 68.254837][ T11] ? __pfx_kthread (kernel/kthread.c:342)
[ 68.254995][ T11] ret_from_fork (arch/x86/kernel/process.c:147)
[ 68.255160][ T11] ? __pfx_kthread (kernel/kthread.c:342)


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