======================================
| [ 356.075031][ T11] #3: ffffffff93bf1088 (rtnl_mutex){+.+.}-{4:4}, at: cleanup_net (net/core/net_namespace.c:639)
| [ 356.075346][ T11] #4: ffffffff93bdfc30 ((netdev_chain).rwsem){++++}-{4:4}, at: blocking_notifier_call_chain (kernel/notifier.c:380 kernel/notifier.c:368)
| [  356.075672][   T11]
| [  356.075672][   T11] stack backtrace:
[  356.076140][   T11] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[  356.076348][   T11] Workqueue: netns cleanup_net
[  356.076518][   T11] Call Trace:
[  356.076647][   T11]  <TASK>
[ 356.076732][ T11] dump_stack_lvl (lib/dump_stack.c:123)
[ 356.076895][ T11] print_deadlock_bug (kernel/locking/lockdep.c:3040)
[ 356.077055][ T11] validate_chain (kernel/locking/lockdep.c:3894)
[ 356.077213][ T11] ? process_one_work (kernel/workqueue.c:3229)
[ 356.077372][ T11] ? __pfx_validate_chain (kernel/locking/lockdep.c:3860)
[ 356.077527][ 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)
[ 356.077693][ T11] ? mark_lock (kernel/locking/lockdep.c:4727 (discriminator 3))
[ 356.077812][ T11] __lock_acquire (kernel/locking/lockdep.c:5226)
[ 356.077967][ T11] lock_acquire.part.0 (kernel/locking/lockdep.c:467 kernel/locking/lockdep.c:5851)
[ 356.078150][ T11] ? blocking_notifier_call_chain (kernel/notifier.c:380 kernel/notifier.c:368)
[ 356.078356][ T11] ? mark_lock (kernel/locking/lockdep.c:4727 (discriminator 3))
[ 356.078500][ T11] ? __pfx_lock_acquire.part.0 (kernel/locking/lockdep.c:5814)
[ 356.078681][ T11] ? trace_lock_acquire (./include/trace/events/lock.h:24 (discriminator 37))
[ 356.078878][ T11] ? lock_acquire (kernel/locking/lockdep.c:5822)
[ 356.079066][ T11] ? blocking_notifier_call_chain (kernel/notifier.c:380 kernel/notifier.c:368)
[ 356.079249][ 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)
[ 356.079358][ T11] ? blocking_notifier_call_chain (kernel/notifier.c:380 kernel/notifier.c:368)
[ 356.079532][ T11] ? __pfx_down_read (kernel/locking/rwsem.c:1522)
[ 356.079708][ T11] ? __pfx_netlink_broadcast_filtered (net/netlink/af_netlink.c:1505)
[ 356.079893][ T11] blocking_notifier_call_chain (kernel/notifier.c:380 kernel/notifier.c:368)
[ 356.080076][ 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))
[ 356.080291][ T11] ? __pfx___netdev_upper_dev_unlink (net/core/dev.c:8151)
[ 356.080541][ T11] ? unregister_netdevice_queue (net/core/dev.c:11497)
[ 356.080777][ T11] ? __pfx_unregister_netdevice_queue (net/core/dev.c:11496)
[ 356.080994][ T11] ? __pfx_br_vlan_bridge_event (net/bridge/br_vlan.c:1739) bridge
[ 356.081231][ T11] netdev_upper_dev_unlink (net/core/dev.c:8190)
[ 356.081398][ T11] ? __pfx_netdev_upper_dev_unlink (net/core/dev.c:8190)
[ 356.081635][ T11] macvlan_device_event (drivers/net/macvlan.c:1829 (discriminator 3)) macvlan
[ 356.081861][ T11] ? br_device_event (net/bridge/br.c:40) bridge
[ 356.082111][ T11] ? __pfx_macvlan_device_event (drivers/net/macvlan.c:1779) macvlan
[ 356.082352][ T11] ? nft_offload_netdev_event (net/netfilter/nf_tables_offload.c:677) nf_tables
[ 356.082587][ T11] notifier_call_chain (kernel/notifier.c:85 (discriminator 2))
[ 356.082751][ T11] blocking_notifier_call_chain (kernel/notifier.c:381 kernel/notifier.c:368)
[ 356.082916][ T11] unregister_netdevice_many_notify (net/core/dev.c:11571)
[ 356.083164][ T11] ? mark_held_locks (kernel/locking/lockdep.c:4321)
[ 356.083331][ T11] ? __pfx_unregister_netdevice_many_notify (net/core/dev.c:11512)
[ 356.083529][ 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)
[ 356.083685][ T11] ? rtnl_is_locked (net/core/rtnetlink.c:164)
[ 356.083849][ 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)
[ 356.084066][ 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)
[ 356.084273][ T11] cleanup_net (net/core/net_namespace.c:644)
[ 356.084435][ T11] ? __pfx_lock_acquire.part.0 (kernel/locking/lockdep.c:5814)
[ 356.084594][ T11] ? __pfx_cleanup_net (net/core/net_namespace.c:592)
[ 356.084772][ T11] ? trace_lock_acquire (./include/trace/events/lock.h:24 (discriminator 37))
[ 356.084960][ T11] ? lock_acquire (kernel/locking/lockdep.c:5822)
[ 356.085150][ T11] ? process_one_work (kernel/workqueue.c:3205)
[ 356.085331][ T11] process_one_work (kernel/workqueue.c:3229)
[ 356.085542][ T11] ? __pfx___lock_release (kernel/locking/lockdep.c:5501)
[ 356.085743][ T11] ? __pfx_process_one_work (kernel/workqueue.c:3131)
[ 356.085957][ T11] ? assign_work (kernel/workqueue.c:1200)
[ 356.086145][ T11] worker_thread (kernel/workqueue.c:3304 kernel/workqueue.c:3391)
[ 356.086327][ T11] ? __pfx_worker_thread (kernel/workqueue.c:3337)
[ 356.086485][ T11] kthread (kernel/kthread.c:389)
[ 356.086594][ T11] ? __pfx_kthread (kernel/kthread.c:342)
[ 356.086744][ T11] ret_from_fork (arch/x86/kernel/process.c:147)
[ 356.086913][ T11] ? __pfx_kthread (kernel/kthread.c:342)


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