======================================
| [ 44.941422][ T65] #3: ffffffff905e7a48 (rtnl_mutex){+.+.}-{4:4}, at: cleanup_net (net/core/net_namespace.c:639)
| [ 44.941673][ T65] #4: ffffffff905d6630 ((netdev_chain).rwsem){++++}-{4:4}, at: blocking_notifier_call_chain (kernel/notifier.c:380 kernel/notifier.c:368)
| [   44.941953][   T65]
| [   44.941953][   T65] stack backtrace:
[   44.942375][   T65] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   44.942555][   T65] Workqueue: netns cleanup_net
[   44.942700][   T65] Call Trace:
[   44.942821][   T65]  <TASK>
[ 44.942891][ T65] dump_stack_lvl (lib/dump_stack.c:123)
[ 44.943053][ T65] print_deadlock_bug (kernel/locking/lockdep.c:3040)
[ 44.943215][ T65] validate_chain (kernel/locking/lockdep.c:3894)
[ 44.943369][ T65] ? __pfx_validate_chain (kernel/locking/lockdep.c:3860)
[ 44.943522][ T65] ? 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)
[ 44.943673][ T65] ? mark_lock (kernel/locking/lockdep.c:4727 (discriminator 3))
[ 44.943781][ T65] __lock_acquire (kernel/locking/lockdep.c:5226)
[ 44.943935][ T65] ? spin_bug (kernel/locking/spinlock_debug.c:57 kernel/locking/spinlock_debug.c:78)
[ 44.944045][ T65] ? debug_object_assert_init (./include/linux/err.h:81 lib/debugobjects.c:1010)
[ 44.944196][ T65] lock_acquire.part.0 (kernel/locking/lockdep.c:467 kernel/locking/lockdep.c:5851)
[ 44.944344][ T65] ? blocking_notifier_call_chain (kernel/notifier.c:380 kernel/notifier.c:368)
[ 44.944521][ T65] ? __pfx_lock_acquire.part.0 (kernel/locking/lockdep.c:5814)
[ 44.944666][ T65] ? trace_lock_acquire (./include/trace/events/lock.h:24 (discriminator 37))
[ 44.944808][ T65] ? lock_acquire (kernel/locking/lockdep.c:5822)
[ 44.944950][ T65] ? blocking_notifier_call_chain (kernel/notifier.c:380 kernel/notifier.c:368)
[ 44.945130][ T65] down_read (./arch/x86/include/asm/preempt.h:79 kernel/locking/rwsem.c:1246 kernel/locking/rwsem.c:1261 kernel/locking/rwsem.c:1526)
[ 44.945241][ T65] ? blocking_notifier_call_chain (kernel/notifier.c:380 kernel/notifier.c:368)
[ 44.945421][ T65] ? __pfx_down_read (kernel/locking/rwsem.c:1522)
[ 44.945573][ T65] blocking_notifier_call_chain (kernel/notifier.c:380 kernel/notifier.c:368)
[ 44.945712][ T65] __dev_close_many (net/core/dev.c:1537 (discriminator 3))
[ 44.945853][ T65] ? __pfx___dev_close_many (net/core/dev.c:1525)
[ 44.945999][ T65] dev_close_many (net/core/dev.c:1588)
[ 44.946151][ T65] ? __lock_release (kernel/locking/lockdep.c:5525)
[ 44.946307][ T65] ? __pfx_dev_close_many (net/core/dev.c:1578)
[ 44.946472][ T65] ? __pfx___lock_release (kernel/locking/lockdep.c:5501)
[ 44.946612][ T65] ? __pfx_lock_acquire.part.0 (kernel/locking/lockdep.c:5814)
[ 44.946772][ T65] vlan_device_event (net/8021q/vlan.c:451) 8021q
[ 44.946954][ T65] ? net_generic (./include/net/netns/generic.h:51) vxlan
[ 44.947107][ T65] ? __pfx_vlan_device_event (net/8021q/vlan.c:362) 8021q
[ 44.947300][ T65] ? __pfx_vxlan_netdevice_event (drivers/net/vxlan/vxlan_core.c:4737) vxlan
[ 44.947487][ T65] ? packet_notifier (net/packet/af_packet.c:4282)
[ 44.947655][ T65] notifier_call_chain (kernel/notifier.c:85 (discriminator 2))
[ 44.947805][ T65] blocking_notifier_call_chain (kernel/notifier.c:381 kernel/notifier.c:368)
[ 44.947960][ T65] dev_close_many (net/core/dev.c:1591)
[ 44.948105][ T65] ? __lock_release (kernel/locking/lockdep.c:5525)
[ 44.948244][ T65] ? __virt_addr_valid (./include/linux/rcupdate.h:347 ./include/linux/rcupdate.h:962 ./include/linux/mmzone.h:2058 arch/x86/mm/physaddr.c:65)
[ 44.948393][ T65] ? __pfx_dev_close_many (net/core/dev.c:1578)
[ 44.948615][ T65] unregister_netdevice_many_notify (net/core/dev.c:11545)
[ 44.948870][ T65] ? mark_held_locks (kernel/locking/lockdep.c:4321)
[ 44.949014][ T65] ? __pfx_unregister_netdevice_many_notify (net/core/dev.c:11512)
[ 44.949193][ T65] ? 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)
[ 44.949336][ T65] ? rtnl_is_locked (net/core/rtnetlink.c:164)
[ 44.949485][ T65] ? __pfx_unregister_netdevice_queue (net/core/dev.c:11496)
[ 44.949664][ T65] ? 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)
[ 44.949814][ T65] ? 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)
[ 44.949987][ T65] cleanup_net (net/core/net_namespace.c:644)
[ 44.950207][ T65] ? __pfx_lock_acquire.part.0 (kernel/locking/lockdep.c:5814)
[ 44.950348][ T65] ? __pfx_cleanup_net (net/core/net_namespace.c:592)
[ 44.950490][ T65] ? trace_lock_acquire (./include/trace/events/lock.h:24 (discriminator 37))
[ 44.950630][ T65] ? lock_acquire (kernel/locking/lockdep.c:5822)
[ 44.950772][ T65] ? process_one_work (kernel/workqueue.c:3205)
[ 44.951002][ T65] process_one_work (kernel/workqueue.c:3229)
[ 44.951146][ T65] ? __pfx___lock_release (kernel/locking/lockdep.c:5501)
[ 44.951286][ T65] ? __pfx_process_one_work (kernel/workqueue.c:3131)
[ 44.951429][ T65] ? assign_work (kernel/workqueue.c:1200)
[ 44.951650][ T65] worker_thread (kernel/workqueue.c:3304 kernel/workqueue.c:3391)
[ 44.951787][ T65] ? lockdep_hardirqs_on_prepare (kernel/locking/lockdep.c:4347 kernel/locking/lockdep.c:4406)
[ 44.951978][ T65] ? __pfx_worker_thread (kernel/workqueue.c:3337)
[ 44.952115][ T65] ? __pfx_worker_thread (kernel/workqueue.c:3337)
[ 44.952337][ T65] kthread (kernel/kthread.c:389)
[ 44.952443][ T65] ? __pfx_kthread (kernel/kthread.c:342)
[ 44.952581][ T65] ret_from_fork (arch/x86/kernel/process.c:147)
[ 44.952720][ T65] ? __pfx_kthread (kernel/kthread.c:342)


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