======================================
| 0
| xx__-> [   37.353423][  T332] ip (332) used greatest stack depth: 24048 bytes left
| [   77.992270][    C0] BUG: spinlock bad magic on CPU#0, kworker/u16:1/74
| [ 77.992478][ C0] lock: noop_qdisc+0x240/0x300, .magic: 00000000, .owner: kworker/u16:1/74, .owner_cpu: 0 
[   77.993000][    C0] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014
[   77.993336][    C0] Workqueue: netns cleanup_net
[   77.993491][    C0] Call Trace:
[   77.993605][    C0]  <IRQ>
[ 77.993680][ C0] dump_stack_lvl (lib/dump_stack.c:122) 
[ 77.993833][ C0] do_raw_spin_unlock (kernel/locking/spinlock_debug.c:100 kernel/locking/spinlock_debug.c:141) 
[ 77.993980][ C0] _raw_spin_unlock (./arch/x86/include/asm/preempt.h:94 ./include/linux/spinlock_api_smp.h:143 kernel/locking/spinlock.c:186) 
[ 77.994125][ C0] net_tx_action (./include/net/sch_generic.h:226 ./include/net/sch_generic.h:217 ./include/net/pkt_sched.h:128 ./include/net/pkt_sched.h:124 net/core/dev.c:5323) 
[ 77.994278][ C0] handle_softirqs (kernel/softirq.c:554) 
[ 77.994424][ C0] ? dev_deactivate_many (./include/linux/bottom_half.h:33 ./include/linux/netdevice.h:4448 net/sched/sch_generic.c:571 net/sched/sch_generic.c:1363) 
[ 77.994575][ C0] do_softirq (kernel/softirq.c:455 kernel/softirq.c:442) 
[   77.994686][    C0]  </IRQ>
[   77.994759][    C0]  <TASK>
[ 77.994831][ C0] __local_bh_enable_ip (kernel/softirq.c:382) 
[ 77.994976][ C0] dev_deactivate_many (net/sched/sch_generic.c:1356) 
[ 77.995131][ C0] __dev_close_many (net/core/dev.c:1547) 
[ 77.995278][ C0] ? __pfx___dev_close_many (net/core/dev.c:1522) 
[ 77.995423][ C0] ? mark_held_locks (kernel/locking/lockdep.c:4273) 
[ 77.995557][ C0] ? lockdep_hardirqs_on_prepare (kernel/locking/lockdep.c:4299 kernel/locking/lockdep.c:4358) 
[ 77.995743][ C0] __dev_change_flags (./include/linux/list.h:111 ./include/linux/list.h:215 ./include/linux/list.h:229 net/core/dev.c:1571 net/core/dev.c:8836) 
[ 77.995880][ C0] ? __pfx___dev_change_flags (net/core/dev.c:8802) 
[ 77.996024][ C0] ? trace_contention_end (./include/trace/events/lock.h:122 (discriminator 52)) 
[ 77.996167][ C0] dev_change_flags (net/core/dev.c:8910) 
[ 77.996309][ C0] cycle_netdev (drivers/net/vrf.c:1071) 
[ 77.996420][ C0] vrf_dellink (drivers/net/vrf.c:1690) 
[ 77.996527][ C0] ? __pfx_vrf_dellink (drivers/net/vrf.c:1686) 
[ 77.996672][ C0] default_device_exit_batch (net/core/dev.c:11884) 
[ 77.996817][ C0] ? __pfx_default_device_exit_batch (net/core/dev.c:11865) 
[ 77.996994][ C0] ? ops_exit_list (net/core/net_namespace.c:172 (discriminator 3)) 
[ 77.997138][ C0] cleanup_net (net/core/net_namespace.c:625 (discriminator 3)) 
[ 77.997279][ C0] ? __pfx_lock_acquire.part.0 (kernel/locking/lockdep.c:5724) 
[ 77.997419][ C0] ? __pfx_cleanup_net (net/core/net_namespace.c:570) 
[ 77.997562][ C0] ? trace_lock_acquire (./include/trace/events/lock.h:24 (discriminator 52)) 
[ 77.997708][ C0] ? process_one_work (kernel/workqueue.c:3207) 
[ 77.997848][ C0] ? lock_acquire (kernel/locking/lockdep.c:5732) 
[ 77.997991][ C0] ? process_one_work (kernel/workqueue.c:3207) 
[ 77.998134][ C0] process_one_work (kernel/workqueue.c:3231) 
[ 77.998281][ C0] ? __pfx___lock_release (kernel/locking/lockdep.c:5411) 
[ 77.998425][ C0] ? __pfx_process_one_work (kernel/workqueue.c:3133) 
[ 77.998568][ C0] ? assign_work (kernel/workqueue.c:1202) 
[ 77.998719][ C0] worker_thread (kernel/workqueue.c:3306 kernel/workqueue.c:3390) 
[ 77.998863][ C0] ? lockdep_hardirqs_on_prepare (kernel/locking/lockdep.c:4299 kernel/locking/lockdep.c:4358) 
[ 77.999036][ C0] ? __pfx_worker_thread (kernel/workqueue.c:3339) 
[ 77.999187][ C0] ? __pfx_worker_thread (kernel/workqueue.c:3339) 
[ 77.999325][ C0] kthread (kernel/kthread.c:389) 
[ 77.999435][ C0] ? __pfx_kthread (kernel/kthread.c:342) 
[ 77.999646][ C0] ret_from_fork (arch/x86/kernel/process.c:147) 
[ 77.999790][ C0] ? __pfx_kthread (kernel/kthread.c:342) 


Finger prints:
do_raw_spin_unlock:_raw_spin_unlock:net_tx_action:handle_softirqs:do_softirq