======================================
| 0
| xx__-> [   33.694996][  T293] ip (293) used greatest stack depth: 23136 bytes left
| [   77.257320][    C2] BUG: spinlock bad magic on CPU#2, kworker/u16:0/11
| [ 77.257535][ C2] lock: noop_qdisc+0x240/0x300, .magic: 00000000, .owner: kworker/u16:0/11, .owner_cpu: 2 
[   77.258010][    C2] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014
[   77.258303][    C2] Workqueue: netns cleanup_net
[   77.258440][    C2] Call Trace:
[   77.258543][    C2]  <IRQ>
[ 77.258613][ C2] dump_stack_lvl (lib/dump_stack.c:122) 
[ 77.258748][ C2] do_raw_spin_unlock (kernel/locking/spinlock_debug.c:100 kernel/locking/spinlock_debug.c:141) 
[ 77.258891][ C2] _raw_spin_unlock (./arch/x86/include/asm/preempt.h:94 ./include/linux/spinlock_api_smp.h:143 kernel/locking/spinlock.c:186) 
[ 77.259025][ C2] 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) 
[ 77.259159][ C2] handle_softirqs (kernel/softirq.c:554) 
[ 77.259296][ C2] ? 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) 
[ 77.259429][ C2] do_softirq (kernel/softirq.c:455 kernel/softirq.c:442) 
[   77.259526][    C2]  </IRQ>
[   77.259594][    C2]  <TASK>
[ 77.259658][ C2] __local_bh_enable_ip (kernel/softirq.c:382) 
[ 77.259785][ C2] dev_deactivate_many (net/sched/sch_generic.c:1356) 
[ 77.259914][ C2] __dev_close_many (net/core/dev.c:1547) 
[ 77.260043][ C2] ? __pfx___dev_close_many (net/core/dev.c:1522) 
[ 77.260170][ C2] ? mark_held_locks (kernel/locking/lockdep.c:4273) 
[ 77.260303][ C2] ? lockdep_hardirqs_on_prepare (kernel/locking/lockdep.c:4299 kernel/locking/lockdep.c:4358) 
[ 77.260464][ C2] __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) 
[ 77.260591][ C2] ? __pfx___dev_change_flags (net/core/dev.c:8802) 
[ 77.260718][ C2] ? trace_contention_end (./include/trace/events/lock.h:122 (discriminator 52)) 
[ 77.260847][ C2] dev_change_flags (net/core/dev.c:8910) 
[ 77.260976][ C2] cycle_netdev (drivers/net/vrf.c:1071) 
[ 77.261075][ C2] vrf_dellink (drivers/net/vrf.c:1690) 
[ 77.261171][ C2] ? __pfx_vrf_dellink (drivers/net/vrf.c:1686) 
[ 77.261303][ C2] default_device_exit_batch (net/core/dev.c:11884) 
[ 77.261431][ C2] ? __pfx_default_device_exit_batch (net/core/dev.c:11865) 
[ 77.261589][ C2] ? ops_exit_list (net/core/net_namespace.c:172 (discriminator 3)) 
[ 77.261719][ C2] cleanup_net (net/core/net_namespace.c:625 (discriminator 3)) 
[ 77.261847][ C2] ? __pfx_lock_acquire.part.0 (kernel/locking/lockdep.c:5724) 
[ 77.261976][ C2] ? __pfx_cleanup_net (net/core/net_namespace.c:570) 
[ 77.262101][ C2] ? trace_lock_acquire (./include/trace/events/lock.h:24 (discriminator 52)) 
[ 77.262229][ C2] ? process_one_work (kernel/workqueue.c:3207) 
[ 77.262360][ C2] ? lock_acquire (kernel/locking/lockdep.c:5732) 
[ 77.262486][ C2] ? process_one_work (kernel/workqueue.c:3207) 
[ 77.262613][ C2] process_one_work (kernel/workqueue.c:3231) 
[ 77.262741][ C2] ? __pfx___lock_release (kernel/locking/lockdep.c:5411) 
[ 77.262869][ C2] ? __pfx_process_one_work (kernel/workqueue.c:3133) 
[ 77.262998][ C2] ? assign_work (kernel/workqueue.c:1202) 
[ 77.263127][ C2] worker_thread (kernel/workqueue.c:3306 kernel/workqueue.c:3390) 
[ 77.263257][ C2] ? __pfx_worker_thread (kernel/workqueue.c:3339) 
[ 77.263386][ C2] kthread (kernel/kthread.c:389) 
[ 77.263484][ C2] ? __pfx_kthread (kernel/kthread.c:342) 
[ 77.263612][ C2] ret_from_fork (arch/x86/kernel/process.c:147) 
[ 77.263741][ C2] ? __pfx_kthread (kernel/kthread.c:342) 


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