======================================
| xx__-> [   25.931461][  T243] ip (243) used greatest stack depth: 24392 bytes left
| [   27.997681][  T271] 8021q: 802.1Q VLAN Support v1.8
| [   28.627792][  T208] BUG: spinlock bad magic on CPU#2, kworker/2:2/208
| [ 28.627979][ T208] lock: noop_qdisc+0x240/0x300, .magic: 00000000, .owner: kworker/2:2/208, .owner_cpu: 2 
[   28.628426][  T208] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014
[   28.628696][  T208] Workqueue: mld mld_ifc_work
[   28.628837][  T208] Call Trace:
[   28.628933][  T208]  <TASK>
[ 28.629003][ T208] dump_stack_lvl (lib/dump_stack.c:122) 
[ 28.629129][ T208] do_raw_spin_unlock (kernel/locking/spinlock_debug.c:100 kernel/locking/spinlock_debug.c:141) 
[ 28.629261][ T208] _raw_spin_unlock (./arch/x86/include/asm/preempt.h:94 ./include/linux/spinlock_api_smp.h:143 kernel/locking/spinlock.c:186) 
[ 28.629386][ T208] __dev_xmit_skb (./include/net/sch_generic.h:226 ./include/net/sch_generic.h:217 net/core/dev.c:3879) 
[ 28.629511][ T208] ? __pfx___dev_xmit_skb (net/core/dev.c:3784) 
[ 28.629635][ T208] ? lockdep_hardirqs_on_prepare (kernel/locking/lockdep.c:4291 kernel/locking/lockdep.c:4358) 
[ 28.629799][ T208] __dev_queue_xmit (net/core/dev.c:4389) 
[ 28.629924][ T208] ? find_held_lock (kernel/locking/lockdep.c:5249) 
[ 28.630050][ T208] ? __lock_release (kernel/locking/lockdep.c:5435) 
[ 28.630176][ T208] ? ip6_finish_output2 (./include/net/neighbour.h:542 net/ipv6/ip6_output.c:137) 
[ 28.630300][ T208] ? __pfx___lock_release (kernel/locking/lockdep.c:5411) 
[ 28.630424][ T208] ? __pfx___dev_queue_xmit (net/core/dev.c:4332) 
[ 28.630545][ T208] ? mark_lock (kernel/locking/lockdep.c:4655 (discriminator 3)) 
[ 28.630641][ T208] ? mark_lock (kernel/locking/lockdep.c:4655 (discriminator 3)) 
[ 28.630734][ T208] ? mark_held_locks (kernel/locking/lockdep.c:4273) 
[ 28.630861][ T208] ? eth_header (net/ethernet/eth.c:100) 
[ 28.630995][ T208] ? neigh_connected_output (./include/linux/netdevice.h:3159 net/core/neighbour.c:1589) 
[ 28.631142][ T208] ip6_finish_output2 (./include/net/neighbour.h:542 net/ipv6/ip6_output.c:137) 
[ 28.631265][ T208] ip6_finish_output (net/ipv6/ip6_output.c:211 net/ipv6/ip6_output.c:222) 
[ 28.631420][ T208] ip6_output (./include/linux/netfilter.h:303 net/ipv6/ip6_output.c:243) 
[ 28.631517][ T208] ? __pfx_ip6_output (net/ipv6/ip6_output.c:230) 
[ 28.631639][ T208] ? lock_acquire.part.0 (kernel/locking/lockdep.c:466 kernel/locking/lockdep.c:5761) 
[ 28.631781][ T208] ? find_held_lock (kernel/locking/lockdep.c:5249) 
[ 28.631904][ T208] ? __lock_release (kernel/locking/lockdep.c:5435) 
[ 28.632031][ T208] ? icmp6_dst_alloc (net/ipv6/route.c:3295) 
[ 28.632156][ T208] NF_HOOK.constprop.0 (./include/linux/rcupdate.h:326 ./include/linux/rcupdate.h:838 ./include/linux/netfilter.h:238 ./include/linux/netfilter.h:312) 
[ 28.632292][ T208] ? __pfx_NF_HOOK.constprop.0 (./include/linux/netfilter.h:308) 
[ 28.632419][ T208] ? __pfx_xfrm_lookup_with_ifid (net/xfrm/xfrm_policy.c:3140) 
[ 28.632576][ T208] ? lockdep_hardirqs_on_prepare (kernel/locking/lockdep.c:4299 kernel/locking/lockdep.c:4358) 
[ 28.632753][ T208] ? icmp6_dst_alloc (net/ipv6/route.c:3295) 
[ 28.632880][ T208] ? __local_bh_enable_ip (./arch/x86/include/asm/irqflags.h:42 ./arch/x86/include/asm/irqflags.h:97 kernel/softirq.c:387) 
[ 28.633018][ T208] mld_sendpack (net/ipv6/mcast.c:1822) 
[ 28.633142][ T208] ? __pfx_mld_sendpack (net/ipv6/mcast.c:1779) 
[ 28.633276][ T208] ? mld_send_cr (net/ipv6/mcast.c:2096 (discriminator 11)) 
[ 28.633398][ T208] mld_ifc_work (net/ipv6/mcast.c:2652) 
[ 28.633539][ T208] process_one_work (kernel/workqueue.c:3231) 
[ 28.633668][ T208] ? __pfx___lock_release (kernel/locking/lockdep.c:5411) 
[ 28.633793][ T208] ? __pfx_process_one_work (kernel/workqueue.c:3133) 
[ 28.633917][ T208] ? assign_work (kernel/workqueue.c:1202) 
[ 28.634038][ T208] worker_thread (kernel/workqueue.c:3306 kernel/workqueue.c:3390) 
[ 28.634186][ T208] ? lockdep_hardirqs_on_prepare (kernel/locking/lockdep.c:4299 kernel/locking/lockdep.c:4358) 
[ 28.634339][ T208] ? __pfx_worker_thread (kernel/workqueue.c:3339) 
[ 28.634475][ T208] ? __pfx_worker_thread (kernel/workqueue.c:3339) 
[ 28.634596][ T208] kthread (kernel/kthread.c:389) 
[ 28.634692][ T208] ? __pfx_kthread (kernel/kthread.c:342) 
[ 28.634827][ T208] ret_from_fork (arch/x86/kernel/process.c:147) 
[ 28.634949][ T208] ? __pfx_kthread (kernel/kthread.c:342) 


Finger prints:
do_raw_spin_unlock:_raw_spin_unlock:__dev_xmit_skb:__dev_queue_xmit:ip6_finish_output2