======================================
| xx__-> [   25.769088][  T241] ip (241) used greatest stack depth: 23760 bytes left
| [   29.434689][  T284] 8021q: 802.1Q VLAN Support v1.8
| [   30.026980][    T9] BUG: spinlock bad magic on CPU#0, kworker/0:1/9
| [ 30.027184][ T9] lock: noop_qdisc+0x240/0x300, .magic: 00000000, .owner: kworker/0:1/9, .owner_cpu: 0 
[   30.027654][    T9] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014
[   30.027974][    T9] Workqueue: mld mld_ifc_work
[   30.028118][    T9] Call Trace:
[   30.028226][    T9]  <TASK>
[ 30.028300][ T9] dump_stack_lvl (lib/dump_stack.c:122) 
[ 30.028445][ T9] do_raw_spin_unlock (kernel/locking/spinlock_debug.c:100 kernel/locking/spinlock_debug.c:141) 
[ 30.028597][ T9] _raw_spin_unlock (./arch/x86/include/asm/preempt.h:94 ./include/linux/spinlock_api_smp.h:143 kernel/locking/spinlock.c:186) 
[ 30.028735][ T9] __dev_xmit_skb (./include/net/sch_generic.h:226 ./include/net/sch_generic.h:217 net/core/dev.c:3879) 
[ 30.028882][ T9] ? __pfx___dev_xmit_skb (net/core/dev.c:3784) 
[ 30.029029][ T9] ? lockdep_hardirqs_on_prepare (kernel/locking/lockdep.c:4291 kernel/locking/lockdep.c:4358) 
[ 30.029199][ T9] __dev_queue_xmit (net/core/dev.c:4389) 
[ 30.029337][ T9] ? find_held_lock (kernel/locking/lockdep.c:5249) 
[ 30.029480][ T9] ? __lock_release (kernel/locking/lockdep.c:5435) 
[ 30.029622][ T9] ? ip6_finish_output2 (./include/net/neighbour.h:542 net/ipv6/ip6_output.c:137) 
[ 30.029758][ T9] ? __pfx___lock_release (kernel/locking/lockdep.c:5411) 
[ 30.029897][ T9] ? __pfx___dev_queue_xmit (net/core/dev.c:4332) 
[ 30.030033][ T9] ? mark_lock (kernel/locking/lockdep.c:4655 (discriminator 3)) 
[ 30.030142][ T9] ? mark_lock (kernel/locking/lockdep.c:4655 (discriminator 3)) 
[ 30.030247][ T9] ? mark_held_locks (kernel/locking/lockdep.c:4273) 
[ 30.030387][ T9] ? eth_header (net/ethernet/eth.c:100) 
[ 30.030528][ T9] ? neigh_connected_output (./include/linux/netdevice.h:3159 net/core/neighbour.c:1589) 
[ 30.030667][ T9] ip6_finish_output2 (./include/net/neighbour.h:542 net/ipv6/ip6_output.c:137) 
[ 30.030805][ T9] ip6_finish_output (net/ipv6/ip6_output.c:211 net/ipv6/ip6_output.c:222) 
[ 30.030946][ T9] ip6_output (./include/linux/netfilter.h:303 net/ipv6/ip6_output.c:243) 
[ 30.031051][ T9] ? __pfx_ip6_output (net/ipv6/ip6_output.c:230) 
[ 30.031190][ T9] ? lock_acquire.part.0 (kernel/locking/lockdep.c:466 kernel/locking/lockdep.c:5761) 
[ 30.031331][ T9] ? find_held_lock (kernel/locking/lockdep.c:5249) 
[ 30.031484][ T9] ? __lock_release (kernel/locking/lockdep.c:5435) 
[ 30.031623][ T9] ? icmp6_dst_alloc (net/ipv6/route.c:3295) 
[ 30.031766][ T9] NF_HOOK.constprop.0 (./include/linux/rcupdate.h:326 ./include/linux/rcupdate.h:838 ./include/linux/netfilter.h:238 ./include/linux/netfilter.h:312) 
[ 30.031910][ T9] ? __pfx_NF_HOOK.constprop.0 (./include/linux/netfilter.h:308) 
[ 30.032043][ T9] ? __pfx_xfrm_lookup_with_ifid (net/xfrm/xfrm_policy.c:3140) 
[ 30.032215][ T9] ? lockdep_hardirqs_on_prepare (kernel/locking/lockdep.c:4299 kernel/locking/lockdep.c:4358) 
[ 30.032382][ T9] ? icmp6_dst_alloc (net/ipv6/route.c:3295) 
[ 30.032546][ T9] ? __local_bh_enable_ip (./arch/x86/include/asm/irqflags.h:42 ./arch/x86/include/asm/irqflags.h:97 kernel/softirq.c:387) 
[ 30.032687][ T9] mld_sendpack (net/ipv6/mcast.c:1822) 
[ 30.032825][ T9] ? __pfx_mld_sendpack (net/ipv6/mcast.c:1779) 
[ 30.032965][ T9] ? mld_send_cr (net/ipv6/mcast.c:2096 (discriminator 11)) 
[ 30.033098][ T9] mld_ifc_work (net/ipv6/mcast.c:2652) 
[ 30.033238][ T9] process_one_work (kernel/workqueue.c:3231) 
[ 30.033381][ T9] ? __pfx___lock_release (kernel/locking/lockdep.c:5411) 
[ 30.033526][ T9] ? __pfx_process_one_work (kernel/workqueue.c:3133) 
[ 30.033674][ T9] ? assign_work (kernel/workqueue.c:1202) 
[ 30.033828][ T9] worker_thread (kernel/workqueue.c:3306 kernel/workqueue.c:3390) 
[ 30.033967][ T9] ? lockdep_hardirqs_on_prepare (kernel/locking/lockdep.c:4299 kernel/locking/lockdep.c:4358) 
[ 30.034141][ T9] ? __pfx_worker_thread (kernel/workqueue.c:3339) 
[ 30.034278][ T9] ? __pfx_worker_thread (kernel/workqueue.c:3339) 
[ 30.034415][ T9] kthread (kernel/kthread.c:389) 
[ 30.034536][ T9] ? __pfx_kthread (kernel/kthread.c:342) 
[ 30.034670][ T9] ret_from_fork (arch/x86/kernel/process.c:147) 
[ 30.034812][ T9] ? __pfx_kthread (kernel/kthread.c:342) 


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