======================================
| xx__-> [   26.409778][  T267] ip (267) used greatest stack depth: 24448 bytes left
| [   26.935876][  T275] ip (275) used greatest stack depth: 23776 bytes left
| [   29.208853][   T63] BUG: spinlock bad magic on CPU#3, kworker/3:2/63
| [ 29.209087][ T63] lock: noop_qdisc+0x240/0x300, .magic: 00000000, .owner: kworker/3:2/63, .owner_cpu: 3 
[   29.209610][   T63] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014
[   29.209952][   T63] Workqueue: mld mld_ifc_work
[   29.210115][   T63] Call Trace:
[   29.210232][   T63]  <TASK>
[ 29.210312][ T63] dump_stack_lvl (lib/dump_stack.c:122) 
[ 29.210466][ T63] do_raw_spin_unlock (kernel/locking/spinlock_debug.c:100 kernel/locking/spinlock_debug.c:141) 
[ 29.210623][ T63] _raw_spin_unlock (./arch/x86/include/asm/preempt.h:94 ./include/linux/spinlock_api_smp.h:143 kernel/locking/spinlock.c:186) 
[ 29.210777][ T63] __dev_xmit_skb (./include/net/sch_generic.h:226 ./include/net/sch_generic.h:217 net/core/dev.c:3879) 
[ 29.210935][ T63] ? __pfx___dev_xmit_skb (net/core/dev.c:3784) 
[ 29.211085][ T63] ? lockdep_hardirqs_on_prepare (kernel/locking/lockdep.c:4291 kernel/locking/lockdep.c:4358) 
[ 29.211280][ T63] __dev_queue_xmit (net/core/dev.c:4389) 
[ 29.211442][ T63] ? __lock_release (kernel/locking/lockdep.c:5435) 
[ 29.211594][ T63] ? ip6_finish_output2 (./include/net/neighbour.h:542 net/ipv6/ip6_output.c:137) 
[ 29.211752][ T63] ? __pfx___lock_release (kernel/locking/lockdep.c:5411) 
[ 29.211901][ T63] ? __pfx___dev_queue_xmit (net/core/dev.c:4332) 
[ 29.212057][ T63] ? mark_held_locks (kernel/locking/lockdep.c:4273) 
[ 29.212211][ T63] ? eth_header (net/ethernet/eth.c:100) 
[ 29.212365][ T63] ? neigh_resolve_output (./include/linux/netdevice.h:3159 net/core/neighbour.c:1560 net/core/neighbour.c:1545) 
[ 29.212518][ T63] ip6_finish_output2 (./include/net/neighbour.h:542 net/ipv6/ip6_output.c:137) 
[ 29.212683][ T63] ip6_finish_output (net/ipv6/ip6_output.c:211 net/ipv6/ip6_output.c:222) 
[ 29.212835][ T63] ip6_output (./include/linux/netfilter.h:303 net/ipv6/ip6_output.c:243) 
[ 29.212948][ T63] ? __pfx_ip6_output (net/ipv6/ip6_output.c:230) 
[ 29.213102][ T63] ? lock_acquire.part.0 (kernel/locking/lockdep.c:466 kernel/locking/lockdep.c:5761) 
[ 29.213253][ T63] ? find_held_lock (kernel/locking/lockdep.c:5249) 
[ 29.213412][ T63] ? __lock_release (kernel/locking/lockdep.c:5435) 
[ 29.213565][ T63] ? icmp6_dst_alloc (net/ipv6/route.c:3295) 
[ 29.213720][ T63] NF_HOOK.constprop.0 (./include/linux/rcupdate.h:326 ./include/linux/rcupdate.h:838 ./include/linux/netfilter.h:238 ./include/linux/netfilter.h:312) 
[ 29.213871][ T63] ? __pfx_NF_HOOK.constprop.0 (./include/linux/netfilter.h:308) 
[ 29.214026][ T63] ? __pfx_xfrm_lookup_with_ifid (net/xfrm/xfrm_policy.c:3140) 
[ 29.214215][ T63] ? lockdep_hardirqs_on_prepare (kernel/locking/lockdep.c:4299 kernel/locking/lockdep.c:4358) 
[ 29.214401][ T63] ? icmp6_dst_alloc (net/ipv6/route.c:3295) 
[ 29.214554][ T63] ? __local_bh_enable_ip (./arch/x86/include/asm/irqflags.h:42 ./arch/x86/include/asm/irqflags.h:97 kernel/softirq.c:387) 
[ 29.214707][ T63] mld_sendpack (net/ipv6/mcast.c:1822) 
[ 29.214861][ T63] ? __pfx_mld_sendpack (net/ipv6/mcast.c:1779) 
[ 29.215020][ T63] ? mld_send_cr (net/ipv6/mcast.c:2096 (discriminator 11)) 
[ 29.215177][ T63] mld_ifc_work (net/ipv6/mcast.c:2652) 
[ 29.215331][ T63] process_one_work (kernel/workqueue.c:3231) 
[ 29.215491][ T63] ? __pfx___lock_release (kernel/locking/lockdep.c:5411) 
[ 29.215645][ T63] ? __pfx_process_one_work (kernel/workqueue.c:3133) 
[ 29.215797][ T63] ? assign_work (kernel/workqueue.c:1202) 
[ 29.215957][ T63] worker_thread (kernel/workqueue.c:3306 kernel/workqueue.c:3390) 
[ 29.216109][ T63] ? lockdep_hardirqs_on_prepare (kernel/locking/lockdep.c:4299 kernel/locking/lockdep.c:4358) 
[ 29.216310][ T63] ? __pfx_worker_thread (kernel/workqueue.c:3339) 
[ 29.216467][ T63] ? __pfx_worker_thread (kernel/workqueue.c:3339) 
[ 29.216621][ T63] kthread (kernel/kthread.c:389) 
[ 29.216742][ T63] ? __pfx_kthread (kernel/kthread.c:342) 
[ 29.216895][ T63] ret_from_fork (arch/x86/kernel/process.c:147) 
[ 29.217048][ T63] ? __pfx_kthread (kernel/kthread.c:342) 


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