======================================
| xx__-> echo $?
| 0
| xx__-> [   36.276675][   T65] BUG: spinlock bad magic on CPU#3, kworker/3:2/65
| [ 36.276891][ T65] lock: noop_qdisc+0x240/0x300, .magic: 00000000, .owner: kworker/3:2/65, .owner_cpu: 3 
[   36.277366][   T65] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014
[   36.277683][   T65] Workqueue: mld mld_ifc_work
[   36.277838][   T65] Call Trace:
[   36.277950][   T65]  <TASK>
[ 36.278031][ T65] dump_stack_lvl (lib/dump_stack.c:122) 
[ 36.278181][ T65] do_raw_spin_unlock (kernel/locking/spinlock_debug.c:100 kernel/locking/spinlock_debug.c:141) 
[ 36.278329][ T65] _raw_spin_unlock (./arch/x86/include/asm/preempt.h:94 ./include/linux/spinlock_api_smp.h:143 kernel/locking/spinlock.c:186) 
[ 36.278478][ T65] __dev_xmit_skb (./include/net/sch_generic.h:226 ./include/net/sch_generic.h:217 net/core/dev.c:3879) 
[ 36.278633][ T65] ? __pfx___dev_xmit_skb (net/core/dev.c:3784) 
[ 36.278782][ T65] ? lockdep_hardirqs_on_prepare (kernel/locking/lockdep.c:4291 kernel/locking/lockdep.c:4358) 
[ 36.278962][ T65] __dev_queue_xmit (net/core/dev.c:4389) 
[ 36.279113][ T65] ? __lock_release (kernel/locking/lockdep.c:5435) 
[ 36.279255][ T65] ? ip6_finish_output2 (./include/net/neighbour.h:542 net/ipv6/ip6_output.c:137) 
[ 36.279404][ T65] ? __pfx___lock_release (kernel/locking/lockdep.c:5411) 
[ 36.279565][ T65] ? __pfx___dev_queue_xmit (net/core/dev.c:4332) 
[ 36.279710][ T65] ? mark_held_locks (kernel/locking/lockdep.c:4273) 
[ 36.279857][ T65] ? eth_header (net/ethernet/eth.c:100) 
[ 36.280003][ T65] ? neigh_resolve_output (./include/linux/netdevice.h:3159 net/core/neighbour.c:1560 net/core/neighbour.c:1545) 
[ 36.280153][ T65] ip6_finish_output2 (./include/net/neighbour.h:542 net/ipv6/ip6_output.c:137) 
[ 36.280298][ T65] ip6_finish_output (net/ipv6/ip6_output.c:211 net/ipv6/ip6_output.c:222) 
[ 36.280450][ T65] mld_sendpack (./include/net/dst.h:450 ./include/linux/netfilter.h:314 ./include/linux/netfilter.h:308 net/ipv6/mcast.c:1818) 
[ 36.280589][ T65] ? __pfx_mld_sendpack (net/ipv6/mcast.c:1779) 
[ 36.280735][ T65] ? mld_send_cr (net/ipv6/mcast.c:2096 (discriminator 11)) 
[ 36.280873][ T65] mld_ifc_work (net/ipv6/mcast.c:2652) 
[ 36.281024][ T65] process_one_work (kernel/workqueue.c:3231) 
[ 36.281173][ T65] ? __pfx___lock_release (kernel/locking/lockdep.c:5411) 
[ 36.281317][ T65] ? __pfx_process_one_work (kernel/workqueue.c:3133) 
[ 36.281465][ T65] ? assign_work (kernel/workqueue.c:1202) 
[ 36.281621][ T65] worker_thread (kernel/workqueue.c:3306 kernel/workqueue.c:3390) 
[ 36.281766][ T65] ? lockdep_hardirqs_on_prepare (kernel/locking/lockdep.c:4299 kernel/locking/lockdep.c:4358) 
[ 36.281948][ T65] ? __pfx_worker_thread (kernel/workqueue.c:3339) 
[ 36.282087][ T65] ? __pfx_worker_thread (kernel/workqueue.c:3339) 
[ 36.282233][ T65] kthread (kernel/kthread.c:389) 
[ 36.282345][ T65] ? __pfx_kthread (kernel/kthread.c:342) 
[ 36.282482][ T65] ret_from_fork (arch/x86/kernel/process.c:147) 
[ 36.282629][ T65] ? __pfx_kthread (kernel/kthread.c:342) 


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