======================================
| xx__-> echo $?
| 0
| xx__-> [   88.376064][    C2] BUG: spinlock bad magic on CPU#2, swapper/2/0
| [ 88.376290][ C2] lock: noop_qdisc+0x240/0x300, .magic: 00000000, .owner: swapper/2/0, .owner_cpu: 2 
[   88.376791][    C2] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014
[   88.377114][    C2] Call Trace:
[   88.377231][    C2]  <IRQ>
[ 88.377317][ C2] dump_stack_lvl (lib/dump_stack.c:122) 
[ 88.377470][ C2] do_raw_spin_unlock (kernel/locking/spinlock_debug.c:100 kernel/locking/spinlock_debug.c:141) 
[ 88.377623][ C2] _raw_spin_unlock (./arch/x86/include/asm/preempt.h:94 ./include/linux/spinlock_api_smp.h:143 kernel/locking/spinlock.c:186) 
[ 88.377774][ C2] __dev_xmit_skb (./include/net/sch_generic.h:226 ./include/net/sch_generic.h:217 net/core/dev.c:3879) 
[ 88.377925][ C2] ? __pfx___dev_xmit_skb (net/core/dev.c:3784) 
[ 88.378068][ C2] ? __dev_queue_xmit (./include/linux/bottom_half.h:20 ./include/linux/rcupdate.h:890 net/core/dev.c:4348) 
[ 88.378223][ C2] ? lock_acquire (kernel/locking/lockdep.c:5732) 
[ 88.378369][ C2] ? __dev_queue_xmit (./include/linux/bottom_half.h:20 ./include/linux/rcupdate.h:890 net/core/dev.c:4348) 
[ 88.378508][ C2] __dev_queue_xmit (net/core/dev.c:4389) 
[ 88.378659][ C2] ? __lock_release (kernel/locking/lockdep.c:5435) 
[ 88.378796][ C2] ? ip6_finish_output2 (./include/net/neighbour.h:542 net/ipv6/ip6_output.c:137) 
[ 88.378944][ C2] ? __pfx___lock_release (kernel/locking/lockdep.c:5411) 
[ 88.379084][ C2] ? __pfx___dev_queue_xmit (net/core/dev.c:4332) 
[ 88.379221][ C2] ? mark_held_locks (kernel/locking/lockdep.c:4273) 
[ 88.379368][ C2] ? eth_header (net/ethernet/eth.c:100) 
[ 88.379512][ C2] ? neigh_resolve_output (./include/linux/netdevice.h:3159 net/core/neighbour.c:1560 net/core/neighbour.c:1545) 
[ 88.379672][ C2] ip6_finish_output2 (./include/net/neighbour.h:542 net/ipv6/ip6_output.c:137) 
[ 88.379813][ C2] ip6_finish_output (net/ipv6/ip6_output.c:211 net/ipv6/ip6_output.c:222) 
[ 88.379956][ C2] ? ip6_local_out (net/ipv6/output_core.c:154) 
[ 88.380129][ C2] ip6_send_skb (net/ipv6/ip6_output.c:1960) 
[ 88.380270][ C2] icmp6_send (net/ipv6/icmp.c:624) 
[ 88.380414][ C2] ? __pfx_icmp6_send (net/ipv6/icmp.c:448) 
[ 88.380558][ C2] ? __pfx_validate_chain (kernel/locking/lockdep.c:3824) 
[ 88.380698][ C2] ? hlock_class (./arch/x86/include/asm/bitops.h:227 ./arch/x86/include/asm/bitops.h:239 ./include/asm-generic/bitops/instrumented-non-atomic.h:142 kernel/locking/lockdep.c:227) 
[ 88.380853][ C2] ? __pfx___lock_release (kernel/locking/lockdep.c:5411) 
[ 88.381000][ C2] ? lock_acquire.part.0 (kernel/locking/lockdep.c:466 kernel/locking/lockdep.c:5761) 
[ 88.381145][ C2] ? ip6_link_failure (./include/linux/skbuff.h:1141 net/ipv6/route.c:2801) 
[ 88.381285][ C2] ip6_link_failure (./include/linux/skbuff.h:1141 net/ipv6/route.c:2801) 
[ 88.381426][ C2] ndisc_error_report (./include/net/dst.h:429 net/ipv6/ndisc.c:731) 
[ 88.381574][ C2] neigh_invalidate (net/core/neighbour.c:1061) 
[ 88.381715][ C2] neigh_timer_handler (net/core/neighbour.c:1162 (discriminator 2)) 
[ 88.381859][ C2] ? __pfx_neigh_timer_handler (net/core/neighbour.c:1085) 
[ 88.382002][ C2] call_timer_fn (kernel/time/timer.c:1792) 
[ 88.382146][ C2] ? call_timer_fn (./include/linux/lockdep.h:31 kernel/time/timer.c:1782) 
[ 88.382284][ C2] ? call_timer_fn (./include/linux/lockdep.h:31 kernel/time/timer.c:1782) 
[ 88.382421][ C2] ? __pfx_call_timer_fn (kernel/time/timer.c:1769) 
[ 88.382559][ C2] ? mark_lock (kernel/locking/lockdep.c:4655 (discriminator 3)) 
[ 88.382670][ C2] __run_timers (kernel/time/timer.c:1844 kernel/time/timer.c:2417) 
[ 88.382807][ C2] ? __pfx_neigh_timer_handler (net/core/neighbour.c:1085) 
[ 88.382950][ C2] ? __pfx___run_timers (kernel/time/timer.c:2388) 
[ 88.383090][ C2] ? do_raw_spin_lock (./arch/x86/include/asm/atomic.h:107 ./include/linux/atomic/atomic-arch-fallback.h:2170 ./include/linux/atomic/atomic-instrumented.h:1302 ./include/asm-generic/qspinlock.h:111 kernel/locking/spinlock_debug.c:116) 
[ 88.383236][ C2] ? __pfx_do_raw_spin_lock (kernel/locking/spinlock_debug.c:114) 
[ 88.383374][ C2] ? lock_acquire (kernel/locking/lockdep.c:5732) 
[ 88.383523][ C2] ? run_timer_softirq (kernel/time/timer.c:2428 kernel/time/timer.c:2421 kernel/time/timer.c:2437 kernel/time/timer.c:2447) 
[ 88.383667][ C2] run_timer_softirq (kernel/time/timer.c:2429 kernel/time/timer.c:2421 kernel/time/timer.c:2437 kernel/time/timer.c:2447) 
[ 88.383821][ C2] handle_softirqs (kernel/softirq.c:554) 
[ 88.383969][ C2] irq_exit_rcu (kernel/softirq.c:589 kernel/softirq.c:428 kernel/softirq.c:637 kernel/softirq.c:649) 
[ 88.384083][ C2] sysvec_apic_timer_interrupt (arch/x86/kernel/apic/apic.c:1043 arch/x86/kernel/apic/apic.c:1043) 
[   88.384227][    C2]  </IRQ>
[   88.384305][    C2]  <TASK>
[ 88.384379][ C2] asm_sysvec_apic_timer_interrupt (./arch/x86/include/asm/idtentry.h:702) 
[ 88.384578][ C2] RIP: 0010:default_idle (./arch/x86/include/asm/irqflags.h:37 ./arch/x86/include/asm/irqflags.h:92 arch/x86/kernel/process.c:743) 
[ 88.384726][ C2] Code: 4c 01 c7 4c 29 c2 e9 72 ff ff ff 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 0f 00 2d e3 e9 46 00 fb f4 <fa> c3 cc cc cc cc 66 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90
All code
========
   0:	4c 01 c7             	add    %r8,%rdi
   3:	4c 29 c2             	sub    %r8,%rdx
   6:	e9 72 ff ff ff       	jmp    0xffffffffffffff7d
   b:	90                   	nop
   c:	90                   	nop
   d:	90                   	nop
   e:	90                   	nop
   f:	90                   	nop
  10:	90                   	nop
  11:	90                   	nop
  12:	90                   	nop
  13:	90                   	nop
  14:	90                   	nop
  15:	90                   	nop
  16:	90                   	nop
  17:	90                   	nop
  18:	90                   	nop
  19:	90                   	nop
  1a:	90                   	nop
  1b:	f3 0f 1e fa          	endbr64
  1f:	66 90                	xchg   %ax,%ax
  21:	0f 00 2d e3 e9 46 00 	verw   0x46e9e3(%rip)        # 0x46ea0b
  28:	fb                   	sti
  29:	f4                   	hlt
  2a:*	fa                   	cli		<-- trapping instruction
  2b:	c3                   	ret
  2c:	cc                   	int3
  2d:	cc                   	int3
  2e:	cc                   	int3
  2f:	cc                   	int3
  30:	66 66 2e 0f 1f 84 00 	data16 cs nopw 0x0(%rax,%rax,1)
  37:	00 00 00 00 
  3b:	90                   	nop
  3c:	90                   	nop
  3d:	90                   	nop
  3e:	90                   	nop
  3f:	90                   	nop

Code starting with the faulting instruction
===========================================
   0:	fa                   	cli
   1:	c3                   	ret
   2:	cc                   	int3
   3:	cc                   	int3
   4:	cc                   	int3
   5:	cc                   	int3
   6:	66 66 2e 0f 1f 84 00 	data16 cs nopw 0x0(%rax,%rax,1)
   d:	00 00 00 00 
  11:	90                   	nop
  12:	90                   	nop
  13:	90                   	nop
  14:	90                   	nop
  15:	90                   	nop
[   88.385237][    C2] RSP: 0018:ffffc9000016fdf8 EFLAGS: 00000246
[   88.385420][    C2] RAX: 00000000002a0047 RBX: 1ffff9200002dfc1 RCX: ffffffffa5df2795
[   88.385647][    C2] RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffffa36a6984
[   88.385859][    C2] RBP: 0000000000000000 R08: 0000000000000001 R09: ffffed1005ee70a0
[   88.386075][    C2] R10: ffff88802f738503 R11: ffff88802f72d9f0 R12: 0000000000000000
[   88.386289][    C2] R13: ffff888001ba8040 R14: dffffc0000000000 R15: 0000000000000000
[ 88.386497][ C2] ? ct_kernel_exit.constprop.0 (kernel/context_tracking.c:147) 
[ 88.386640][ C2] ? cpuidle_idle_call (kernel/sched/idle.c:186) 
[ 88.386789][ C2] default_idle_call (./include/linux/cpuidle.h:143 kernel/sched/idle.c:118) 
[ 88.386930][ C2] cpuidle_idle_call (kernel/sched/idle.c:186) 
[ 88.387080][ C2] ? __pfx_cpuidle_idle_call (kernel/sched/idle.c:168) 
[ 88.387222][ C2] ? tsc_verify_tsc_adjust (arch/x86/kernel/tsc_sync.c:59) 
[ 88.387369][ C2] do_idle (kernel/sched/idle.c:326) 
[ 88.387476][ C2] cpu_startup_entry (kernel/sched/idle.c:423 (discriminator 1)) 
[ 88.387617][ C2] start_secondary (arch/x86/kernel/smpboot.c:201 arch/x86/kernel/smpboot.c:281) 
[ 88.387763][ C2] ? __pfx_start_secondary (arch/x86/kernel/smpboot.c:231) 


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