======================================
| [ 38.896629][ C2] ret_from_fork_asm (arch/x86/entry/entry_64.S:256) 
| [   38.896936][    C2]
| [   38.897026][    C2]
| [   38.897026][    C2] stack backtrace:
[   38.897527][    C2] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014
[   38.898188][    C2] Workqueue: ipv6_addrconf addrconf_dad_work
[   38.898427][    C2] Call Trace:
[   38.898571][    C2]  <IRQ>
[ 38.898672][ C2] dump_stack_lvl (lib/dump_stack.c:117) 
[ 38.898997][ C2] print_irq_inversion_bug.part.0 (kernel/locking/lockdep.c:4024) 
[ 38.899244][ C2] ? ret_from_fork_asm (arch/x86/entry/entry_64.S:256) 
[ 38.899432][ C2] ? __pfx_print_irq_inversion_bug.part.0 (kernel/locking/lockdep.c:4024) 
[ 38.899690][ C2] ? __pfx_usage_skip (kernel/locking/lockdep.c:2264) 
[ 38.899989][ C2] ? __pfx_usage_match (kernel/locking/lockdep.c:2256) 
[ 38.900169][ C2] ? arch_stack_walk (arch/x86/kernel/stacktrace.c:24) 
[ 38.900362][ C2] mark_lock_irq (kernel/locking/lockdep.c:4244) 
[ 38.900549][ C2] ? __pfx_mark_lock_irq (kernel/locking/lockdep.c:4207) 
[ 38.900871][ C2] ? stack_trace_save (kernel/stacktrace.c:123) 
[ 38.901053][ C2] ? save_trace (kernel/locking/lockdep.c:586) 
[ 38.901237][ C2] mark_lock (kernel/locking/lockdep.c:4678) 
[ 38.901378][ C2] mark_usage (kernel/locking/lockdep.c:4567) 
[ 38.901518][ C2] __lock_acquire (kernel/locking/lockdep.c:5091) 
[ 38.901833][ C2] lock_acquire.part.0 (kernel/locking/lockdep.c:467 kernel/locking/lockdep.c:5756) 
[ 38.902016][ C2] ? ipv6_get_lladdr (net/ipv6/addrconf.c:1911 net/ipv6/addrconf.c:1934) 
[ 38.902202][ C2] ? __pfx_lock_acquire.part.0 (kernel/locking/lockdep.c:5719) 
[ 38.902390][ C2] ? trace_lock_acquire (./include/trace/events/lock.h:24 (discriminator 52)) 
[ 38.902730][ C2] ? ipv6_get_lladdr (net/ipv6/addrconf.c:1911 net/ipv6/addrconf.c:1934) 
[ 38.902909][ C2] ? lock_acquire (kernel/locking/lockdep.c:5727) 
[ 38.903090][ C2] ? ipv6_get_lladdr (net/ipv6/addrconf.c:1911 net/ipv6/addrconf.c:1934) 
[ 38.903284][ C2] _raw_read_lock_bh (./include/linux/rwlock_api_smp.h:177 kernel/locking/spinlock.c:252) 
[ 38.903469][ C2] ? ipv6_get_lladdr (net/ipv6/addrconf.c:1911 net/ipv6/addrconf.c:1934) 
[ 38.903645][ C2] ipv6_get_lladdr (net/ipv6/addrconf.c:1911 net/ipv6/addrconf.c:1934) 
[ 38.903825][ C2] ndisc_send_ns (net/ipv6/ndisc.c:658) 
[ 38.904007][ C2] ? __pfx_ndisc_send_ns (net/ipv6/ndisc.c:653) 
[ 38.904208][ C2] ? __ipv6_chk_addr_and_flags (net/ipv6/addrconf.c:2009) 
[ 38.904437][ C2] ndisc_solicit (net/ipv6/ndisc.c:736) 
[ 38.904621][ C2] ? __pfx_ndisc_solicit (net/ipv6/ndisc.c:736) 
[ 38.904801][ C2] ? neigh_probe (net/core/neighbour.c:1074) 
[ 38.904993][ C2] neigh_probe (net/core/neighbour.c:1075) 
[ 38.905130][ C2] __neigh_event_send (net/core/neighbour.c:1242) 
[ 38.905314][ C2] neigh_resolve_output (net/core/neighbour.c:1547) 
[ 38.905518][ C2] ? __local_bh_enable_ip (./arch/x86/include/asm/irqflags.h:42 ./arch/x86/include/asm/irqflags.h:77 kernel/softirq.c:387) 
[ 38.905696][ C2] ? ___neigh_create (net/core/neighbour.c:722 (discriminator 9)) 
[ 38.906001][ C2] ip6_finish_output2 (./include/net/neighbour.h:542 net/ipv6/ip6_output.c:137) 
[ 38.906188][ C2] ip6_finish_output (net/ipv6/ip6_output.c:211 net/ipv6/ip6_output.c:222) 
[ 38.906386][ C2] ip6_output (./include/linux/netfilter.h:303 net/ipv6/ip6_output.c:243) 
[ 38.906523][ C2] ? __pfx_ip6_output (net/ipv6/ip6_output.c:230) 
[ 38.906830][ C2] ? pskb_expand_head (./arch/x86/include/asm/atomic.h:28 ./include/linux/atomic/atomic-arch-fallback.h:503 ./include/linux/atomic/atomic-instrumented.h:68 net/core/skbuff.c:2267) 
[ 38.907014][ C2] ? ip6_mtu (./include/linux/rcupdate.h:339 ./include/linux/rcupdate.h:814 ./include/net/ip6_route.h:336 net/ipv6/route.c:3217) 
[ 38.907148][ C2] ? ip6_local_out (net/ipv6/output_core.c:154) 
[ 38.907335][ C2] udp_tunnel6_xmit_skb (./include/net/ip6_tunnel.h:163 net/ipv6/ip6_udp_tunnel.c:111) ip6_udp_tunnel
[ 38.907570][ C2] vxlan_xmit_one (drivers/net/vxlan/vxlan_core.c:2551) vxlan
[ 38.907903][ C2] ? stack_access_ok (arch/x86/kernel/unwind_orc.c:396) 
[ 38.908085][ C2] ? ip6_fraglist_init (./include/linux/skbuff.h:2711 net/ipv6/ip6_output.c:715) 
[ 38.908266][ C2] ? __pfx_vxlan_xmit_one (drivers/net/vxlan/vxlan_core.c:2313) vxlan
[ 38.908507][ C2] ? __lock_acquire (kernel/locking/lockdep.c:5137) 
[ 38.908809][ C2] ? orc_sort_cmp (arch/x86/kernel/unwind_orc.c:80 arch/x86/kernel/unwind_orc.c:271) 
[ 38.909004][ C2] ? __dev_queue_xmit (./include/linux/bottom_half.h:20 ./include/linux/rcupdate.h:833 net/core/dev.c:4297) 
[ 38.909183][ C2] ? lock_acquire.part.0 (kernel/locking/lockdep.c:467 kernel/locking/lockdep.c:5756) 
[ 38.909387][ C2] ? vxlan_xmit (drivers/net/vxlan/vxlan_core.c:2766) vxlan
[ 38.909728][ C2] vxlan_xmit (drivers/net/vxlan/vxlan_core.c:2766) vxlan
[ 38.909923][ C2] dev_hard_start_xmit (./include/linux/netdevice.h:4875 ./include/linux/netdevice.h:4889 net/core/dev.c:3563 net/core/dev.c:3579) 
[ 38.910104][ C2] ? validate_xmit_skb.constprop.0 (net/core/dev.c:3634) 
[ 38.910337][ C2] __dev_queue_xmit (net/core/dev.h:167 net/core/dev.c:4373) 
[ 38.910531][ C2] ? find_held_lock (kernel/locking/lockdep.c:5244) 
[ 38.910715][ C2] ? __pfx___dev_queue_xmit (net/core/dev.c:4281) 
[ 38.910892][ C2] ? __lock_release (kernel/locking/lockdep.c:5430) 
[ 38.911071][ C2] ? __pfx___lock_release (kernel/locking/lockdep.c:5406) 
[ 38.911254][ C2] ? __pfx_lock_acquire.part.0 (kernel/locking/lockdep.c:5719) 
[ 38.911437][ C2] br_dev_queue_push_xmit (net/bridge/br_forward.c:34) bridge
[ 38.911699][ C2] ? __pfx_br_dev_queue_push_xmit (net/bridge/br_forward.c:34) bridge
[ 38.911960][ C2] ? __br_forward (./include/linux/netfilter.h:314 ./include/linux/netfilter.h:308 net/bridge/br_forward.c:115) bridge
[ 38.912324][ C2] deliver_clone (net/bridge/br_forward.c:132) bridge
[ 38.912546][ C2] br_handle_frame_finish (net/bridge/br_input.c:215) bridge
[ 38.912816][ C2] ? __pfx_br_handle_frame_finish (net/bridge/br_input.c:75) bridge
[ 38.913078][ 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:228) 
[ 38.913387][ C2] ? mark_lock (kernel/locking/lockdep.c:4656 (discriminator 3)) 
[ 38.913647][ C2] ? __pfx_validate_chain (kernel/locking/lockdep.c:3825) 
[ 38.913832][ C2] ? mark_lock (kernel/locking/lockdep.c:4656 (discriminator 3)) 
[ 38.913970][ C2] br_handle_frame (net/bridge/br_input.c:417) bridge
[ 38.914317][ C2] ? __pfx_br_handle_frame (net/bridge/br_input.c:321) bridge
[ 38.914581][ C2] __netif_receive_skb_core.constprop.0 (net/core/dev.c:5498) 
[ 38.914803][ C2] ? mark_lock (kernel/locking/lockdep.c:4656 (discriminator 3)) 
[ 38.914946][ C2] ? __lock_acquire (kernel/locking/lockdep.c:5137) 
[ 38.915250][ C2] ? __pfx___netif_receive_skb_core.constprop.0 (net/core/dev.c:5391) 
[ 38.915487][ C2] ? lock_acquire.part.0 (kernel/locking/lockdep.c:467 kernel/locking/lockdep.c:5756) 
[ 38.915664][ C2] ? process_backlog (./include/linux/rcupdate.h:329 ./include/linux/rcupdate.h:781 net/core/dev.c:6046) 
[ 38.915851][ C2] __netif_receive_skb_one_core (net/core/dev.c:5603) 
[ 38.916195][ C2] ? __pfx___netif_receive_skb_one_core (net/core/dev.c:5597) 
[ 38.916426][ C2] ? process_backlog (./include/linux/rcupdate.h:329 ./include/linux/rcupdate.h:781 net/core/dev.c:6046) 
[ 38.916605][ C2] ? lock_acquire (kernel/locking/lockdep.c:5727) 
[ 38.916790][ C2] ? process_backlog (./include/linux/rcupdate.h:329 ./include/linux/rcupdate.h:781 net/core/dev.c:6046) 
[ 38.917098][ C2] process_backlog (./include/linux/rcupdate.h:810 net/core/dev.c:6048) 
[ 38.917276][ C2] ? find_held_lock (kernel/locking/lockdep.c:5244) 
[ 38.917463][ C2] __napi_poll.constprop.0 (net/core/dev.c:6701) 
[ 38.917645][ C2] net_rx_action (net/core/dev.c:6770 net/core/dev.c:6886) 
[ 38.917951][ C2] ? __pfx_net_rx_action (net/core/dev.c:6850) 
[ 38.918135][ C2] ? usage_skip (kernel/locking/lockdep.c:2295 kernel/locking/lockdep.c:2263) 
[ 38.918314][ C2] ? mark_held_locks (kernel/locking/lockdep.c:4274) 
[ 38.918504][ C2] __do_softirq (kernel/softirq.c:554) 
[ 38.918682][ C2] ? __dev_queue_xmit (./include/linux/rcupdate.h:339 ./include/linux/rcupdate.h:849 net/core/dev.c:4399) 
[ 38.918990][ C2] do_softirq (kernel/softirq.c:455 kernel/softirq.c:442) 
[   38.919128][    C2]  </IRQ>
[   38.919225][    C2]  <TASK>
[ 38.919321][ C2] __local_bh_enable_ip (kernel/softirq.c:382) 
[ 38.919500][ C2] ? __dev_queue_xmit (./include/linux/rcupdate.h:339 ./include/linux/rcupdate.h:849 net/core/dev.c:4399) 
[ 38.919807][ C2] __dev_queue_xmit (net/core/dev.c:4400) 
[ 38.919995][ C2] ? mark_lock (kernel/locking/lockdep.c:4656 (discriminator 3)) 
[ 38.920139][ C2] ? trace_lock_acquire (./include/trace/events/lock.h:24 (discriminator 52)) 
[ 38.920330][ C2] ? mark_held_locks (kernel/locking/lockdep.c:4274) 
[ 38.920523][ C2] ? eth_header (net/ethernet/eth.c:100) 
[ 38.920860][ C2] ? __pfx___dev_queue_xmit (net/core/dev.c:4281) 
[ 38.921053][ C2] ip6_finish_output2 (./include/net/neighbour.h:542 net/ipv6/ip6_output.c:137) 
[ 38.921284][ C2] ip6_finish_output (net/ipv6/ip6_output.c:211 net/ipv6/ip6_output.c:222) 
[ 38.921475][ 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:228) 
[ 38.921786][ C2] ip6_output (./include/linux/netfilter.h:303 net/ipv6/ip6_output.c:243) 
[ 38.921930][ C2] ? __pfx_ip6_output (net/ipv6/ip6_output.c:230) 
[ 38.922119][ C2] ? lock_acquire.part.0 (kernel/locking/lockdep.c:5719) 
[ 38.922337][ C2] NF_HOOK.constprop.0 (./include/linux/rcupdate.h:329 ./include/linux/rcupdate.h:781 ./include/linux/netfilter.h:238 ./include/linux/netfilter.h:312) 
[ 38.922654][ C2] ? ndisc_send_skb (./include/linux/rcupdate.h:339 ./include/linux/rcupdate.h:814 net/ipv6/ndisc.c:455 net/ipv6/ndisc.c:503) 
[ 38.922893][ C2] ? __pfx_NF_HOOK.constprop.0 (./include/linux/netfilter.h:308) 
[ 38.923083][ C2] ? __pfx_lock_acquire.part.0 (kernel/locking/lockdep.c:5719) 
[ 38.923272][ C2] ? trace_lock_acquire (./include/trace/events/lock.h:24 (discriminator 52)) 
[ 38.923483][ C2] ndisc_send_skb (net/ipv6/ndisc.c:512 (discriminator 60)) 
[ 38.923792][ C2] ? __pfx_ndisc_send_skb (net/ipv6/ndisc.c:473) 
[ 38.924006][ C2] ndisc_send_ns (net/ipv6/ndisc.c:653) 
[ 38.924212][ C2] ? mark_lock (kernel/locking/lockdep.c:4656 (discriminator 3)) 
[ 38.924381][ C2] ? __pfx_ndisc_send_ns (net/ipv6/ndisc.c:653) 
[ 38.924696][ C2] ? mark_held_locks (kernel/locking/lockdep.c:4274) 
[ 38.924921][ C2] ? lockdep_hardirqs_on_prepare.part.0 (kernel/locking/lockdep.c:4300 kernel/locking/lockdep.c:4359) 
[ 38.925156][ C2] addrconf_dad_work (net/ipv6/addrconf.c:4280) 
[ 38.925371][ C2] ? __pfx_addrconf_dad_work (net/ipv6/addrconf.c:4178) 
[ 38.925684][ C2] ? process_one_work (kernel/workqueue.c:3230) 
[ 38.925873][ C2] ? lock_acquire (kernel/locking/lockdep.c:5727) 
[ 38.926061][ C2] ? process_one_work (kernel/workqueue.c:3230) 
[ 38.926249][ C2] process_one_work (kernel/workqueue.c:3254) 
[ 38.926613][ C2] ? __pfx___lock_release (kernel/locking/lockdep.c:5406) 
[ 38.926823][ C2] ? __pfx_process_one_work (kernel/workqueue.c:3156) 
[ 38.927038][ C2] ? assign_work (kernel/workqueue.c:1209) 
[ 38.927225][ C2] worker_thread (kernel/workqueue.c:3329 kernel/workqueue.c:3416) 
[ 38.927419][ C2] ? __pfx_worker_thread (kernel/workqueue.c:3362) 
[ 38.927605][ C2] kthread (kernel/kthread.c:388) 
[ 38.927741][ C2] ? __pfx_kthread (kernel/kthread.c:341) 
[ 38.927919][ C2] ret_from_fork (arch/x86/kernel/process.c:147) 
[ 38.928105][ C2] ? __pfx_kthread (kernel/kthread.c:341) 


Finger prints:
ret_from_fork_asm:dump_stack_lvl:mark_lock_irq:mark_lock