======================================
| [ 39.790681][ C3] ret_from_fork_asm (arch/x86/entry/entry_64.S:256) 
| [   39.790870][    C3]
| [   39.790977][    C3]
| [   39.790977][    C3] stack backtrace:
[   39.791781][    C3] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014
[   39.792242][    C3] Workqueue: ipv6_addrconf addrconf_dad_work
[   39.792489][    C3] Call Trace:
[   39.792643][    C3]  <IRQ>
[ 39.792741][ C3] dump_stack_lvl (lib/dump_stack.c:117) 
[ 39.793082][ C3] print_irq_inversion_bug.part.0 (kernel/locking/lockdep.c:4024) 
[ 39.793346][ C3] ? ret_from_fork_asm (arch/x86/entry/entry_64.S:256) 
[ 39.793544][ C3] ? __pfx_print_irq_inversion_bug.part.0 (kernel/locking/lockdep.c:4024) 
[ 39.793798][ C3] ? __pfx_usage_skip (kernel/locking/lockdep.c:2264) 
[ 39.794022][ C3] ? __pfx_usage_match (kernel/locking/lockdep.c:2256) 
[ 39.794248][ C3] ? arch_stack_walk (arch/x86/kernel/stacktrace.c:24) 
[ 39.794470][ C3] mark_lock_irq (kernel/locking/lockdep.c:4244) 
[ 39.794796][ C3] ? __pfx_mark_lock_irq (kernel/locking/lockdep.c:4207) 
[ 39.794986][ C3] ? stack_trace_save (kernel/stacktrace.c:123) 
[ 39.795201][ C3] ? save_trace (kernel/locking/lockdep.c:586) 
[ 39.795394][ C3] mark_lock (kernel/locking/lockdep.c:4678) 
[ 39.795534][ C3] mark_usage (kernel/locking/lockdep.c:4567) 
[ 39.795674][ C3] __lock_acquire (kernel/locking/lockdep.c:5091) 
[ 39.796054][ C3] lock_acquire.part.0 (kernel/locking/lockdep.c:467 kernel/locking/lockdep.c:5756) 
[ 39.796250][ C3] ? ipv6_get_lladdr (net/ipv6/addrconf.c:1911 net/ipv6/addrconf.c:1934) 
[ 39.796471][ C3] ? __pfx_lock_acquire.part.0 (kernel/locking/lockdep.c:5719) 
[ 39.796661][ C3] ? trace_lock_acquire (./include/trace/events/lock.h:24 (discriminator 52)) 
[ 39.796852][ C3] ? ipv6_get_lladdr (net/ipv6/addrconf.c:1911 net/ipv6/addrconf.c:1934) 
[ 39.797037][ C3] ? lock_acquire (kernel/locking/lockdep.c:5727) 
[ 39.797217][ C3] ? ipv6_get_lladdr (net/ipv6/addrconf.c:1911 net/ipv6/addrconf.c:1934) 
[ 39.797401][ C3] _raw_read_lock_bh (./include/linux/rwlock_api_smp.h:177 kernel/locking/spinlock.c:252) 
[ 39.797593][ C3] ? ipv6_get_lladdr (net/ipv6/addrconf.c:1911 net/ipv6/addrconf.c:1934) 
[ 39.797926][ C3] ipv6_get_lladdr (net/ipv6/addrconf.c:1911 net/ipv6/addrconf.c:1934) 
[ 39.798120][ C3] ndisc_send_ns (net/ipv6/ndisc.c:658) 
[ 39.798310][ C3] ? __pfx_ndisc_send_ns (net/ipv6/ndisc.c:653) 
[ 39.798500][ C3] ? __ipv6_chk_addr_and_flags (net/ipv6/addrconf.c:2009) 
[ 39.798762][ C3] ndisc_solicit (net/ipv6/ndisc.c:736) 
[ 39.798956][ C3] ? __pfx_ndisc_solicit (net/ipv6/ndisc.c:736) 
[ 39.799145][ C3] ? neigh_probe (net/core/neighbour.c:1074) 
[ 39.799330][ C3] neigh_probe (net/core/neighbour.c:1075) 
[ 39.799477][ C3] __neigh_event_send (net/core/neighbour.c:1242) 
[ 39.799685][ C3] neigh_resolve_output (net/core/neighbour.c:1547) 
[ 39.799896][ C3] ? __local_bh_enable_ip (./arch/x86/include/asm/irqflags.h:42 ./arch/x86/include/asm/irqflags.h:77 kernel/softirq.c:387) 
[ 39.800085][ C3] ? ___neigh_create (net/core/neighbour.c:722 (discriminator 9)) 
[ 39.800284][ C3] ip6_finish_output2 (./include/net/neighbour.h:542 net/ipv6/ip6_output.c:137) 
[ 39.800472][ C3] ip6_finish_output (net/ipv6/ip6_output.c:211 net/ipv6/ip6_output.c:222) 
[ 39.800652][ C3] ip6_output (./include/linux/netfilter.h:303 net/ipv6/ip6_output.c:243) 
[ 39.800806][ C3] ? __pfx_ip6_output (net/ipv6/ip6_output.c:230) 
[ 39.800985][ C3] ? 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) 
[ 39.801302][ C3] ? ip6_mtu (./include/linux/rcupdate.h:339 ./include/linux/rcupdate.h:814 ./include/net/ip6_route.h:336 net/ipv6/route.c:3217) 
[ 39.801447][ C3] ? ip6_local_out (net/ipv6/output_core.c:154) 
[ 39.801634][ C3] udp_tunnel6_xmit_skb (./include/net/ip6_tunnel.h:163 net/ipv6/ip6_udp_tunnel.c:111) ip6_udp_tunnel
[ 39.801873][ C3] vxlan_xmit_one (drivers/net/vxlan/vxlan_core.c:2551) vxlan
[ 39.802193][ C3] ? stack_access_ok (arch/x86/kernel/unwind_orc.c:396) 
[ 39.802386][ C3] ? ip6_fraglist_init (./include/linux/skbuff.h:2711 net/ipv6/ip6_output.c:715) 
[ 39.802576][ C3] ? __pfx_vxlan_xmit_one (drivers/net/vxlan/vxlan_core.c:2313) vxlan
[ 39.802841][ C3] ? __lock_acquire (kernel/locking/lockdep.c:5137) 
[ 39.803147][ C3] ? orc_sort_cmp (arch/x86/kernel/unwind_orc.c:80 arch/x86/kernel/unwind_orc.c:271) 
[ 39.803336][ C3] ? __dev_queue_xmit (./include/linux/bottom_half.h:20 ./include/linux/rcupdate.h:833 net/core/dev.c:4297) 
[ 39.803522][ C3] ? lock_acquire.part.0 (kernel/locking/lockdep.c:467 kernel/locking/lockdep.c:5756) 
[ 39.803718][ C3] ? vxlan_xmit (drivers/net/vxlan/vxlan_core.c:2766) vxlan
[ 39.803942][ C3] vxlan_xmit (drivers/net/vxlan/vxlan_core.c:2766) vxlan
[ 39.804415][ C3] dev_hard_start_xmit (./include/linux/netdevice.h:4875 ./include/linux/netdevice.h:4889 net/core/dev.c:3563 net/core/dev.c:3579) 
[ 39.804620][ C3] ? validate_xmit_skb.constprop.0 (net/core/dev.c:3634) 
[ 39.804850][ C3] __dev_queue_xmit (net/core/dev.h:167 net/core/dev.c:4373) 
[ 39.805040][ C3] ? find_held_lock (kernel/locking/lockdep.c:5244) 
[ 39.805346][ C3] ? __pfx___dev_queue_xmit (net/core/dev.c:4281) 
[ 39.805535][ C3] ? __lock_release (kernel/locking/lockdep.c:5430) 
[ 39.805722][ C3] ? __pfx___lock_release (kernel/locking/lockdep.c:5406) 
[ 39.805906][ C3] ? __pfx_lock_acquire.part.0 (kernel/locking/lockdep.c:5719) 
[ 39.806210][ C3] br_dev_queue_push_xmit (net/bridge/br_forward.c:34) bridge
[ 39.806471][ C3] ? __pfx_br_dev_queue_push_xmit (net/bridge/br_forward.c:34) bridge
[ 39.806729][ C3] ? __br_forward (./include/linux/netfilter.h:314 ./include/linux/netfilter.h:308 net/bridge/br_forward.c:115) bridge
[ 39.806945][ C3] deliver_clone (net/bridge/br_forward.c:132) bridge
[ 39.807287][ C3] br_handle_frame_finish (net/bridge/br_input.c:215) bridge
[ 39.807552][ C3] ? __pfx_br_handle_frame_finish (net/bridge/br_input.c:75) bridge
[ 39.807835][ C3] ? 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) 
[ 39.808141][ C3] ? mark_lock (kernel/locking/lockdep.c:4656 (discriminator 3)) 
[ 39.808286][ C3] br_handle_frame (net/bridge/br_input.c:417) bridge
[ 39.808507][ C3] ? __pfx_br_handle_frame (net/bridge/br_input.c:321) bridge
[ 39.808811][ C3] __netif_receive_skb_core.constprop.0 (net/core/dev.c:5498) 
[ 39.809173][ C3] ? mark_lock (kernel/locking/lockdep.c:4656 (discriminator 3)) 
[ 39.809323][ C3] ? __lock_acquire (kernel/locking/lockdep.c:5137) 
[ 39.809521][ C3] ? __pfx___netif_receive_skb_core.constprop.0 (net/core/dev.c:5391) 
[ 39.809806][ C3] ? lock_acquire.part.0 (kernel/locking/lockdep.c:467 kernel/locking/lockdep.c:5756) 
[ 39.810001][ C3] ? process_backlog (./include/linux/rcupdate.h:329 ./include/linux/rcupdate.h:781 net/core/dev.c:6046) 
[ 39.810331][ C3] __netif_receive_skb_one_core (net/core/dev.c:5603) 
[ 39.810582][ C3] ? __pfx___netif_receive_skb_one_core (net/core/dev.c:5597) 
[ 39.810836][ C3] ? process_backlog (./include/linux/rcupdate.h:329 ./include/linux/rcupdate.h:781 net/core/dev.c:6046) 
[ 39.811163][ C3] ? lock_acquire (kernel/locking/lockdep.c:5727) 
[ 39.811368][ C3] ? process_backlog (./include/linux/rcupdate.h:329 ./include/linux/rcupdate.h:781 net/core/dev.c:6046) 
[ 39.811576][ C3] process_backlog (./include/linux/rcupdate.h:810 net/core/dev.c:6048) 
[ 39.811780][ C3] ? find_held_lock (kernel/locking/lockdep.c:5244) 
[ 39.811985][ C3] __napi_poll.constprop.0 (net/core/dev.c:6701) 
[ 39.812301][ C3] net_rx_action (net/core/dev.c:6770 net/core/dev.c:6886) 
[ 39.812502][ C3] ? __pfx_net_rx_action (net/core/dev.c:6850) 
[ 39.812686][ C3] ? usage_skip (kernel/locking/lockdep.c:2295 kernel/locking/lockdep.c:2263) 
[ 39.812876][ C3] ? mark_held_locks (kernel/locking/lockdep.c:4274) 
[ 39.813200][ C3] __do_softirq (kernel/softirq.c:554) 
[ 39.813410][ C3] ? __dev_queue_xmit (./include/linux/rcupdate.h:339 ./include/linux/rcupdate.h:849 net/core/dev.c:4399) 
[ 39.813600][ C3] do_softirq (kernel/softirq.c:455 kernel/softirq.c:442) 
[   39.813749][    C3]  </IRQ>
[   39.813871][    C3]  <TASK>
[ 39.814113][ C3] __local_bh_enable_ip (kernel/softirq.c:382) 
[ 39.814310][ C3] ? __dev_queue_xmit (./include/linux/rcupdate.h:339 ./include/linux/rcupdate.h:849 net/core/dev.c:4399) 
[ 39.814523][ C3] __dev_queue_xmit (net/core/dev.c:4400) 
[ 39.814716][ C3] ? mark_lock (kernel/locking/lockdep.c:4656 (discriminator 3)) 
[ 39.814859][ C3] ? trace_lock_acquire (./include/trace/events/lock.h:24 (discriminator 52)) 
[ 39.815177][ C3] ? mark_held_locks (kernel/locking/lockdep.c:4274) 
[ 39.815367][ C3] ? eth_header (net/ethernet/eth.c:100) 
[ 39.815552][ C3] ? __pfx___dev_queue_xmit (net/core/dev.c:4281) 
[ 39.815749][ C3] ip6_finish_output2 (./include/net/neighbour.h:542 net/ipv6/ip6_output.c:137) 
[ 39.816100][ C3] ip6_finish_output (net/ipv6/ip6_output.c:211 net/ipv6/ip6_output.c:222) 
[ 39.816294][ C3] ? 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) 
[ 39.816482][ C3] ip6_output (./include/linux/netfilter.h:303 net/ipv6/ip6_output.c:243) 
[ 39.816622][ C3] ? __pfx_ip6_output (net/ipv6/ip6_output.c:230) 
[ 39.816818][ C3] ? lock_acquire.part.0 (kernel/locking/lockdep.c:5719) 
[ 39.817137][ C3] NF_HOOK.constprop.0 (./include/linux/rcupdate.h:329 ./include/linux/rcupdate.h:781 ./include/linux/netfilter.h:238 ./include/linux/netfilter.h:312) 
[ 39.817338][ C3] ? ndisc_send_skb (./include/linux/rcupdate.h:339 ./include/linux/rcupdate.h:814 net/ipv6/ndisc.c:455 net/ipv6/ndisc.c:503) 
[ 39.817520][ C3] ? __pfx_NF_HOOK.constprop.0 (./include/linux/netfilter.h:308) 
[ 39.817704][ C3] ? __pfx_lock_acquire.part.0 (kernel/locking/lockdep.c:5719) 
[ 39.817900][ C3] ? trace_lock_acquire (./include/trace/events/lock.h:24 (discriminator 52)) 
[ 39.818082][ C3] ndisc_send_skb (net/ipv6/ndisc.c:512 (discriminator 60)) 
[ 39.818265][ C3] ? __pfx_ndisc_send_skb (net/ipv6/ndisc.c:473) 
[ 39.818456][ C3] ndisc_send_ns (net/ipv6/ndisc.c:653) 
[ 39.818775][ C3] ? mark_lock (kernel/locking/lockdep.c:4656 (discriminator 3)) 
[ 39.818912][ C3] ? __pfx_ndisc_send_ns (net/ipv6/ndisc.c:653) 
[ 39.819100][ C3] ? mark_held_locks (kernel/locking/lockdep.c:4274) 
[ 39.819282][ C3] ? lockdep_hardirqs_on_prepare.part.0 (kernel/locking/lockdep.c:4300 kernel/locking/lockdep.c:4359) 
[ 39.819765][ C3] addrconf_dad_work (net/ipv6/addrconf.c:4280) 
[ 39.819966][ C3] ? __pfx_addrconf_dad_work (net/ipv6/addrconf.c:4178) 
[ 39.820166][ C3] ? process_one_work (kernel/workqueue.c:3230) 
[ 39.820363][ C3] ? lock_acquire (kernel/locking/lockdep.c:5727) 
[ 39.820554][ C3] ? process_one_work (kernel/workqueue.c:3230) 
[ 39.820862][ C3] process_one_work (kernel/workqueue.c:3254) 
[ 39.821046][ C3] ? __pfx___lock_release (kernel/locking/lockdep.c:5406) 
[ 39.821248][ C3] ? __pfx_process_one_work (kernel/workqueue.c:3156) 
[ 39.821456][ C3] ? assign_work (kernel/workqueue.c:1209) 
[ 39.821807][ C3] worker_thread (kernel/workqueue.c:3329 kernel/workqueue.c:3416) 
[ 39.822002][ C3] ? lockdep_hardirqs_on_prepare.part.0 (kernel/locking/lockdep.c:4300 kernel/locking/lockdep.c:4359) 
[ 39.822238][ C3] ? __pfx_worker_thread (kernel/workqueue.c:3362) 
[ 39.822435][ C3] ? __pfx_worker_thread (kernel/workqueue.c:3362) 
[ 39.822760][ C3] kthread (kernel/kthread.c:388) 
[ 39.822906][ C3] ? __pfx_kthread (kernel/kthread.c:341) 
[ 39.823093][ C3] ret_from_fork (arch/x86/kernel/process.c:147) 
[ 39.823295][ C3] ? __pfx_kthread (kernel/kthread.c:341) 


Finger prints:
ret_from_fork_asm:dump_stack_lvl:mark_lock_irq:mark_lock