======================================
| [ 13.447484][ C1] #4: ffff88800b9eb358 (&br->multicast_lock){+.-.}-{3:3}, at: br_multicast_port_query_expired (./include/trace/events/../../../net/bridge/br_private.h:1293 ./include/trace/events/../../../net/bridge/br_private.h:1302 net/bridge/br_multicast.c:1906) bridge 
| [ 13.448065][ C1] #5: ffffffff85b5b5c0 (rcu_read_lock_bh){....}-{1:3}, at: __dev_queue_xmit (./include/linux/bottom_half.h:20 ./include/linux/rcupdate.h:901 net/core/dev.c:4555) 
| [   13.448403][    C1]
| [   13.448403][    C1] stack backtrace:
[   13.448645][    C1] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   13.448647][    C1] Workqueue: events_unbound linkwatch_event
[   13.448653][    C1] Call Trace:
[   13.448655][    C1]  <IRQ>
[ 13.448658][ C1] dump_stack_lvl (lib/dump_stack.c:123) 
[ 13.448665][ C1] lockdep_rcu_suspicious (kernel/locking/lockdep.c:6848) 
[ 13.448676][ C1] dev_hard_start_xmit (./include/net/net_namespace.h:418 ./include/linux/netdevice.h:2695 net/core/dev.c:2466 net/core/dev.c:3772 net/core/dev.c:3793) 
[ 13.448687][ C1] __dev_queue_xmit (net/core/dev.h:340 net/core/dev.c:4631) 
[ 13.448697][ C1] ? __build_skb_around (./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:381 net/core/skbuff.c:439) 
[ 13.448708][ C1] ? __pfx___dev_queue_xmit (net/core/dev.c:4538) 
[ 13.448711][ C1] ? __pfx___alloc_skb (net/core/skbuff.c:642) 
[ 13.448717][ C1] ? stack_trace_save (kernel/stacktrace.c:123) 
[ 13.448723][ C1] ? __pfx_stack_trace_save (kernel/stacktrace.c:114) 
[ 13.448730][ C1] ? __pfx___br_multicast_query_handle_vlan (net/bridge/br_multicast.c:909) bridge 
[ 13.448782][ C1] br_dev_queue_push_xmit (net/bridge/br_forward.c:34) bridge 
[ 13.448815][ C1] ? __pfx_br_dev_queue_push_xmit (net/bridge/br_forward.c:34) bridge 
[ 13.448847][ C1] ? br_multicast_count (./arch/x86/include/asm/bitops.h:206 ./arch/x86/include/asm/bitops.h:238 ./include/asm-generic/bitops/instrumented-non-atomic.h:142 ./include/trace/events/../../../net/bridge/br_private.h:764 net/bridge/br_multicast.c:5052) bridge 
[ 13.448887][ C1] __br_multicast_send_query (net/bridge/br_multicast.c:1813) bridge 
[ 13.448932][ C1] ? __pfx___br_multicast_send_query (net/bridge/br_multicast.c:1789) bridge 
[ 13.448974][ C1] ? __lock_acquire (kernel/locking/lockdep.c:5228) 
[ 13.448985][ C1] ? br_multicast_send_query (net/bridge/br_multicast.c:1891) bridge 
[ 13.449019][ C1] br_multicast_send_query (net/bridge/br_multicast.c:1891) bridge 
[ 13.449058][ C1] ? __pfx_br_multicast_send_query (net/bridge/br_multicast.c:1852) bridge 
[ 13.449092][ C1] ? br_multicast_port_query_expired (./include/trace/events/../../../net/bridge/br_private.h:1293 ./include/trace/events/../../../net/bridge/br_private.h:1302 net/bridge/br_multicast.c:1906) bridge 
[ 13.449130][ C1] ? __pfx_br_ip4_multicast_port_query_expired (net/bridge/br_multicast.c:1920) bridge 
[ 13.449165][ C1] ? __pfx_lock_acquire.part.0 (kernel/locking/lockdep.c:5816) 
[ 13.449171][ C1] ? 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) 
[ 13.449176][ C1] ? __pfx_do_raw_spin_lock (kernel/locking/spinlock_debug.c:114) 
[ 13.449180][ C1] ? lock_acquire (kernel/locking/lockdep.c:5824) 
[ 13.449183][ C1] ? br_multicast_port_query_expired (./include/trace/events/../../../net/bridge/br_private.h:1293 ./include/trace/events/../../../net/bridge/br_private.h:1302 net/bridge/br_multicast.c:1906) bridge 
[ 13.449222][ C1] ? br_multicast_port_query_expired (net/bridge/br_multicast.c:1917) bridge 
[ 13.449255][ C1] ? __pfx_br_ip4_multicast_port_query_expired (net/bridge/br_multicast.c:1920) bridge 
[ 13.449289][ C1] br_multicast_port_query_expired (net/bridge/br_multicast.c:1917) bridge 
[ 13.449326][ C1] ? __pfx_br_ip4_multicast_port_query_expired (net/bridge/br_multicast.c:1920) bridge 
[ 13.449361][ C1] call_timer_fn (kernel/time/timer.c:1789) 
[ 13.449365][ C1] ? call_timer_fn (./include/linux/lockdep.h:31 kernel/time/timer.c:1779) 
[ 13.449368][ C1] ? call_timer_fn (./include/linux/lockdep.h:31 kernel/time/timer.c:1779) 
[ 13.449372][ C1] ? __pfx_call_timer_fn (kernel/time/timer.c:1766) 
[ 13.449376][ C1] ? 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:230) 
[ 13.449385][ C1] ? mark_held_locks (kernel/locking/lockdep.c:4323) 
[ 13.449397][ C1] __run_timers (kernel/time/timer.c:1841 kernel/time/timer.c:2414) 
[ 13.449401][ C1] ? __pfx_br_ip4_multicast_port_query_expired (net/bridge/br_multicast.c:1920) bridge 
[ 13.449443][ C1] ? __pfx___run_timers (kernel/time/timer.c:2385) 
[ 13.449452][ C1] ? 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) 
[ 13.449456][ C1] ? __pfx_do_raw_spin_lock (kernel/locking/spinlock_debug.c:114) 
[ 13.449460][ C1] ? lock_acquire (kernel/locking/lockdep.c:5824) 
[ 13.449463][ C1] ? run_timer_softirq (kernel/time/timer.c:2426 kernel/time/timer.c:2418 kernel/time/timer.c:2435 kernel/time/timer.c:2445) 
[ 13.449474][ C1] run_timer_softirq (kernel/time/timer.c:2427 kernel/time/timer.c:2418 kernel/time/timer.c:2435 kernel/time/timer.c:2445) 
[ 13.449479][ C1] handle_softirqs (kernel/softirq.c:561) 
[ 13.449488][ C1] ? br_device_event (net/bridge/br.c:97) bridge 
[ 13.449519][ C1] do_softirq (kernel/softirq.c:462 kernel/softirq.c:449) 
[   13.449523][    C1]  </IRQ>
[   13.449524][    C1]  <TASK>
[ 13.449525][ C1] __local_bh_enable_ip (kernel/softirq.c:389) 
[ 13.449530][ C1] br_device_event (net/bridge/br.c:97) bridge 
[ 13.449561][ C1] ? __pfx_br_device_event (net/bridge/br.c:29) bridge 
[ 13.449592][ C1] ? packet_notifier (net/packet/af_packet.c:4281) 
[ 13.449602][ C1] notifier_call_chain (kernel/notifier.c:85 (discriminator 2)) 
[ 13.449614][ C1] netdev_state_change (net/core/dev.c:1538 net/core/dev.c:1529) 
[ 13.449618][ C1] ? __pfx_netdev_state_change (net/core/dev.c:1530) 
[ 13.449634][ C1] linkwatch_do_dev (net/core/link_watch.c:186) 
[ 13.449638][ C1] __linkwatch_run_queue (./include/linux/spinlock.h:376 net/core/link_watch.c:245) 
[ 13.449645][ C1] ? __pfx___linkwatch_run_queue (net/core/link_watch.c:195) 
[ 13.449652][ C1] ? lock_acquire (kernel/locking/lockdep.c:5824) 
[ 13.449661][ C1] linkwatch_event (net/core/link_watch.c:287) 
[ 13.449664][ C1] process_one_work (kernel/workqueue.c:3238) 
[ 13.449677][ C1] ? __pfx___lock_release (kernel/locking/lockdep.c:5503) 
[ 13.449683][ C1] ? __pfx_process_one_work (kernel/workqueue.c:3140) 
[ 13.449696][ C1] ? assign_work (kernel/workqueue.c:1200) 
[ 13.449706][ C1] worker_thread (kernel/workqueue.c:3313 kernel/workqueue.c:3400) 
[ 13.449710][ C1] ? lockdep_hardirqs_on_prepare (kernel/locking/lockdep.c:4349 kernel/locking/lockdep.c:4408) 
[ 13.449722][ C1] ? __pfx_worker_thread (kernel/workqueue.c:3346) 
[ 13.449728][ C1] kthread (kernel/kthread.c:464) 
[ 13.449733][ C1] ? __pfx_kthread (kernel/kthread.c:413) 
[ 13.449741][ C1] ? __pfx_kthread (kernel/kthread.c:413) 
[ 13.449747][ C1] ret_from_fork (arch/x86/kernel/process.c:148) 
[ 13.449751][ C1] ? __pfx_kthread (kernel/kthread.c:413) 


Finger prints:
lockdep_rcu_suspicious:dev_hard_start_xmit:__dev_queue_xmit:br_dev_queue_push_xmit:__br_multicast_send_query