======================================
| [ 29.384544][ T63] #1: ffffc90000447d40 ((work_completion)(&port->wq)){+.+.}-{0:0}, at: process_one_work (kernel/workqueue.c:3214) 
| [ 29.384849][ T63] #2: ffffffff8bd5b5c0 (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) 
| [   29.385140][   T63]
| [   29.385140][   T63] stack backtrace:
[   29.385356][   T63] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   29.385359][   T63] Workqueue: events ipvlan_process_multicast
[   29.385367][   T63] Call Trace:
[   29.385369][   T63]  <TASK>
[ 29.385372][ T63] dump_stack_lvl (lib/dump_stack.c:123) 
[ 29.385380][ T63] lockdep_rcu_suspicious (kernel/locking/lockdep.c:6848) 
[ 29.385393][ T63] 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) 
[ 29.385405][ T63] __dev_queue_xmit (net/core/dev.h:340 net/core/dev.c:4631) 
[ 29.385420][ T63] ? __pfx___dev_queue_xmit (net/core/dev.c:4538) 
[ 29.385424][ T63] ? find_held_lock (kernel/locking/lockdep.c:5341) 
[ 29.385431][ T63] ? __lock_release (kernel/locking/lockdep.c:5527) 
[ 29.385434][ T63] ? ipvlan_process_multicast (./include/linux/rcupdate.h:347 ./include/linux/rcupdate.h:880 drivers/net/ipvlan/ipvlan_core.c:284) 
[ 29.385438][ T63] ? __pfx___lock_release (kernel/locking/lockdep.c:5503) 
[ 29.385442][ T63] ? __pfx_lock_acquire.part.0 (kernel/locking/lockdep.c:5816) 
[ 29.385454][ T63] ? ipvlan_process_multicast (./include/linux/rcupdate.h:347 ./include/linux/rcupdate.h:880 drivers/net/ipvlan/ipvlan_core.c:284) 
[ 29.385462][ T63] ipvlan_process_multicast (./include/linux/netdevice.h:3331 drivers/net/ipvlan/ipvlan_core.c:290) 
[ 29.385478][ T63] ? __pfx_ipvlan_process_multicast (drivers/net/ipvlan/ipvlan_core.c:229) 
[ 29.385484][ T63] ? __pfx___lock_release (kernel/locking/lockdep.c:5503) 
[ 29.385488][ T63] ? __pfx_lock_acquire.part.0 (kernel/locking/lockdep.c:5816) 
[ 29.385493][ T63] ? trace_lock_acquire (./include/trace/events/lock.h:24 (discriminator 21)) 
[ 29.385496][ T63] ? trace_lock_acquire (./include/trace/events/lock.h:24 (discriminator 21)) 
[ 29.385503][ T63] ? lock_acquire (kernel/locking/lockdep.c:5824) 
[ 29.385511][ T63] ? process_one_work (kernel/workqueue.c:3238) 
[ 29.385514][ T63] ? process_one_work (kernel/workqueue.c:3214) 
[ 29.385517][ T63] process_one_work (kernel/workqueue.c:3238) 
[ 29.385530][ T63] ? __pfx___lock_release (kernel/locking/lockdep.c:5503) 
[ 29.385535][ T63] ? __pfx_process_one_work (kernel/workqueue.c:3140) 
[ 29.385548][ T63] ? assign_work (kernel/workqueue.c:1200) 
[ 29.385557][ T63] worker_thread (kernel/workqueue.c:3313 kernel/workqueue.c:3400) 
[ 29.385562][ T63] ? lockdep_hardirqs_on_prepare (kernel/locking/lockdep.c:4349 kernel/locking/lockdep.c:4408) 
[ 29.385573][ T63] ? __pfx_worker_thread (kernel/workqueue.c:3346) 
[ 29.385580][ T63] kthread (kernel/kthread.c:464) 
[ 29.385586][ T63] ? __pfx_kthread (kernel/kthread.c:413) 
[ 29.385596][ T63] ? __pfx_kthread (kernel/kthread.c:413) 
[ 29.385602][ T63] ret_from_fork (arch/x86/kernel/process.c:148) 
[ 29.385607][ T63] ? __pfx_kthread (kernel/kthread.c:413) 


Finger prints:
lockdep_rcu_suspicious:dev_hard_start_xmit:__dev_queue_xmit:ipvlan_process_multicast:process_one_work