======================================
| [ 31.607793][ T56] #1: ffffc900003cfd40 ((work_completion)(&port->wq)){+.+.}-{0:0}, at: process_one_work (kernel/workqueue.c:3214) 
| [ 31.608096][ T56] #2: ffffffffafd5b5c0 (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) 
| [   31.608382][   T56]
| [   31.608382][   T56] stack backtrace:
[   31.608565][   T56] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   31.608567][   T56] Workqueue: events ipvlan_process_multicast
[   31.608574][   T56] Call Trace:
[   31.608576][   T56]  <TASK>
[ 31.608581][ T56] dump_stack_lvl (lib/dump_stack.c:123) 
[ 31.608587][ T56] lockdep_rcu_suspicious (kernel/locking/lockdep.c:6848) 
[ 31.608598][ T56] 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) 
[ 31.608610][ T56] __dev_queue_xmit (net/core/dev.h:340 net/core/dev.c:4631) 
[ 31.608626][ T56] ? __pfx___dev_queue_xmit (net/core/dev.c:4538) 
[ 31.608629][ T56] ? find_held_lock (kernel/locking/lockdep.c:5341) 
[ 31.608637][ T56] ? __lock_release (kernel/locking/lockdep.c:5527) 
[ 31.608639][ T56] ? ipvlan_process_multicast (./include/linux/rcupdate.h:347 ./include/linux/rcupdate.h:880 drivers/net/ipvlan/ipvlan_core.c:284) 
[ 31.608644][ T56] ? __pfx___lock_release (kernel/locking/lockdep.c:5503) 
[ 31.608648][ T56] ? __pfx_lock_acquire.part.0 (kernel/locking/lockdep.c:5816) 
[ 31.608660][ T56] ? ipvlan_process_multicast (./include/linux/rcupdate.h:347 ./include/linux/rcupdate.h:880 drivers/net/ipvlan/ipvlan_core.c:284) 
[ 31.608668][ T56] ipvlan_process_multicast (./include/linux/netdevice.h:3331 drivers/net/ipvlan/ipvlan_core.c:290) 
[ 31.608685][ T56] ? __pfx_ipvlan_process_multicast (drivers/net/ipvlan/ipvlan_core.c:229) 
[ 31.608690][ T56] ? __pfx___lock_release (kernel/locking/lockdep.c:5503) 
[ 31.608694][ T56] ? __pfx_lock_acquire.part.0 (kernel/locking/lockdep.c:5816) 
[ 31.608699][ T56] ? trace_lock_acquire (./include/trace/events/lock.h:24 (discriminator 21)) 
[ 31.608702][ T56] ? trace_lock_acquire (./include/trace/events/lock.h:24 (discriminator 21)) 
[ 31.608709][ T56] ? lock_acquire (kernel/locking/lockdep.c:5824) 
[ 31.608718][ T56] ? process_one_work (kernel/workqueue.c:3238) 
[ 31.608721][ T56] ? process_one_work (kernel/workqueue.c:3214) 
[ 31.608724][ T56] process_one_work (kernel/workqueue.c:3238) 
[ 31.608737][ T56] ? __pfx___lock_release (kernel/locking/lockdep.c:5503) 
[ 31.608741][ T56] ? __pfx_process_one_work (kernel/workqueue.c:3140) 
[ 31.608755][ T56] ? assign_work (kernel/workqueue.c:1200) 
[ 31.608764][ T56] worker_thread (kernel/workqueue.c:3313 kernel/workqueue.c:3400) 
[ 31.608769][ T56] ? lockdep_hardirqs_on_prepare (kernel/locking/lockdep.c:4349 kernel/locking/lockdep.c:4408) 
[ 31.608780][ T56] ? __pfx_worker_thread (kernel/workqueue.c:3346) 
[ 31.608786][ T56] kthread (kernel/kthread.c:464) 
[ 31.608792][ T56] ? __pfx_kthread (kernel/kthread.c:413) 
[ 31.608801][ T56] ? __pfx_kthread (kernel/kthread.c:413) 
[ 31.608807][ T56] ret_from_fork (arch/x86/kernel/process.c:148) 
[ 31.608811][ T56] ? __pfx_kthread (kernel/kthread.c:413) 


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