======================================
| [ 32.010230][ T51] #1: ffffc9000037fd40 ((work_completion)(&port->wq)){+.+.}-{0:0}, at: process_one_work (kernel/workqueue.c:3214) 
| [ 32.010606][ T51] #2: ffffffff9415b5c0 (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) 
| [   32.010891][   T51]
| [   32.010891][   T51] stack backtrace:
[   32.011098][   T51] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   32.011101][   T51] Workqueue: events ipvlan_process_multicast
[   32.011110][   T51] Call Trace:
[   32.011112][   T51]  <TASK>
[ 32.011116][ T51] dump_stack_lvl (lib/dump_stack.c:123) 
[ 32.011124][ T51] lockdep_rcu_suspicious (kernel/locking/lockdep.c:6848) 
[ 32.011137][ T51] 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) 
[ 32.011149][ T51] __dev_queue_xmit (net/core/dev.h:340 net/core/dev.c:4631) 
[ 32.011165][ T51] ? __pfx___dev_queue_xmit (net/core/dev.c:4538) 
[ 32.011168][ T51] ? find_held_lock (kernel/locking/lockdep.c:5341) 
[ 32.011176][ T51] ? __lock_release (kernel/locking/lockdep.c:5527) 
[ 32.011178][ T51] ? ipvlan_process_multicast (./include/linux/rcupdate.h:347 ./include/linux/rcupdate.h:880 drivers/net/ipvlan/ipvlan_core.c:284) 
[ 32.011183][ T51] ? __pfx___lock_release (kernel/locking/lockdep.c:5503) 
[ 32.011186][ T51] ? __pfx_lock_acquire.part.0 (kernel/locking/lockdep.c:5816) 
[ 32.011199][ T51] ? ipvlan_process_multicast (./include/linux/rcupdate.h:347 ./include/linux/rcupdate.h:880 drivers/net/ipvlan/ipvlan_core.c:284) 
[ 32.011207][ T51] ipvlan_process_multicast (./include/linux/netdevice.h:3331 drivers/net/ipvlan/ipvlan_core.c:290) 
[ 32.011223][ T51] ? __pfx_ipvlan_process_multicast (drivers/net/ipvlan/ipvlan_core.c:229) 
[ 32.011229][ T51] ? __pfx___lock_release (kernel/locking/lockdep.c:5503) 
[ 32.011233][ T51] ? __pfx_lock_acquire.part.0 (kernel/locking/lockdep.c:5816) 
[ 32.011238][ T51] ? trace_lock_acquire (./include/trace/events/lock.h:24 (discriminator 21)) 
[ 32.011241][ T51] ? trace_lock_acquire (./include/trace/events/lock.h:24 (discriminator 21)) 
[ 32.011248][ T51] ? lock_acquire (kernel/locking/lockdep.c:5824) 
[ 32.011256][ T51] ? process_one_work (kernel/workqueue.c:3238) 
[ 32.011259][ T51] ? process_one_work (kernel/workqueue.c:3214) 
[ 32.011262][ T51] process_one_work (kernel/workqueue.c:3238) 
[ 32.011275][ T51] ? __pfx___lock_release (kernel/locking/lockdep.c:5503) 
[ 32.011280][ T51] ? __pfx_process_one_work (kernel/workqueue.c:3140) 
[ 32.011296][ T51] ? assign_work (kernel/workqueue.c:1200) 
[ 32.011305][ T51] worker_thread (kernel/workqueue.c:3313 kernel/workqueue.c:3400) 
[ 32.011310][ T51] ? lockdep_hardirqs_on_prepare (kernel/locking/lockdep.c:4349 kernel/locking/lockdep.c:4408) 
[ 32.011321][ T51] ? __pfx_worker_thread (kernel/workqueue.c:3346) 
[ 32.011328][ T51] kthread (kernel/kthread.c:464) 
[ 32.011334][ T51] ? __pfx_kthread (kernel/kthread.c:413) 
[ 32.011343][ T51] ? __pfx_kthread (kernel/kthread.c:413) 
[ 32.011349][ T51] ret_from_fork (arch/x86/kernel/process.c:148) 
[ 32.011354][ T51] ? __pfx_kthread (kernel/kthread.c:413) 


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