rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P1321
rcu: 	(detected by 1, t=10502 jiffies, g=157997, q=6970 ncpus=2)
task:aoe_tx0         state:R  running task     stack:25864 pid:1321  tgid:1321  ppid:2      task_flags:0x208040 flags:0x00080000
Call Trace:
 <IRQ>
 sched_show_task+0x49d/0x630 kernel/sched/core.c:7901
 rcu_print_detail_task_stall_rnp kernel/rcu/tree_stall.h:292 [inline]
 print_other_cpu_stall+0xf78/0x1340 kernel/rcu/tree_stall.h:681
 check_cpu_stall kernel/rcu/tree_stall.h:857 [inline]
 rcu_pending kernel/rcu/tree.c:3671 [inline]
 rcu_sched_clock_irq+0xa47/0x11b0 kernel/rcu/tree.c:2706
 update_process_times+0x235/0x2d0 kernel/time/timer.c:2473
 tick_sched_handle kernel/time/tick-sched.c:276 [inline]
 tick_nohz_handler+0x39a/0x520 kernel/time/tick-sched.c:297
 __run_hrtimer kernel/time/hrtimer.c:1777 [inline]
 __hrtimer_run_queues+0x506/0xd40 kernel/time/hrtimer.c:1841
 hrtimer_interrupt+0x45d/0xa90 kernel/time/hrtimer.c:1903
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1041 [inline]
 __sysvec_apic_timer_interrupt+0x10b/0x410 arch/x86/kernel/apic/apic.c:1058
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1052 [inline]
 sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1052
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:lock_is_held_type+0x137/0x190 kernel/locking/lockdep.c:5945
Code: 01 75 44 48 c7 04 24 00 00 00 00 9c 8f 04 24 f7 04 24 00 02 00 00 75 4c 41 f7 c4 00 02 00 00 74 01 fb 65 48 8b 05 f9 39 ff 06 <48> 3b 44 24 08 75 43 89 d8 48 83 c4 10 5b 41 5c 41 5d 41 5e 41 5f
RSP: 0018:ffffc9000530f4b8 EFLAGS: 00000206
RAX: 681f44cc5a802000 RBX: 0000000000000000 RCX: 681f44cc5a802000
RDX: 0000000000000200 RSI: ffffffff8d03d5c8 RDI: ffffffff8b3f4d60
RBP: 00000000ffffffff R08: 0000000000000000 R09: ffffffff850918b1
R10: dffffc0000000000 R11: ffffed1028666251 R12: 0000000000000246
R13: ffff8880270ebc00 R14: ffffffff8d7aa580 R15: 0000000000000006
 lock_is_held include/linux/lockdep.h:249 [inline]
 __might_resched+0xa6/0x5d0 kernel/sched/core.c:8887
 __rt_spin_lock kernel/locking/spinlock_rt.c:48 [inline]
 rt_spin_lock+0xc7/0x3e0 kernel/locking/spinlock_rt.c:57
 spin_lock include/linux/spinlock_rt.h:44 [inline]
 uart_port_lock_irqsave include/linux/serial_core.h:717 [inline]
 uart_port_ref_lock+0xe1/0x3b0 drivers/tty/serial/serial_core.c:83
 uart_write+0x72/0x120 drivers/tty/serial/serial_core.c:624
 handle_tx+0x23f/0x610 drivers/net/caif/caif_serial.c:222
 __netdev_start_xmit include/linux/netdevice.h:5248 [inline]
 netdev_start_xmit include/linux/netdevice.h:5257 [inline]
 xmit_one net/core/dev.c:3845 [inline]
 dev_hard_start_xmit+0x2f0/0x870 net/core/dev.c:3861
 __dev_queue_xmit+0x1b50/0x3b70 net/core/dev.c:4763
 dev_queue_xmit include/linux/netdevice.h:3365 [inline]
 tx+0x6b/0x190 drivers/block/aoe/aoenet.c:62
 kthread+0x1d0/0x3e0 drivers/block/aoe/aoecmd.c:1241
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>