INFO: rcu_sched self-detected stall on CPU
	0-....: (124999 ticks this GP) idle=b72/1/4611686018427387906 softirq=91593/91593 fqs=31232 
	 (t=125000 jiffies g=51650 c=51649 q=482)
NMI backtrace for cpu 0
CPU: 0 PID: 6716 Comm: kworker/u4:5 Not tainted 4.18.0-rc1+ #107
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events_unbound flush_to_ldisc
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1c9/0x2b4 lib/dump_stack.c:113
 nmi_cpu_backtrace.cold.4+0x19/0xce lib/nmi_backtrace.c:103
 nmi_trigger_cpumask_backtrace+0x151/0x192 lib/nmi_backtrace.c:62
 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38
 trigger_single_cpu_backtrace include/linux/nmi.h:156 [inline]
 rcu_dump_cpu_stacks+0x175/0x1c2 kernel/rcu/tree.c:1336
 print_cpu_stall kernel/rcu/tree.c:1485 [inline]
 check_cpu_stall.isra.60.cold.78+0x36c/0x5a6 kernel/rcu/tree.c:1553
 __rcu_pending kernel/rcu/tree.c:3244 [inline]
 rcu_pending kernel/rcu/tree.c:3291 [inline]
 rcu_check_callbacks+0x23f/0xcd0 kernel/rcu/tree.c:2646
 update_process_times+0x2d/0x70 kernel/time/timer.c:1636
 tick_sched_handle+0x9f/0x180 kernel/time/tick-sched.c:164
 tick_sched_timer+0x45/0x130 kernel/time/tick-sched.c:1274
 __run_hrtimer kernel/time/hrtimer.c:1398 [inline]
 __hrtimer_run_queues+0x3eb/0x10c0 kernel/time/hrtimer.c:1460
 hrtimer_interrupt+0x2f3/0x750 kernel/time/hrtimer.c:1518
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1025 [inline]
 smp_apic_timer_interrupt+0x165/0x730 arch/x86/kernel/apic/apic.c:1050
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:863
 </IRQ>
RIP: 0010:__process_echoes+0x249/0x8d0 drivers/tty/n_tty.c:733
Code: 03 83 e2 07 0f b6 04 08 38 d0 7f 08 84 c0 0f 85 02 06 00 00 47 0f b6 b4 34 60 12 00 00 bf 82 ff ff ff 44 89 f6 e8 f7 9e d7 fd <41> 80 fe 82 0f 84 4f 05 00 00 e8 18 9e d7 fd 4c 8d 73 02 4c 89 f3 
RSP: 0018:ffff8801b0b5f248 EFLAGS: 00000293 ORIG_RAX: ffffffffffffff13
RAX: 0000000000000000 RBX: 00000002c2f94bbe RCX: ffffffff83a40c79
RDX: 0000000000000000 RSI: 0000000000000082 RDI: 0000000000000001
RBP: ffff8801b0b5f2b0 R08: ffff8801af984740 R09: 0000000000000006
R10: ffff8801af984740 R11: 0000000000000000 R12: ffffc90001aae000
R13: 0000000000001656 R14: 0000000000000000 R15: 00000000000000ff
 commit_echoes+0x163/0x1d0 drivers/tty/n_tty.c:764
 n_tty_receive_char_inline drivers/tty/n_tty.c:1388 [inline]
 n_tty_receive_buf_standard drivers/tty/n_tty.c:1550 [inline]
 __receive_buf drivers/tty/n_tty.c:1613 [inline]
 n_tty_receive_buf_common+0x9d4/0x2c60 drivers/tty/n_tty.c:1709
 n_tty_receive_buf2+0x33/0x40 drivers/tty/n_tty.c:1744
 tty_ldisc_receive_buf+0xb0/0x190 drivers/tty/tty_buffer.c:456
 tty_port_default_receive_buf+0x115/0x180 drivers/tty/tty_port.c:38
 receive_buf drivers/tty/tty_buffer.c:475 [inline]
 flush_to_ldisc+0x3fd/0x570 drivers/tty/tty_buffer.c:524
 process_one_work+0xc73/0x1ba0 kernel/workqueue.c:2153
 worker_thread+0x189/0x13c0 kernel/workqueue.c:2296
 kthread+0x345/0x410 kernel/kthread.c:240
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:412