INFO: rcu_sched self-detected stall on CPU 1-...!: (124999 ticks this GP) idle=2a6/1/4611686018427387906 softirq=45868/45868 fqs=19 (t=125000 jiffies g=26063 c=26062 q=290) rcu_sched kthread starved for 124918 jiffies! g26063 c26062 f0x0 RCU_GP_WAIT_FQS(3) ->state=0x0 ->cpu=1 RCU grace-period kthread stack dump: rcu_sched R running task 23768 9 2 0x80000000 Call Trace: context_switch kernel/sched/core.c:2848 [inline] __schedule+0x801/0x1e30 kernel/sched/core.c:3490 schedule+0xef/0x430 kernel/sched/core.c:3549 schedule_timeout+0x138/0x240 kernel/time/timer.c:1801 rcu_gp_kthread+0x6b5/0x1940 kernel/rcu/tree.c:2231 kthread+0x345/0x410 kernel/kthread.c:238 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:412 NMI backtrace for cpu 1 CPU: 1 PID: 78 Comm: kworker/u4:3 Not tainted 4.17.0-rc4+ #43 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: events_unbound flush_to_ldisc Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1b9/0x294 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:1376 print_cpu_stall kernel/rcu/tree.c:1525 [inline] check_cpu_stall.isra.61.cold.80+0x36c/0x59a kernel/rcu/tree.c:1593 __rcu_pending kernel/rcu/tree.c:3356 [inline] rcu_pending kernel/rcu/tree.c:3401 [inline] rcu_check_callbacks+0x21b/0xad0 kernel/rcu/tree.c:2763 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+0x3e3/0x10a0 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+0x15d/0x710 arch/x86/kernel/apic/apic.c:1050 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:863 RIP: 0010:add_echo_byte drivers/tty/n_tty.c:813 [inline] RIP: 0010:echo_char_raw drivers/tty/n_tty.c:891 [inline] RIP: 0010:eraser drivers/tty/n_tty.c:1053 [inline] RIP: 0010:n_tty_receive_char_special+0x1934/0x31c0 drivers/tty/n_tty.c:1283 RSP: 0018:ffff8801d974f220 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13 RAX: 1ffff92000c18bcb RBX: 0000000231d57bf9 RCX: dffffc0000000000 RDX: 0000000000000000 RSI: dffffc0000000000 RDI: ffffc900060c5e58 RBP: ffff8801d974f310 R08: ffff8801d95cc4c0 R09: 0000000000000006 R10: ffff8801d95cc4c0 R11: 0000000000000000 R12: 0000000000000bf8 R13: ffffc900060c4000 R14: 0000000000000bf7 R15: ffffffffc7c1dc93 n_tty_receive_buf_fast drivers/tty/n_tty.c:1577 [inline] __receive_buf drivers/tty/n_tty.c:1611 [inline] n_tty_receive_buf_common+0x20ca/0x2c50 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+0x110/0x170 drivers/tty/tty_port.c:38 receive_buf drivers/tty/tty_buffer.c:475 [inline] flush_to_ldisc+0x3e9/0x560 drivers/tty/tty_buffer.c:524 process_one_work+0xc1e/0x1b50 kernel/workqueue.c:2145 worker_thread+0x1cc/0x1440 kernel/workqueue.c:2279 kthread+0x345/0x410 kernel/kthread.c:238 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:412