INFO: rcu_sched self-detected stall on CPU 0-....: (124999 ticks this GP) idle=6ea/1/4611686018427387906 softirq=9748/9748 fqs=31240 (t=125000 jiffies g=4823 c=4822 q=10) NMI backtrace for cpu 0 CPU: 0 PID: 4469 Comm: syzkaller058368 Not tainted 4.16.0-rc7+ #5 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x194/0x24d lib/dump_stack.c:53 nmi_cpu_backtrace+0x1d2/0x210 lib/nmi_backtrace.c:103 nmi_trigger_cpumask_backtrace+0x123/0x180 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+0x186/0x1de kernel/rcu/tree.c:1375 print_cpu_stall kernel/rcu/tree.c:1524 [inline] check_cpu_stall.isra.61+0xbb8/0x15b0 kernel/rcu/tree.c:1592 __rcu_pending kernel/rcu/tree.c:3361 [inline] rcu_pending kernel/rcu/tree.c:3423 [inline] rcu_check_callbacks+0x238/0xd20 kernel/rcu/tree.c:2763 update_process_times+0x30/0x60 kernel/time/timer.c:1636 tick_sched_handle+0x85/0x160 kernel/time/tick-sched.c:162 tick_sched_timer+0x42/0x120 kernel/time/tick-sched.c:1194 __run_hrtimer kernel/time/hrtimer.c:1349 [inline] __hrtimer_run_queues+0x39c/0xec0 kernel/time/hrtimer.c:1411 hrtimer_interrupt+0x2a5/0x6f0 kernel/time/hrtimer.c:1469 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1025 [inline] smp_apic_timer_interrupt+0x14a/0x700 arch/x86/kernel/apic/apic.c:1050 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:857 RIP: 0010:echo_buf drivers/tty/n_tty.c:144 [inline] RIP: 0010:__process_echoes+0x5d9/0x770 drivers/tty/n_tty.c:732 RSP: 0018:ffff8801af12f7f0 EFLAGS: 00000202 ORIG_RAX: ffffffffffffff12 RAX: 0000000000000594 RBX: ffffc90001946000 RCX: ffffffff82f38469 RDX: 0000000000000000 RSI: 1ffff1003543c565 RDI: ffffc900019477f4 RBP: ffff8801af12f858 R08: 1ffff10035e25ea4 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 00000005e6b39594 R13: dffffc0000000000 R14: 00000005e6b39594 R15: 0000000000003803 flush_echoes drivers/tty/n_tty.c:799 [inline] __receive_buf drivers/tty/n_tty.c:1615 [inline] n_tty_receive_buf_common+0x1380/0x2520 drivers/tty/n_tty.c:1709 n_tty_receive_buf+0x30/0x40 drivers/tty/n_tty.c:1738 tiocsti drivers/tty/tty_io.c:2171 [inline] tty_ioctl+0x9c5/0x1610 drivers/tty/tty_io.c:2557 vfs_ioctl fs/ioctl.c:46 [inline] do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:686 SYSC_ioctl fs/ioctl.c:701 [inline] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692 do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x446979 RSP: 002b:00007fb18094bd18 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00000000006e29fc RCX: 0000000000446979 RDX: 00000000200000c0 RSI: 0000000000005412 RDI: 0000000000000004 RBP: 00000000006e29f8 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 6d74702f7665642f R13: 00007ffc95813d0f R14: 00007fb18094c9c0 R15: 0000000000000001