INIT: Entering runlevel: 2 [info] Using makefile-style concurrent boot in runlevel 2. [....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 Warning: Permanently added '10.128.10.4' (ECDSA) to the list of known hosts. executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program syzkaller login: [ 447.539028] INFO: rcu_sched self-detected stall on CPU [ 447.544590] 0-....: (124999 ticks this GP) idle=6aa/1/4611686018427387906 softirq=9528/9528 fqs=31245 [ 447.554151] (t=125000 jiffies g=4714 c=4713 q=8) [ 447.559056] NMI backtrace for cpu 0 [ 447.562655] CPU: 0 PID: 51 Comm: kworker/u4:2 Not tainted 4.16.0-rc7+ #3 [ 447.569460] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 447.578898] Workqueue: events_unbound flush_to_ldisc [ 447.584004] Call Trace: [ 447.586566] [ 447.588743] dump_stack+0x194/0x24d [ 447.592349] ? arch_local_irq_restore+0x53/0x53 [ 447.597041] ? lock_release+0xa40/0xa40 [ 447.600990] ? nmi_cpu_backtrace+0x1be/0x210 [ 447.605408] ? lapic_can_unplug_cpu+0xa0/0xa0 [ 447.609875] nmi_cpu_backtrace+0x1d2/0x210 [ 447.614083] ? lapic_can_unplug_cpu+0xa0/0xa0 [ 447.618548] nmi_trigger_cpumask_backtrace+0x123/0x180 [ 447.623799] arch_trigger_cpumask_backtrace+0x14/0x20 [ 447.628990] rcu_dump_cpu_stacks+0x186/0x1de [ 447.633399] check_cpu_stall.isra.61+0xbb8/0x15b0 [ 447.638223] ? rcu_lockdep_current_cpu_online+0x190/0x190 [ 447.643730] ? debug_check_no_locks_freed+0x3c0/0x3c0 [ 447.648894] ? __lock_acquire+0x664/0x3e00 [ 447.653145] ? find_held_lock+0x35/0x1d0 [ 447.657202] ? notifier_call_chain+0x136/0x2c0 [ 447.661760] ? lock_downgrade+0x980/0x980 [ 447.665881] ? trace_hardirqs_off+0x10/0x10 [ 447.670171] ? lock_release+0xa40/0xa40 [ 447.674131] ? trace_hardirqs_off+0x10/0x10 [ 447.678423] ? find_held_lock+0x35/0x1d0 [ 447.682459] ? trace_hardirqs_off+0x10/0x10 [ 447.686752] ? cpuacct_account_field+0x1e4/0x3b0 [ 447.691482] ? find_held_lock+0x35/0x1d0 [ 447.695515] ? trace_hardirqs_off+0x10/0x10 [ 447.699810] ? __lock_is_held+0xb6/0x140 [ 447.703865] rcu_check_callbacks+0x238/0xd20 [ 447.708248] ? rcu_cpu_stall_reset+0x260/0x260 [ 447.712805] ? trace_hardirqs_off+0xd/0x10 [ 447.717026] ? raise_softirq+0x325/0x490 [ 447.721066] ? raise_softirq_irqoff+0x320/0x320 [ 447.725732] ? read_boot_clock64+0x70/0x70 [ 447.729939] ? lock_downgrade+0x980/0x980 [ 447.734057] ? hrtimer_run_queues+0x5e/0x380 [ 447.738441] ? run_local_timers+0x14c/0x1b0 [ 447.742733] ? timer_clear_idle+0x50/0x50 [ 447.746887] ? account_process_tick+0xd4/0x3e0 [ 447.751442] ? thread_group_cputime+0xef0/0xef0 [ 447.756083] ? get_monotonic_coarse64+0x470/0x470 [ 447.760904] update_process_times+0x30/0x60 [ 447.765227] tick_sched_handle+0x85/0x160 [ 447.769358] tick_sched_timer+0x42/0x120 [ 447.773392] __hrtimer_run_queues+0x39c/0xec0 [ 447.777863] ? tick_sched_do_timer+0xe0/0xe0 [ 447.782248] ? hrtimer_fixup_init+0x70/0x70 [ 447.786574] ? pvclock_read_flags+0x160/0x160 [ 447.791050] ? lock_acquire+0x1d5/0x580 [ 447.794997] ? ktime_get+0x26f/0x3a0 [ 447.798689] ? kvm_clock_get_cycles+0x25/0x30 [ 447.803156] ? ktime_get_update_offsets_now+0x34a/0x520 [ 447.808495] ? do_timer+0x50/0x50 [ 447.811930] ? native_apic_msr_write+0x5c/0x80 [ 447.816484] ? rcu_idle_enter+0x530/0x530 [ 447.820601] ? lapic_next_event+0x54/0x80 [ 447.824720] ? clockevents_program_event+0x108/0x2e0 [ 447.829799] hrtimer_interrupt+0x2a5/0x6f0 [ 447.834082] smp_apic_timer_interrupt+0x14a/0x700 [ 447.838901] ? smp_call_function_single_interrupt+0x640/0x640 [ 447.844756] ? _raw_spin_lock+0x32/0x40 [ 447.848705] ? _raw_spin_unlock+0x22/0x30 [ 447.853174] ? handle_edge_irq+0x2b4/0x7c0 [ 447.857401] ? task_prio+0x50/0x50 [ 447.860979] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 447.865804] apic_timer_interrupt+0xf/0x20 [ 447.870010] [ 447.872268] RIP: 0010:__sanitizer_cov_trace_pc+0x4b/0x50 [ 447.877691] RSP: 0018:ffff8801d96170a8 EFLAGS: 00000293 ORIG_RAX: ffffffffffffff12 [ 447.885373] RAX: ffff8801d960a5c0 RBX: ffffc90001fb8000 RCX: ffffffff82f38349 [ 447.892613] RDX: 0000000000000000 RSI: 1ffff1003b2c15e4 RDI: ffffc90001fb9963 [ 447.899854] RBP: ffff8801d96170a8 R08: 1ffff1003b2c2dbd R09: 0000000000000000 [ 447.907095] R10: 0000000000000000 R11: 0000000000000000 R12: 000000057efa5704 [ 447.914335] R13: dffffc0000000000 R14: 000000057efa5704 R15: 0000000000003321 [ 447.921605] ? __process_echoes+0x5c9/0x770 [ 447.925905] __process_echoes+0x5c9/0x770 [ 447.930039] n_tty_receive_buf_common+0x1380/0x2520 [ 447.935105] ? kfree+0x90/0x260 [ 447.938375] ? n_tty_receive_char_special+0x2c90/0x2c90 [ 447.943712] ? lock_release+0xa40/0xa40 [ 447.947704] ? free_obj_work+0x690/0x690 [ 447.951737] ? __mutex_unlock_slowpath+0xe9/0xac0 [ 447.956563] n_tty_receive_buf2+0x33/0x40 [ 447.960685] ? n_tty_receive_buf_common+0x2520/0x2520 [ 447.965846] tty_ldisc_receive_buf+0xa7/0x180 [ 447.970316] tty_port_default_receive_buf+0x106/0x160 [ 447.975479] ? tty_port_lower_dtr_rts+0x80/0x80 [ 447.980120] ? trace_hardirqs_on+0xd/0x10 [ 447.984246] flush_to_ldisc+0x3c4/0x590 [ 447.988201] ? tty_buffer_free+0x100/0x100 [ 447.992419] ? __lock_is_held+0xb6/0x140 [ 447.996509] process_one_work+0xc47/0x1bb0 [ 448.000714] ? debug_check_no_locks_freed+0x3c0/0x3c0 [ 448.005871] ? trace_hardirqs_on+0xd/0x10 [ 448.009999] ? pwq_dec_nr_in_flight+0x450/0x450 [ 448.014661] ? __schedule+0x903/0x1ec0 [ 448.018530] ? retint_kernel+0x10/0x10 [ 448.022393] ? trace_hardirqs_off+0x10/0x10 [ 448.026687] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 448.031441] ? lock_acquire+0x1d5/0x580 [ 448.035397] ? lock_acquire+0x1d5/0x580 [ 448.039343] ? worker_thread+0x4a3/0x1990 [ 448.043461] ? lock_downgrade+0x980/0x980 [ 448.047582] ? lock_release+0xa40/0xa40 [ 448.051527] ? retint_kernel+0x10/0x10 [ 448.055388] ? do_raw_spin_trylock+0x190/0x190 [ 448.059952] worker_thread+0x223/0x1990 [ 448.063914] ? process_one_work+0x1bb0/0x1bb0 [ 448.068421] ? put_task_stack+0x116/0x270 [ 448.072545] ? finish_task_switch+0x539/0x7e0 [ 448.077021] ? copy_overflow+0x20/0x20 [ 448.080897] ? __schedule+0x903/0x1ec0 [ 448.084767] ? trace_hardirqs_off+0x10/0x10 [ 448.089066] ? find_held_lock+0x35/0x1d0 [ 448.093106] ? find_held_lock+0x35/0x1d0 [ 448.097144] ? complete+0x62/0x80 [ 448.100576] ? __schedule+0x1ec0/0x1ec0 [ 448.104518] ? do_wait_intr_irq+0x3e0/0x3e0 [ 448.108810] ? __lockdep_init_map+0xe4/0x650 [ 448.113191] ? do_raw_spin_trylock+0x190/0x190 [ 448.117744] ? lockdep_init_map+0x9/0x10 [ 448.121776] ? _raw_spin_unlock_irqrestore+0x31/0xc0 [ 448.126850] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 448.131837] ? trace_hardirqs_on+0xd/0x10 [ 448.135956] ? __kthread_parkme+0x176/0x240 [ 448.140253] kthread+0x33c/0x400 [ 448.143591] ? process_one_work+0x1bb0/0x1bb0 [ 448.148057] ? kthread_stop+0x7a0/0x7a0 [ 448.152009] ret_from_fork+0x3a/0x50