[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [ 38.188321] audit: type=1800 audit(1549453352.717:25): pid=7667 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="cron" dev="sda1" ino=2414 res=0 [ 38.223198] audit: type=1800 audit(1549453352.717:26): pid=7667 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="mcstrans" dev="sda1" ino=2457 res=0 [ 38.256964] audit: type=1800 audit(1549453352.717:27): pid=7667 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="restorecond" dev="sda1" ino=2436 res=0 [....] 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 '10.128.0.76' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 587.477707] INFO: task syz-executor340:7818 blocked for more than 140 seconds. [ 587.485538] Not tainted 5.0.0-rc5 #60 [ 587.490585] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 587.498621] syz-executor340 D28128 7818 7816 0x80000000 [ 587.504248] Call Trace: [ 587.506827] __schedule+0x817/0x1cc0 [ 587.510586] ? trace_hardirqs_off+0x62/0x220 [ 587.514989] ? pci_mmcfg_check_reserved+0x170/0x170 [ 587.520045] ? mark_held_locks+0x100/0x100 [ 587.524268] schedule+0x92/0x180 [ 587.527659] schedule_timeout+0x8ca/0xfd0 [ 587.531795] ? wait_for_completion+0x294/0x440 [ 587.536362] ? find_held_lock+0x35/0x130 [ 587.540452] ? usleep_range+0x170/0x170 [ 587.544427] ? kasan_check_read+0x11/0x20 [ 587.548613] ? _raw_spin_unlock_irq+0x28/0x90 [ 587.553092] ? wait_for_completion+0x294/0x440 [ 587.557822] ? _raw_spin_unlock_irq+0x28/0x90 [ 587.562311] ? lockdep_hardirqs_on+0x415/0x5d0 [ 587.566874] ? trace_hardirqs_on+0x67/0x230 [ 587.571219] ? kasan_check_read+0x11/0x20 [ 587.575362] wait_for_completion+0x29c/0x440 [ 587.579802] ? lockdep_hardirqs_on+0x415/0x5d0 [ 587.584374] ? wait_for_completion_interruptible+0x4b0/0x4b0 [ 587.590271] ? wake_up_q+0x100/0x100 [ 587.593985] ? percpu_ref_kill_and_confirm+0x1b7/0x3b0 [ 587.599370] exit_aio+0x321/0x3a0 [ 587.602827] ? io_submit_one+0x1cf0/0x1cf0 [ 587.607059] ? mutex_unlock+0xd/0x10 [ 587.610932] mmput+0xcf/0x4c0 [ 587.614032] do_exit+0x838/0x2fd0 [ 587.617473] ? lock_downgrade+0x810/0x810 [ 587.621745] ? kasan_check_read+0x11/0x20 [ 587.625907] ? mm_update_next_owner+0x660/0x660 [ 587.630611] ? __x64_sys_io_submit+0x37d/0x580 [ 587.635268] ? __ia32_sys_io_destroy+0x420/0x420 [ 587.640064] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 587.644920] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 587.649753] do_group_exit+0x135/0x370 [ 587.653663] __x64_sys_exit_group+0x44/0x50 [ 587.658027] do_syscall_64+0x103/0x610 [ 587.661964] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 587.667208] RIP: 0033:0x43ed88 [ 587.670458] Code: c1 f9 1f 45 88 11 49 83 c1 01 41 29 d0 f7 eb c1 fa 02 29 ca 89 d1 75 ca 41 8d 43 01 49 63 cb 4c 63 c0 0f b6 57 09 80 fa 5a 0f <84> 26 01 00 00 88 14 0e 44 0f b6 4f 08 ba 67 00 00 00 44 89 c8 41 [ 587.689390] RSP: 002b:00007ffec60f9c08 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 587.697086] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ed88 [ 587.704384] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 587.711702] RBP: 00000000004be688 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 587.719009] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 [ 587.726270] R13: 00000000006d0180 R14: 0000000000000000 R15: 0000000000000000 [ 587.733593] [ 587.733593] Showing all locks held in the system: [ 587.739949] 1 lock held by khungtaskd/1039: [ 587.744249] #0: 000000001d6b9666 (rcu_read_lock){....}, at: debug_show_all_locks+0x5f/0x27e [ 587.753045] 1 lock held by rsyslogd/7705: [ 587.757192] #0: 00000000450753bf (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xee/0x110 [ 587.765127] 2 locks held by getty/7796: [ 587.769109] #0: 000000007bfbd110 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 [ 587.777459] #1: 00000000daa4e33f (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b70 [ 587.786484] 2 locks held by getty/7797: [ 587.790514] #0: 00000000b66dc3be (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 [ 587.798799] #1: 000000002457192c (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b70 [ 587.807680] 2 locks held by getty/7798: [ 587.811640] #0: 00000000a11f714e (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 [ 587.819962] #1: 000000009f6cadd6 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b70 [ 587.828833] 2 locks held by getty/7799: [ 587.832790] #0: 000000002eb1b905 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 [ 587.841048] #1: 00000000c211b15f (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b70 [ 587.849917] 2 locks held by getty/7800: [ 587.853866] #0: 00000000ae0c5e97 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 [ 587.862244] #1: 0000000060ea4ae5 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b70 [ 587.871137] 2 locks held by getty/7801: [ 587.875097] #0: 00000000f7e9ba1b (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 [ 587.883487] #1: 000000000ff4eb43 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b70 [ 587.892364] 2 locks held by getty/7802: [ 587.896322] #0: 000000008c902cea (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 [ 587.904607] #1: 00000000dc242644 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b70 [ 587.913497] [ 587.915119] ============================================= [ 587.915119] [ 587.922163] NMI backtrace for cpu 0 [ 587.925786] CPU: 0 PID: 1039 Comm: khungtaskd Not tainted 5.0.0-rc5 #60 [ 587.932518] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 587.941854] Call Trace: [ 587.944431] dump_stack+0x172/0x1f0 [ 587.948044] nmi_cpu_backtrace.cold+0x63/0xa4 [ 587.952532] ? lapic_can_unplug_cpu.cold+0x38/0x38 [ 587.957453] nmi_trigger_cpumask_backtrace+0x1be/0x236 [ 587.962729] arch_trigger_cpumask_backtrace+0x14/0x20 [ 587.967908] watchdog+0x9df/0xee0 [ 587.971358] kthread+0x357/0x430 [ 587.974715] ? reset_hung_task_detector+0x30/0x30 [ 587.979615] ? kthread_cancel_delayed_work_sync+0x20/0x20 [ 587.985143] ret_from_fork+0x3a/0x50 [ 587.988915] Sending NMI from CPU 0 to CPUs 1: [ 587.993459] NMI backtrace for cpu 1 skipped: idling at native_safe_halt+0x2/0x10 [ 587.994410] Kernel panic - not syncing: hung_task: blocked tasks [ 588.007335] CPU: 0 PID: 1039 Comm: khungtaskd Not tainted 5.0.0-rc5 #60 [ 588.014075] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 588.023554] Call Trace: [ 588.026142] dump_stack+0x172/0x1f0 [ 588.029754] panic+0x2cb/0x65c [ 588.032937] ? __warn_printk+0xf3/0xf3 [ 588.037082] ? __sanitizer_cov_trace_cmp4+0x16/0x20 [ 588.042086] ? printk_safe_flush+0xf2/0x140 [ 588.046387] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 588.051919] ? lapic_can_unplug_cpu.cold+0x38/0x38 [ 588.056832] ? nmi_trigger_cpumask_backtrace+0x1a7/0x236 [ 588.062266] ? nmi_trigger_cpumask_backtrace+0x19e/0x236 [ 588.067700] watchdog+0x9f0/0xee0 [ 588.071138] kthread+0x357/0x430 [ 588.074484] ? reset_hung_task_detector+0x30/0x30 [ 588.079443] ? kthread_cancel_delayed_work_sync+0x20/0x20 [ 588.084965] ret_from_fork+0x3a/0x50 [ 588.090132] Kernel Offset: disabled [ 588.093759] Rebooting in 86400 seconds..