[ OK ] Reached target Login Prompts. [ OK ] Reached target Multi-User System. [ OK ] Reached target Graphical Interface. Starting Update UTMP about System Runlevel Changes... [ OK ] Started Update UTMP about System Runlevel Changes. Debian GNU/Linux 9 syzkaller ttyS0 Warning: Permanently added '10.128.0.226' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 487.192525][ T8438] block nbd0: shutting down sockets [ 715.688944][ T1656] INFO: task syz-executor694:8438 blocked for more than 143 seconds. [ 715.697323][ T1656] Not tainted 5.14.0-rc6-syzkaller #0 [ 715.703699][ T1656] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 715.712449][ T1656] task:syz-executor694 state:D stack:27528 pid: 8438 ppid: 8437 flags:0x00004004 [ 715.721735][ T1656] Call Trace: [ 715.725006][ T1656] __schedule+0x93a/0x26f0 [ 715.729709][ T1656] ? io_schedule_timeout+0x140/0x140 [ 715.734994][ T1656] schedule+0xd3/0x270 [ 715.739109][ T1656] schedule_timeout+0x1db/0x2a0 [ 715.743959][ T1656] ? usleep_range+0x170/0x170 [ 715.748715][ T1656] ? wait_for_completion+0x16e/0x280 [ 715.754081][ T1656] ? lock_downgrade+0x6e0/0x6e0 [ 715.758973][ T1656] ? do_raw_spin_lock+0x120/0x2b0 [ 715.763994][ T1656] ? rwlock_bug.part.0+0x90/0x90 [ 715.769154][ T1656] ? _raw_spin_unlock_irq+0x1f/0x40 [ 715.774439][ T1656] wait_for_completion+0x176/0x280 [ 715.779601][ T1656] ? __mutex_unlock_slowpath+0xe2/0x610 [ 715.785144][ T1656] ? bit_wait_io_timeout+0x160/0x160 [ 715.790496][ T1656] ? flush_workqueue_prep_pwqs+0x2ae/0x510 [ 715.796297][ T1656] ? __sanitizer_cov_trace_const_cmp4+0x1c/0x70 [ 715.802574][ T1656] ? check_flush_dependency+0x86/0x400 [ 715.808211][ T1656] flush_workqueue+0x3ff/0x1600 [ 715.813148][ T1656] ? __dev_printk+0xcf/0xf5 [ 715.817652][ T1656] ? dev_err_probe.cold+0x21/0x21 [ 715.822719][ T1656] ? check_flush_dependency+0x400/0x400 [ 715.828368][ T1656] ? sock_shutdown.cold+0x62/0x6e [ 715.833452][ T1656] nbd_ioctl+0x60e/0xa50 [ 715.837694][ T1656] ? nbd_release+0x1a0/0x1a0 [ 715.842353][ T1656] ? finish_wait+0x270/0x270 [ 715.846956][ T1656] ? find_held_lock+0x2d/0x110 [ 715.851825][ T1656] ? nbd_release+0x1a0/0x1a0 [ 715.856418][ T1656] blkdev_ioctl+0x2a1/0x6d0 [ 715.861026][ T1656] ? blkdev_common_ioctl+0x1830/0x1830 [ 715.866603][ T1656] block_ioctl+0xf9/0x140 [ 715.871098][ T1656] ? bd_unlink_disk_holder+0x430/0x430 [ 715.876568][ T1656] __x64_sys_ioctl+0x193/0x200 [ 715.881398][ T1656] do_syscall_64+0x35/0xb0 [ 715.885812][ T1656] entry_SYSCALL_64_after_hwframe+0x44/0xae [ 715.891767][ T1656] RIP: 0033:0x4441e9 [ 715.895650][ T1656] RSP: 002b:00007ffdb87c2538 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 [ 715.904261][ T1656] RAX: ffffffffffffffda RBX: 00000000004004a0 RCX: 00000000004441e9 [ 715.912300][ T1656] RDX: 0000000000000000 RSI: 000000000000ab03 RDI: 0000000000000003 [ 715.920328][ T1656] RBP: 0000000000000000 R08: 00007ffdb87c26d8 R09: 00007ffdb87c26d8 [ 715.928301][ T1656] R10: 00007ffdb87c26d8 R11: 0000000000000246 R12: 0000000000403500 [ 715.936350][ T1656] R13: 431bde82d7b634db R14: 00000000004b2018 R15: 00000000004004a0 [ 715.944443][ T1656] [ 715.944443][ T1656] Showing all locks held in the system: [ 715.952244][ T1656] 1 lock held by khungtaskd/1656: [ 715.957262][ T1656] #0: ffffffff8b97c280 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x260 [ 715.967164][ T1656] 3 locks held by kworker/u5:0/2036: [ 715.972544][ T1656] #0: ffff888020801138 ((wq_completion)knbd0-recv){+.+.}-{0:0}, at: process_one_work+0x871/0x1630 [ 715.983418][ T1656] #1: ffffc9000778fdb0 ((work_completion)(&args->work)){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1630 [ 715.994664][ T1656] #2: ffff8880327d3120 (sk_lock-AF_AX25){+.+.}-{0:0}, at: ax25_recvmsg+0xbc/0x850 [ 716.004096][ T1656] 1 lock held by in:imklog/8141: [ 716.009092][ T1656] #0: ffff8880173c7270 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xe9/0x100 [ 716.018229][ T1656] [ 716.020587][ T1656] ============================================= [ 716.020587][ T1656] [ 716.029057][ T1656] NMI backtrace for cpu 0 [ 716.033374][ T1656] CPU: 0 PID: 1656 Comm: khungtaskd Not tainted 5.14.0-rc6-syzkaller #0 [ 716.041678][ T1656] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 716.051713][ T1656] Call Trace: [ 716.054979][ T1656] dump_stack_lvl+0xcd/0x134 [ 716.059554][ T1656] nmi_cpu_backtrace.cold+0x44/0xd7 [ 716.064726][ T1656] ? lapic_can_unplug_cpu+0x80/0x80 [ 716.069901][ T1656] nmi_trigger_cpumask_backtrace+0x1b3/0x230 [ 716.075864][ T1656] watchdog+0xd0a/0xfc0 [ 716.079997][ T1656] ? reset_hung_task_detector+0x30/0x30 [ 716.085520][ T1656] kthread+0x3e5/0x4d0 [ 716.089567][ T1656] ? set_kthread_struct+0x130/0x130 [ 716.094745][ T1656] ret_from_fork+0x1f/0x30 [ 716.099267][ T1656] Sending NMI from CPU 0 to CPUs 1: [ 716.104585][ C1] NMI backtrace for cpu 1 skipped: idling at acpi_idle_do_entry+0x1c6/0x250 [ 716.105587][ T1656] Kernel panic - not syncing: hung_task: blocked tasks [ 716.120281][ T1656] CPU: 0 PID: 1656 Comm: khungtaskd Not tainted 5.14.0-rc6-syzkaller #0 [ 716.128593][ T1656] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 716.138634][ T1656] Call Trace: [ 716.141906][ T1656] dump_stack_lvl+0xcd/0x134 [ 716.146493][ T1656] panic+0x306/0x73d [ 716.150372][ T1656] ? __warn_printk+0xf3/0xf3 [ 716.154949][ T1656] ? lapic_can_unplug_cpu+0x80/0x80 [ 716.160145][ T1656] ? preempt_schedule_thunk+0x16/0x18 [ 716.165536][ T1656] ? nmi_trigger_cpumask_backtrace+0x196/0x230 [ 716.171682][ T1656] ? watchdog.cold+0x5/0x158 [ 716.176264][ T1656] watchdog.cold+0x16/0x158 [ 716.180755][ T1656] ? reset_hung_task_detector+0x30/0x30 [ 716.186462][ T1656] kthread+0x3e5/0x4d0 [ 716.190513][ T1656] ? set_kthread_struct+0x130/0x130 [ 716.195695][ T1656] ret_from_fork+0x1f/0x30 [ 716.206439][ T1656] Kernel Offset: disabled [ 716.210746][ T1656] Rebooting in 86400 seconds..