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 'ci-upstream-next-kasan-gce-9,10.128.15.214' (ECDSA) to the list of known hosts. 2017/08/27 05:11:48 parsed 1 programs 2017/08/27 05:11:48 executed programs: 0 2017/08/27 05:11:53 executed programs: 440 2017/08/27 05:11:58 executed programs: 805 syzkaller login: [ 54.753167] [ 54.754851] ====================================================== [ 54.761144] WARNING: possible circular locking dependency detected [ 54.767440] 4.13.0-rc6-next-20170825+ #9 Not tainted [ 54.772520] ------------------------------------------------------ [ 54.778818] kworker/0:1/23 is trying to acquire lock: [ 54.783984] ((shepherd).work){+.+.}, at: [] process_one_work+0xb2c/0x1be0 [ 54.792557] [ 54.792557] but now in release context of a crosslock acquired at the following: [ 54.801546] ((complete)&rcu.completion){+.+.}, at: [] __synchronize_srcu+0x1b5/0x250 [ 54.811083] [ 54.811083] which lock already depends on the new lock. [ 54.811083] [ 54.819388] [ 54.819388] the existing dependency chain (in reverse order) is: [ 54.826989] [ 54.826989] -> #2 ((complete)&rcu.completion){+.+.}: [ 54.833592] __lock_acquire+0x3286/0x4620 [ 54.838248] lock_acquire+0x1d5/0x580 [ 54.842552] wait_for_completion+0xc8/0x770 [ 54.847368] __synchronize_srcu+0x1b5/0x250 [ 54.852187] synchronize_srcu+0x1a3/0x560 [ 54.856840] quarantine_remove_cache+0xd7/0xf0 [ 54.861926] kasan_cache_shrink+0x9/0x10 [ 54.866491] kmem_cache_shrink+0x15/0x30 [ 54.871042] acpi_os_purge_cache+0x15/0x20 [ 54.875762] acpi_purge_cached_objects+0x38/0xc9 [ 54.881005] acpi_initialize_objects+0xc5/0x112 [ 54.886162] acpi_init+0x23c/0x8e6 [ 54.890186] do_one_initcall+0x9e/0x330 [ 54.894647] kernel_init_freeable+0x469/0x521 [ 54.899627] kernel_init+0x13/0x172 [ 54.903742] ret_from_fork+0x2a/0x40 [ 54.907938] [ 54.907938] -> #1 (cpu_hotplug_lock.rw_sem){++++}: [ 54.914320] __lock_acquire+0x3286/0x4620 [ 54.918953] lock_acquire+0x1d5/0x580 [ 54.923240] cpus_read_lock+0x42/0x90 [ 54.927527] vmstat_shepherd+0x3d/0x1b0 [ 54.931987] process_one_work+0xbfd/0x1be0 [ 54.936713] worker_thread+0x223/0x1860 [ 54.941174] kthread+0x39c/0x470 [ 54.945030] ret_from_fork+0x2a/0x40 [ 54.949228] [ 54.949228] -> #0 ((shepherd).work){+.+.}: [ 54.954909] process_one_work+0xba5/0x1be0 [ 54.959626] worker_thread+0x223/0x1860 [ 54.964087] kthread+0x39c/0x470 [ 54.967941] ret_from_fork+0x2a/0x40 [ 54.972138] 0xffffffffffffffff [ 54.975911] [ 54.975911] other info that might help us debug this: [ 54.975911] [ 54.984017] Chain exists of: [ 54.984017] (shepherd).work --> cpu_hotplug_lock.rw_sem --> (complete)&rcu.completion [ 54.984017] [ 54.996474] Possible unsafe locking scenario by crosslock: [ 54.996474] [ 55.003627] CPU0 CPU1 [ 55.008256] ---- ---- [ 55.012884] lock(cpu_hotplug_lock.rw_sem); [ 55.017254] lock((complete)&rcu.completion); [ 55.021799] lock((shepherd).work); [ 55.027994] unlock((complete)&rcu.completion); [ 55.035234] [ 55.035234] *** DEADLOCK *** [ 55.035234] [ 55.041256] 3 locks held by kworker/0:1/23: [ 55.045539] #0: ("events_power_efficient"){.+.+}, at: [] process_one_work+0xad4/0x1be0 [ 55.055301] #1: ((&(&sdp->work)->work)){+.+.}, at: [] process_one_work+0xb2c/0x1be0 [ 55.064801] #2: (&x->wait#5){....}, at: [] complete+0x18/0x80 [ 55.072390] [ 55.072390] stack backtrace: [ 55.076857] CPU: 0 PID: 23 Comm: kworker/0:1 Not tainted 4.13.0-rc6-next-20170825+ #9 [ 55.084786] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 55.094116] Workqueue: events_power_efficient srcu_invoke_callbacks [ 55.100494] Call Trace: [ 55.103051] dump_stack+0x194/0x257 [ 55.106737] ? arch_local_irq_restore+0x53/0x53 [ 55.111372] print_circular_bug+0x503/0x710 [ 55.115659] ? print_circular_bug_entry+0xb0/0xb0 [ 55.120478] check_prev_add+0x865/0x1520 [ 55.124512] ? graph_lock+0x170/0x170 [ 55.128280] ? check_usage+0xb70/0xb70 [ 55.132136] ? trace_hardirqs_on+0xd/0x10 [ 55.136255] ? detach_if_pending+0x250/0x610 [ 55.140639] ? hlock_class+0x140/0x140 [ 55.144498] lock_commit_crosslock+0xe73/0x1d10 [ 55.149130] ? lock_commit_crosslock+0xe73/0x1d10 [ 55.153939] ? check_prev_add+0x1520/0x1520 [ 55.158225] ? lock_acquire+0x1d5/0x580 [ 55.162164] ? complete+0x18/0x80 [ 55.165593] ? lock_release+0xd70/0xd70 [ 55.169530] ? check_noncircular+0x20/0x20 [ 55.173730] ? do_raw_spin_trylock+0x190/0x190 [ 55.178285] complete+0x24/0x80 [ 55.181531] wakeme_after_rcu+0xd/0x10 [ 55.185383] srcu_invoke_callbacks+0x280/0x4d0 [ 55.189929] ? srcu_queue_delayed_work_on+0x240/0x240 [ 55.195086] ? __lock_is_held+0xbc/0x140 [ 55.199113] process_one_work+0xbfd/0x1be0 [ 55.203310] ? check_noncircular+0x20/0x20 [ 55.207509] ? pwq_dec_nr_in_flight+0x450/0x450 [ 55.212140] ? finish_task_switch+0x1d3/0x740 [ 55.216604] ? __sched_text_start+0x8/0x8 [ 55.220718] ? unwind_dump+0x4c0/0x4c0 [ 55.224571] ? check_noncircular+0x20/0x20 [ 55.228775] ? __unwind_start+0x169/0x330 [ 55.232888] ? find_held_lock+0x39/0x1d0 [ 55.236916] ? lock_acquire+0x1d5/0x580 [ 55.240851] ? worker_thread+0x4a3/0x1860 [ 55.244964] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 55.249683] ? lock_release+0xd70/0xd70 [ 55.253619] ? do_raw_spin_trylock+0x190/0x190 [ 55.258164] ? retint_kernel+0x10/0x10 [ 55.262021] worker_thread+0x223/0x1860 [ 55.265965] ? process_one_work+0x1be0/0x1be0 [ 55.270424] ? check_noncircular+0x20/0x20 [ 55.274622] ? _raw_spin_unlock_irq+0x27/0x70 [ 55.279078] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 55.284057] ? trace_hardirqs_on+0xd/0x10 [ 55.288167] ? _raw_spin_unlock_irq+0x27/0x70 [ 55.292625] ? finish_task_switch+0x1d3/0x740 [ 55.297081] ? finish_task_switch+0x1aa/0x740 [ 55.301539] ? preempt_notifier_dec+0x20/0x20 [ 55.305999] ? __schedule+0x8f0/0x2070 [ 55.309858] ? try_to_wake_up+0xf9/0x1600 [ 55.313969] ? find_held_lock+0x39/0x1d0 [ 55.317997] ? lock_downgrade+0x990/0x990 [ 55.322111] ? complete+0x18/0x80 [ 55.325529] ? __schedule+0x2070/0x2070 [ 55.329469] ? _raw_spin_unlock_irqrestore+0x31/0xba [ 55.334536] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 55.339514] ? trace_hardirqs_on+0xd/0x10 [ 55.343630] ? __kthread_parkme+0x173/0x240 [ 55.347926] kthread+0x39c/0x470 [ 55.351254] ? process_one_work+0x1be0/0x1be0 [ 55.355710] ? kthread_create_on_node+0x100/0x100 [ 55.360516] ret_from_fork+0x2a/0x40