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-1,10.128.15.195' (ECDSA) to the list of known hosts. executing program executing program executing program executing program executing program executing program executing program syzkaller login: [ 42.732925] [ 42.734558] ====================================================== [ 42.740851] WARNING: possible circular locking dependency detected [ 42.747148] 4.13.0-rc6-next-20170825+ #9 Not tainted [ 42.752215] ------------------------------------------------------ [ 42.758507] kworker/0:2/1336 is trying to acquire lock: [ 42.763833] ((shepherd).work){+.+.}, at: [] process_one_work+0xb2c/0x1be0 [ 42.772389] [ 42.772389] but now in release context of a crosslock acquired at the following: [ 42.781374] ((complete)&rcu.completion){+.+.}, at: [] __synchronize_srcu+0x1b5/0x250 [ 42.790884] [ 42.790884] which lock already depends on the new lock. [ 42.790884] [ 42.799173] [ 42.799173] the existing dependency chain (in reverse order) is: [ 42.806760] [ 42.806760] -> #2 ((complete)&rcu.completion){+.+.}: [ 42.813322] __lock_acquire+0x3286/0x4620 [ 42.817965] lock_acquire+0x1d5/0x580 [ 42.822263] wait_for_completion+0xc8/0x770 [ 42.827082] __synchronize_srcu+0x1b5/0x250 [ 42.831913] synchronize_srcu+0x1a3/0x560 [ 42.836554] quarantine_remove_cache+0xd7/0xf0 [ 42.841628] kasan_cache_shrink+0x9/0x10 [ 42.846179] kmem_cache_shrink+0x15/0x30 [ 42.850732] acpi_os_purge_cache+0x15/0x20 [ 42.855458] acpi_purge_cached_objects+0x38/0xc9 [ 42.860710] acpi_initialize_objects+0xc5/0x112 [ 42.865872] acpi_init+0x23c/0x8e6 [ 42.869903] do_one_initcall+0x9e/0x330 [ 42.874366] kernel_init_freeable+0x469/0x521 [ 42.879348] kernel_init+0x13/0x172 [ 42.883463] ret_from_fork+0x2a/0x40 [ 42.887660] [ 42.887660] -> #1 (cpu_hotplug_lock.rw_sem){++++}: [ 42.894047] __lock_acquire+0x3286/0x4620 [ 42.898684] lock_acquire+0x1d5/0x580 [ 42.902973] cpus_read_lock+0x42/0x90 [ 42.907261] vmstat_shepherd+0x3d/0x1b0 [ 42.911720] process_one_work+0xbfd/0x1be0 [ 42.916439] worker_thread+0x223/0x1860 [ 42.920903] kthread+0x39c/0x470 [ 42.924758] ret_from_fork+0x2a/0x40 [ 42.928956] [ 42.928956] -> #0 ((shepherd).work){+.+.}: [ 42.934643] process_one_work+0xba5/0x1be0 [ 42.939366] worker_thread+0x223/0x1860 [ 42.943830] kthread+0x39c/0x470 [ 42.947689] ret_from_fork+0x2a/0x40 [ 42.951889] 0xffffffffffffffff [ 42.955662] [ 42.955662] other info that might help us debug this: [ 42.955662] [ 42.963777] Chain exists of: [ 42.963777] (shepherd).work --> cpu_hotplug_lock.rw_sem --> (complete)&rcu.completion [ 42.963777] [ 42.976240] Possible unsafe locking scenario by crosslock: [ 42.976240] [ 42.983392] CPU0 CPU1 [ 42.988027] ---- ---- [ 42.992654] lock(cpu_hotplug_lock.rw_sem); [ 42.997028] lock((complete)&rcu.completion); [ 43.001573] lock((shepherd).work); [ 43.007770] unlock((complete)&rcu.completion); [ 43.015005] [ 43.015005] *** DEADLOCK *** [ 43.015005] [ 43.021214] 3 locks held by kworker/0:2/1336: [ 43.025669] #0: ("events_power_efficient"){.+.+}, at: [] process_one_work+0xad4/0x1be0 [ 43.035433] #1: ((&(&sdp->work)->work)){+.+.}, at: [] process_one_work+0xb2c/0x1be0 [ 43.044936] #2: (&x->wait#5){....}, at: [] complete+0x18/0x80 [ 43.052530] [ 43.052530] stack backtrace: [ 43.056992] CPU: 0 PID: 1336 Comm: kworker/0:2 Not tainted 4.13.0-rc6-next-20170825+ #9 [ 43.065093] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 43.074421] Workqueue: events_power_efficient srcu_invoke_callbacks [ 43.080798] Call Trace: [ 43.083356] dump_stack+0x194/0x257 [ 43.086950] ? arch_local_irq_restore+0x53/0x53 [ 43.091586] print_circular_bug+0x503/0x710 [ 43.095875] ? print_circular_bug_entry+0xb0/0xb0 [ 43.100685] check_prev_add+0x865/0x1520 [ 43.104712] ? trace_hardirqs_on+0xd/0x10 [ 43.108827] ? _raw_spin_unlock_irq+0x27/0x70 [ 43.113286] ? graph_lock+0x170/0x170 [ 43.117050] ? check_usage+0xb70/0xb70 [ 43.120904] ? find_held_lock+0x39/0x1d0 [ 43.124932] ? hlock_class+0x140/0x140 [ 43.128783] ? srcu_reschedule+0x130/0x130 [ 43.132982] ? find_next_bit+0x27/0x30 [ 43.136836] lock_commit_crosslock+0xe73/0x1d10 [ 43.141470] ? lock_commit_crosslock+0xe73/0x1d10 [ 43.146287] ? check_prev_add+0x1520/0x1520 [ 43.150578] ? lock_acquire+0x1d5/0x580 [ 43.154514] ? complete+0x18/0x80 [ 43.157935] ? lock_release+0xd70/0xd70 [ 43.161873] ? check_noncircular+0x20/0x20 [ 43.166077] ? do_raw_spin_trylock+0x190/0x190 [ 43.170646] complete+0x24/0x80 [ 43.173894] wakeme_after_rcu+0xd/0x10 [ 43.177750] srcu_invoke_callbacks+0x280/0x4d0 [ 43.182299] ? srcu_queue_delayed_work_on+0x240/0x240 [ 43.187457] ? __lock_is_held+0xbc/0x140 [ 43.191487] process_one_work+0xbfd/0x1be0 [ 43.195686] ? check_noncircular+0x20/0x20 [ 43.199888] ? pwq_dec_nr_in_flight+0x450/0x450 [ 43.204527] ? finish_task_switch+0x1d3/0x740 [ 43.208997] ? __sched_text_start+0x8/0x8 [ 43.213111] ? check_noncircular+0x20/0x20 [ 43.217308] ? check_noncircular+0x20/0x20 [ 43.221506] ? __unwind_start+0x169/0x330 [ 43.225619] ? check_noncircular+0x20/0x20 [ 43.229820] ? find_held_lock+0x39/0x1d0 [ 43.233850] ? lock_acquire+0x1d5/0x580 [ 43.237786] ? worker_thread+0x4a3/0x1860 [ 43.241904] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 43.246626] ? lock_release+0xd70/0xd70 [ 43.250565] ? do_raw_spin_trylock+0x190/0x190 [ 43.255114] ? retint_kernel+0x10/0x10 [ 43.258972] worker_thread+0x223/0x1860 [ 43.262921] ? __lock_is_held+0xbc/0x140 [ 43.266950] ? process_one_work+0x1be0/0x1be0 [ 43.271411] ? check_noncircular+0x20/0x20 [ 43.275615] ? _raw_spin_unlock_irq+0x27/0x70 [ 43.280088] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 43.285068] ? trace_hardirqs_on+0xd/0x10 [ 43.289187] ? _raw_spin_unlock_irq+0x27/0x70 [ 43.293650] ? finish_task_switch+0x1d3/0x740 [ 43.298110] ? finish_task_switch+0x1aa/0x740 [ 43.302571] ? preempt_notifier_dec+0x20/0x20 [ 43.307034] ? __schedule+0x8f0/0x2070 [ 43.310886] ? try_to_wake_up+0xf9/0x1600 [ 43.315003] ? find_held_lock+0x39/0x1d0 [ 43.319040] ? lock_downgrade+0x990/0x990 [ 43.323154] ? complete+0x18/0x80 [ 43.326573] ? __schedule+0x2070/0x2070 [ 43.330520] ? _raw_spin_unlock_irqrestore+0x31/0xba executing program [ 43.335590] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 43.340572] ? trace_hardirqs_on+0xd/0x10 [ 43.344686] ? __kthread_parkme+0x173/0x240 [ 43.348979] kthread+0x39c/0x470 [ 43.352308] ? process_one_work+0x1be0/0x1be0 [ 43.356768] ? kthread_create_on_node+0x100/0x100 [ 43.361580] ret_from_fork+0x2a/0x40 executing program executing program executing program executing program executing program executing program executing program