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-0,10.128.0.58' (ECDSA) to the list of known hosts. executing program executing program executing program syzkaller login: [ 42.769134] [ 42.770811] ====================================================== [ 42.777096] WARNING: possible circular locking dependency detected [ 42.783384] 4.13.0-rc6-next-20170825+ #9 Not tainted [ 42.788452] ------------------------------------------------------ [ 42.794736] kworker/0:1/23 is trying to acquire lock: [ 42.799900] ((shepherd).work){+.+.}, at: [] process_one_work+0xb2c/0x1be0 [ 42.808473] [ 42.808473] but now in release context of a crosslock acquired at the following: [ 42.817455] ((complete)&rcu.completion){+.+.}, at: [] __synchronize_srcu+0x1b5/0x250 [ 42.826969] [ 42.826969] which lock already depends on the new lock. [ 42.826969] [ 42.835938] [ 42.835938] the existing dependency chain (in reverse order) is: [ 42.843528] [ 42.843528] -> #2 ((complete)&rcu.completion){+.+.}: [ 42.850088] __lock_acquire+0x3286/0x4620 [ 42.854735] lock_acquire+0x1d5/0x580 [ 42.859024] wait_for_completion+0xc8/0x770 [ 42.863835] __synchronize_srcu+0x1b5/0x250 [ 42.868642] synchronize_srcu+0x1a3/0x560 [ 42.873277] quarantine_remove_cache+0xd7/0xf0 [ 42.878347] kasan_cache_shrink+0x9/0x10 [ 42.882896] kmem_cache_shrink+0x15/0x30 [ 42.887442] acpi_os_purge_cache+0x15/0x20 [ 42.892175] acpi_purge_cached_objects+0x38/0xc9 [ 42.897439] acpi_initialize_objects+0xc5/0x112 [ 42.902595] acpi_init+0x23c/0x8e6 [ 42.906628] do_one_initcall+0x9e/0x330 [ 42.911088] kernel_init_freeable+0x469/0x521 [ 42.916069] kernel_init+0x13/0x172 [ 42.920182] ret_from_fork+0x2a/0x40 [ 42.924390] [ 42.924390] -> #1 (cpu_hotplug_lock.rw_sem){++++}: [ 42.930779] __lock_acquire+0x3286/0x4620 [ 42.935413] lock_acquire+0x1d5/0x580 [ 42.939703] cpus_read_lock+0x42/0x90 [ 42.943990] vmstat_shepherd+0x3d/0x1b0 [ 42.948459] process_one_work+0xbfd/0x1be0 [ 42.953179] worker_thread+0x223/0x1860 [ 42.957638] kthread+0x39c/0x470 [ 42.961491] ret_from_fork+0x2a/0x40 [ 42.965688] [ 42.965688] -> #0 ((shepherd).work){+.+.}: [ 42.971370] process_one_work+0xba5/0x1be0 [ 42.976090] worker_thread+0x223/0x1860 [ 42.980560] kthread+0x39c/0x470 [ 42.984412] ret_from_fork+0x2a/0x40 [ 42.988616] 0xffffffffffffffff [ 42.992378] [ 42.992378] other info that might help us debug this: [ 42.992378] [ 43.000494] Chain exists of: [ 43.000494] (shepherd).work --> cpu_hotplug_lock.rw_sem --> (complete)&rcu.completion [ 43.000494] [ 43.012954] Possible unsafe locking scenario by crosslock: [ 43.012954] [ 43.020104] CPU0 CPU1 [ 43.024733] ---- ---- [ 43.029362] lock(cpu_hotplug_lock.rw_sem); [ 43.033736] lock((complete)&rcu.completion); [ 43.038282] lock((shepherd).work); [ 43.044476] unlock((complete)&rcu.completion); [ 43.051730] [ 43.051730] *** DEADLOCK *** [ 43.051730] [ 43.057761] 3 locks held by kworker/0:1/23: [ 43.062048] #0: ("events_power_efficient"){.+.+}, at: [] process_one_work+0xad4/0x1be0 [ 43.071818] #1: ((&(&sdp->work)->work)){+.+.}, at: [] process_one_work+0xb2c/0x1be0 [ 43.081318] #2: (&x->wait#5){....}, at: [] complete+0x18/0x80 [ 43.088910] [ 43.088910] stack backtrace: [ 43.093373] CPU: 0 PID: 23 Comm: kworker/0:1 Not tainted 4.13.0-rc6-next-20170825+ #9 [ 43.101301] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 43.110629] Workqueue: events_power_efficient srcu_invoke_callbacks [ 43.117018] Call Trace: [ 43.119576] dump_stack+0x194/0x257 [ 43.123169] ? arch_local_irq_restore+0x53/0x53 [ 43.127818] print_circular_bug+0x503/0x710 [ 43.132107] ? print_circular_bug_entry+0xb0/0xb0 [ 43.136924] check_prev_add+0x865/0x1520 [ 43.140958] ? _raw_spin_unlock_irq+0x27/0x70 [ 43.145426] ? graph_lock+0x170/0x170 [ 43.149193] ? check_usage+0xb70/0xb70 [ 43.153046] ? find_held_lock+0x39/0x1d0 [ 43.157074] ? hlock_class+0x140/0x140 [ 43.160928] ? srcu_reschedule+0x130/0x130 [ 43.165139] ? find_next_bit+0x27/0x30 [ 43.168994] lock_commit_crosslock+0xe73/0x1d10 [ 43.174235] ? lock_commit_crosslock+0xe73/0x1d10 [ 43.179055] ? check_prev_add+0x1520/0x1520 [ 43.183346] ? lock_acquire+0x1d5/0x580 [ 43.187284] ? complete+0x18/0x80 [ 43.190704] ? lock_release+0xd70/0xd70 [ 43.194643] ? check_noncircular+0x20/0x20 [ 43.198842] ? do_raw_spin_trylock+0x190/0x190 [ 43.203391] complete+0x24/0x80 [ 43.206635] wakeme_after_rcu+0xd/0x10 [ 43.210487] srcu_invoke_callbacks+0x280/0x4d0 [ 43.215035] ? srcu_queue_delayed_work_on+0x240/0x240 [ 43.220193] ? __lock_is_held+0xbc/0x140 [ 43.224222] process_one_work+0xbfd/0x1be0 [ 43.228423] ? check_noncircular+0x20/0x20 [ 43.232627] ? pwq_dec_nr_in_flight+0x450/0x450 [ 43.237260] ? finish_task_switch+0x1d3/0x740 [ 43.241729] ? __sched_text_start+0x8/0x8 [ 43.245844] ? unwind_dump+0x4c0/0x4c0 [ 43.249699] ? check_noncircular+0x20/0x20 [ 43.253904] ? __unwind_start+0x169/0x330 [ 43.258025] ? find_held_lock+0x39/0x1d0 [ 43.262076] ? lock_acquire+0x1d5/0x580 [ 43.266017] ? worker_thread+0x4a3/0x1860 [ 43.270130] ? lock_release+0xd70/0xd70 [ 43.274068] ? do_raw_spin_trylock+0x190/0x190 [ 43.278614] ? find_held_lock+0x39/0x1d0 [ 43.282644] worker_thread+0x223/0x1860 [ 43.286589] ? process_one_work+0x1be0/0x1be0 [ 43.291074] ? check_noncircular+0x20/0x20 [ 43.295279] ? _raw_spin_unlock_irq+0x27/0x70 [ 43.299738] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 43.304721] ? trace_hardirqs_on+0xd/0x10 [ 43.308835] ? _raw_spin_unlock_irq+0x27/0x70 [ 43.313296] ? finish_task_switch+0x1d3/0x740 [ 43.317756] ? finish_task_switch+0x1aa/0x740 [ 43.322216] ? preempt_notifier_dec+0x20/0x20 [ 43.326679] ? __schedule+0x8f0/0x2070 [ 43.330533] ? try_to_wake_up+0xf9/0x1600 [ 43.334647] ? find_held_lock+0x39/0x1d0 [ 43.338676] ? lock_downgrade+0x990/0x990 [ 43.342790] ? complete+0x18/0x80 [ 43.346210] ? __schedule+0x2070/0x2070 [ 43.350151] ? _raw_spin_unlock_irqrestore+0x31/0xba [ 43.355219] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 43.360201] ? trace_hardirqs_on+0xd/0x10 [ 43.364323] ? __kthread_parkme+0x173/0x240 [ 43.368612] kthread+0x39c/0x470 executing program [ 43.371953] ? process_one_work+0x1be0/0x1be0 [ 43.376415] ? kthread_create_on_node+0x100/0x100 [ 43.381222] ret_from_fork+0x2a/0x40 executing program executing program executing program executing program executing program