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-7,10.128.0.18' (ECDSA) to the list of known hosts. executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program syzkaller login: [ 38.752461] [ 38.754098] ====================================================== [ 38.760376] WARNING: possible circular locking dependency detected [ 38.766655] 4.13.0-rc6-next-20170823+ #7 Not tainted [ 38.771719] ------------------------------------------------------ [ 38.777998] kworker/0:2/1336 is trying to acquire lock: [ 38.783323] ((shepherd).work){+.+.}, at: [] process_one_work+0xb2c/0x1be0 [ 38.791884] [ 38.791884] but now in release context of a crosslock acquired at the following: executing program [ 38.800869] ((complete)&rcu.completion){+.+.}, at: [] __synchronize_srcu+0x1b5/0x250 [ 38.810373] [ 38.810373] which lock already depends on the new lock. [ 38.810373] [ 38.818650] [ 38.818650] the existing dependency chain (in reverse order) is: [ 38.826232] [ 38.826232] -> #2 ((complete)&rcu.completion){+.+.}: [ 38.832795] __lock_acquire+0x3286/0x4620 [ 38.837440] lock_acquire+0x1d5/0x580 [ 38.841725] wait_for_completion+0xc8/0x770 [ 38.846548] __synchronize_srcu+0x1b5/0x250 executing program [ 38.851353] synchronize_srcu+0x1a3/0x560 [ 38.855984] quarantine_remove_cache+0xd7/0xf0 [ 38.861084] kasan_cache_shrink+0x9/0x10 [ 38.865644] kmem_cache_shrink+0x15/0x30 [ 38.870204] acpi_os_purge_cache+0x15/0x20 [ 38.874926] acpi_purge_cached_objects+0x38/0xc9 [ 38.880166] acpi_initialize_objects+0xc5/0x112 [ 38.885317] acpi_init+0x23c/0x8e6 [ 38.889339] do_one_initcall+0x9e/0x330 [ 38.893796] kernel_init_freeable+0x46e/0x526 [ 38.898782] kernel_init+0x13/0x172 [ 38.902896] ret_from_fork+0x2a/0x40 [ 38.907089] [ 38.907089] -> #1 (cpu_hotplug_lock.rw_sem){++++}: [ 38.913462] __lock_acquire+0x3286/0x4620 [ 38.918094] lock_acquire+0x1d5/0x580 [ 38.922380] cpus_read_lock+0x42/0x90 [ 38.926667] vmstat_shepherd+0x3d/0x1b0 [ 38.931126] process_one_work+0xbfd/0x1be0 [ 38.935843] worker_thread+0x223/0x1860 [ 38.940301] kthread+0x39c/0x470 [ 38.944178] ret_from_fork+0x2a/0x40 [ 38.948371] executing program [ 38.948371] -> #0 ((shepherd).work){+.+.}: [ 38.954065] process_one_work+0xba5/0x1be0 [ 38.958783] worker_thread+0x223/0x1860 [ 38.963254] kthread+0x39c/0x470 [ 38.967104] ret_from_fork+0x2a/0x40 [ 38.971318] 0xffffffffffffffff [ 38.975078] [ 38.975078] other info that might help us debug this: [ 38.975078] [ 38.983181] Chain exists of: [ 38.983181] (shepherd).work --> cpu_hotplug_lock.rw_sem --> (complete)&rcu.completion [ 38.983181] [ 38.995632] Possible unsafe locking scenario by crosslock: [ 38.995632] executing program [ 39.002779] CPU0 CPU1 [ 39.007418] ---- ---- [ 39.012045] lock(cpu_hotplug_lock.rw_sem); [ 39.016415] lock((complete)&rcu.completion); [ 39.020960] lock((shepherd).work); [ 39.027152] unlock((complete)&rcu.completion); [ 39.034388] [ 39.034388] *** DEADLOCK *** [ 39.034388] [ 39.040408] 3 locks held by kworker/0:2/1336: executing program [ 39.044862] #0: ("events_power_efficient"){.+.+}, at: [] process_one_work+0xad4/0x1be0 [ 39.054621] #1: ((&(&sdp->work)->work)){+.+.}, at: [] process_one_work+0xb2c/0x1be0 [ 39.064117] #2: (&x->wait#5){....}, at: [] complete+0x18/0x80 [ 39.071707] [ 39.071707] stack backtrace: [ 39.076166] CPU: 0 PID: 1336 Comm: kworker/0:2 Not tainted 4.13.0-rc6-next-20170823+ #7 [ 39.084266] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 39.093596] Workqueue: events_power_efficient srcu_invoke_callbacks [ 39.099969] Call Trace: executing program [ 39.102520] dump_stack+0x194/0x257 [ 39.106113] ? arch_local_irq_restore+0x53/0x53 [ 39.110753] print_circular_bug+0x503/0x710 [ 39.115043] ? print_circular_bug_entry+0xb0/0xb0 [ 39.119857] check_prev_add+0x865/0x1520 [ 39.123886] ? _raw_spin_unlock_irq+0x27/0x70 [ 39.128345] ? graph_lock+0x170/0x170 [ 39.132108] ? check_usage+0xb70/0xb70 [ 39.135962] ? find_held_lock+0x39/0x1d0 [ 39.139990] ? hlock_class+0x140/0x140 [ 39.143851] ? lock_downgrade+0x990/0x990 [ 39.147963] ? check_noncircular+0x20/0x20 executing program [ 39.152163] lock_commit_crosslock+0xe73/0x1d10 [ 39.156795] ? lock_commit_crosslock+0xe73/0x1d10 [ 39.161622] ? check_noncircular+0x20/0x20 [ 39.165837] ? check_prev_add+0x1520/0x1520 [ 39.170124] ? lock_acquire+0x1d5/0x580 [ 39.174061] ? complete+0x18/0x80 [ 39.177480] ? lock_release+0xd70/0xd70 [ 39.181419] ? check_noncircular+0x20/0x20 [ 39.185625] ? do_raw_spin_trylock+0x190/0x190 [ 39.190181] complete+0x24/0x80 [ 39.193438] wakeme_after_rcu+0xd/0x10 [ 39.197296] srcu_invoke_callbacks+0x280/0x4d0 executing program [ 39.201843] ? srcu_queue_delayed_work_on+0x240/0x240 [ 39.207007] ? __lock_is_held+0xbc/0x140 [ 39.211036] process_one_work+0xbfd/0x1be0 [ 39.215758] ? check_noncircular+0x20/0x20 [ 39.219959] ? pwq_dec_nr_in_flight+0x450/0x450 [ 39.224599] ? finish_task_switch+0x1d3/0x740 [ 39.229065] ? __sched_text_start+0x8/0x8 [ 39.233178] ? unwind_dump+0x4c0/0x4c0 [ 39.237029] ? check_noncircular+0x20/0x20 [ 39.241226] ? unwind_next_frame+0x3e/0x50 [ 39.245448] ? __save_stack_trace+0x6e/0xd0 [ 39.249740] ? find_held_lock+0x39/0x1d0 [ 39.253774] ? lock_acquire+0x1d5/0x580 [ 39.257732] ? worker_thread+0x4a3/0x1860 [ 39.261848] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 39.266575] ? lock_release+0xd70/0xd70 [ 39.270516] ? do_raw_spin_trylock+0x190/0x190 [ 39.275074] ? retint_kernel+0x10/0x10 [ 39.278953] worker_thread+0x223/0x1860 [ 39.282913] ? process_one_work+0x1be0/0x1be0 [ 39.287377] ? check_noncircular+0x20/0x20 [ 39.291586] ? _raw_spin_unlock_irq+0x27/0x70 [ 39.296065] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 39.301054] ? trace_hardirqs_on+0xd/0x10 [ 39.305169] ? _raw_spin_unlock_irq+0x27/0x70 [ 39.309638] ? finish_task_switch+0x1d3/0x740 [ 39.314104] ? finish_task_switch+0x1aa/0x740 [ 39.318581] ? preempt_notifier_dec+0x20/0x20 [ 39.323051] ? __schedule+0x8f0/0x2070 [ 39.326907] ? try_to_wake_up+0xf9/0x1600 [ 39.331028] ? find_held_lock+0x39/0x1d0 [ 39.335080] ? lock_downgrade+0x990/0x990 [ 39.339246] ? complete+0x18/0x80 [ 39.342684] ? __schedule+0x2070/0x2070 [ 39.346636] ? _raw_spin_unlock_irqrestore+0x31/0xba executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program [ 39.351732] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 39.356719] ? trace_hardirqs_on+0xd/0x10 [ 39.360848] ? __kthread_parkme+0x173/0x240 [ 39.365146] kthread+0x39c/0x470 [ 39.368487] ? process_one_work+0x1be0/0x1be0 [ 39.372953] ? kthread_create_on_node+0x100/0x100 [ 39.377763] ret_from_fork+0x2a/0x40 executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program