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-4,10.128.0.6' (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 syzkaller login: [ 42.744532] [ 42.744864] ====================================================== [ 42.745691] WARNING: possible circular locking dependency detected [ 42.746519] 4.13.0-rc6-next-20170825+ #9 Not tainted [ 42.747207] ------------------------------------------------------ [ 42.748034] kworker/0:1/23 is trying to acquire lock: [ 42.748725] ((shepherd).work){+.+.}, at: [] process_one_work+0xb2c/0x1be0 [ 42.749854] [ 42.749854] but now in release context of a crosslock acquired at the following: [ 42.751041] ((complete)&rcu.completion){+.+.}, at: [] __synchronize_srcu+0x1b5/0x250 [ 42.752337] [ 42.752337] which lock already depends on the new lock. [ 42.752337] [ 42.753524] [ 42.753524] the existing dependency chain (in reverse order) is: [ 42.754577] [ 42.754577] -> #2 ((complete)&rcu.completion){+.+.}: [ 42.755563] __lock_acquire+0x3286/0x4620 [ 42.756199] lock_acquire+0x1d5/0x580 [ 42.756788] wait_for_completion+0xc8/0x770 [ 42.757428] __synchronize_srcu+0x1b5/0x250 [ 42.758117] synchronize_srcu+0x1a3/0x560 [ 42.758735] quarantine_remove_cache+0xd7/0xf0 [ 42.759407] kasan_cache_shrink+0x9/0x10 [ 42.760047] kmem_cache_shrink+0x15/0x30 [ 42.760654] acpi_os_purge_cache+0x15/0x20 [ 42.761312] acpi_purge_cached_objects+0x38/0xc9 [ 42.762010] acpi_initialize_objects+0xc5/0x112 [ 42.762693] acpi_init+0x23c/0x8e6 [ 42.763272] do_one_initcall+0x9e/0x330 [ 42.763868] kernel_init_freeable+0x469/0x521 [ 42.764529] kernel_init+0x13/0x172 [ 42.768076] ret_from_fork+0x2a/0x40 [ 42.772271] [ 42.772271] -> #1 (cpu_hotplug_lock.rw_sem){++++}: [ 42.778654] __lock_acquire+0x3286/0x4620 [ 42.783285] lock_acquire+0x1d5/0x580 [ 42.787570] cpus_read_lock+0x42/0x90 [ 42.791855] vmstat_shepherd+0x3d/0x1b0 [ 42.796318] process_one_work+0xbfd/0x1be0 [ 42.801042] worker_thread+0x223/0x1860 [ 42.805525] kthread+0x39c/0x470 [ 42.809377] ret_from_fork+0x2a/0x40 [ 42.813570] [ 42.813570] -> #0 ((shepherd).work){+.+.}: [ 42.819264] process_one_work+0xba5/0x1be0 [ 42.823988] worker_thread+0x223/0x1860 [ 42.828448] kthread+0x39c/0x470 [ 42.832301] ret_from_fork+0x2a/0x40 [ 42.836499] 0xffffffffffffffff [ 42.840259] [ 42.840259] other info that might help us debug this: [ 42.840259] [ 42.848361] Chain exists of: [ 42.848361] (shepherd).work --> cpu_hotplug_lock.rw_sem --> (complete)&rcu.completion [ 42.848361] [ 42.860814] Possible unsafe locking scenario by crosslock: [ 42.860814] [ 42.867960] CPU0 CPU1 [ 42.872594] ---- ---- [ 42.877221] lock(cpu_hotplug_lock.rw_sem); [ 42.881601] lock((complete)&rcu.completion); [ 42.886149] lock((shepherd).work); [ 42.892341] unlock((complete)&rcu.completion); [ 42.899750] [ 42.899750] *** DEADLOCK *** [ 42.899750] [ 42.905771] 3 locks held by kworker/0:1/23: [ 42.910052] #0: ("events_power_efficient"){.+.+}, at: [] process_one_work+0xad4/0x1be0 [ 42.919818] #1: ((&(&sdp->work)->work)){+.+.}, at: [] process_one_work+0xb2c/0x1be0 [ 42.929403] #2: (&x->wait#5){....}, at: [] complete+0x18/0x80 [ 42.936994] [ 42.936994] stack backtrace: [ 42.941451] CPU: 0 PID: 23 Comm: kworker/0:1 Not tainted 4.13.0-rc6-next-20170825+ #9 [ 42.949385] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 42.958713] Workqueue: events_power_efficient srcu_invoke_callbacks [ 42.965114] Call Trace: [ 42.967671] dump_stack+0x194/0x257 [ 42.971268] ? arch_local_irq_restore+0x53/0x53 [ 42.975904] print_circular_bug+0x503/0x710 [ 42.980190] ? print_circular_bug_entry+0xb0/0xb0 [ 42.984998] check_prev_add+0x865/0x1520 [ 42.989033] ? trace_hardirqs_on+0xd/0x10 [ 42.993146] ? _raw_spin_unlock_irq+0x27/0x70 [ 42.997602] ? graph_lock+0x170/0x170 [ 43.001363] ? check_usage+0xb70/0xb70 [ 43.005213] ? find_held_lock+0x39/0x1d0 [ 43.009247] ? hlock_class+0x140/0x140 [ 43.013097] ? srcu_reschedule+0x130/0x130 [ 43.017292] ? find_next_bit+0x27/0x30 [ 43.021143] lock_commit_crosslock+0xe73/0x1d10 [ 43.025775] ? lock_commit_crosslock+0xe73/0x1d10 [ 43.030584] ? check_prev_add+0x1520/0x1520 [ 43.034873] ? lock_acquire+0x1d5/0x580 [ 43.038817] ? complete+0x18/0x80 [ 43.042242] ? lock_release+0xd70/0xd70 [ 43.046178] ? check_noncircular+0x20/0x20 [ 43.050374] ? do_raw_spin_trylock+0x190/0x190 [ 43.054919] complete+0x24/0x80 [ 43.058160] wakeme_after_rcu+0xd/0x10 [ 43.062008] srcu_invoke_callbacks+0x280/0x4d0 [ 43.066553] ? srcu_queue_delayed_work_on+0x240/0x240 [ 43.071712] ? __lock_is_held+0xbc/0x140 [ 43.075741] process_one_work+0xbfd/0x1be0 [ 43.079938] ? check_noncircular+0x20/0x20 [ 43.084136] ? pwq_dec_nr_in_flight+0x450/0x450 [ 43.088768] ? finish_task_switch+0x1d3/0x740 [ 43.093326] ? __sched_text_start+0x8/0x8 [ 43.097437] ? unwind_dump+0x4c0/0x4c0 [ 43.101288] ? check_noncircular+0x20/0x20 [ 43.105491] ? __unwind_start+0x169/0x330 [ 43.109609] ? find_held_lock+0x39/0x1d0 [ 43.113644] ? lock_acquire+0x1d5/0x580 [ 43.117581] ? worker_thread+0x4a3/0x1860 [ 43.121702] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 43.126421] ? lock_release+0xd70/0xd70 [ 43.130358] ? do_raw_spin_trylock+0x190/0x190 [ 43.134913] ? retint_kernel+0x10/0x10 [ 43.138766] worker_thread+0x223/0x1860 [ 43.142707] ? process_one_work+0x1be0/0x1be0 [ 43.147168] ? check_noncircular+0x20/0x20 [ 43.151366] ? _raw_spin_unlock_irq+0x27/0x70 [ 43.155833] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 43.160812] ? trace_hardirqs_on+0xd/0x10 [ 43.164921] ? _raw_spin_unlock_irq+0x27/0x70 [ 43.169382] ? finish_task_switch+0x1d3/0x740 [ 43.173842] ? finish_task_switch+0x1aa/0x740 [ 43.178300] ? preempt_notifier_dec+0x20/0x20 [ 43.182761] ? __schedule+0x8f0/0x2070 [ 43.186614] ? try_to_wake_up+0xf9/0x1600 [ 43.190726] ? find_held_lock+0x39/0x1d0 executing program [ 43.194766] ? lock_downgrade+0x990/0x990 [ 43.198876] ? complete+0x18/0x80 [ 43.202295] ? __schedule+0x2070/0x2070 [ 43.206231] ? _raw_spin_unlock_irqrestore+0x31/0xba [ 43.211305] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 43.216284] ? trace_hardirqs_on+0xd/0x10 [ 43.220405] ? __kthread_parkme+0x173/0x240 [ 43.224697] kthread+0x39c/0x470 [ 43.228028] ? process_one_work+0x1be0/0x1be0 [ 43.232482] ? kthread_create_on_node+0x100/0x100 [ 43.237289] 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