net.ipv6.conf.syz4.accept_dad = 0 net.ipv6.conf.syz0.accept_dad = 0 net.ipv6.conf.syz3.accept_dad = 0 net.ipv6.conf.syz6.accept_dad = 0 net.ipv6.conf.syz1.accept_dad = 0 net.ipv6.conf.syz7.accept_dad = 0 net.ipv6.conf.syz5.accept_dad = 0 net.ipv6.conf.syz0.router_solicitations = 0 net.ipv6.conf.syz4.router_solicitations = 0 net.ipv6.conf.syz2.accept_dad = 0 net.ipv6.conf.syz6.router_solicitations = 0 net.ipv6.conf.syz3.router_solicitations = 0 net.ipv6.conf.syz7.router_solicitations = 0 net.ipv6.conf.syz5.router_solicitations = 0 net.ipv6.conf.syz2.router_solicitations = 0 net.ipv6.conf.syz1.router_solicitations = 0 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 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 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 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 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: [ 35.777386] [ 35.777547] ====================================================== [ 35.778055] WARNING: possible circular locking dependency detected [ 35.778568] 4.13.0-rc6-next-20170824+ #8 Not tainted executing program [ 35.778988] ------------------------------------------------------ [ 35.787190] kworker/0:2/1313 is trying to acquire lock: [ 35.787728] ((shepherd).work){+.+.}, at: [] process_one_work+0xb2c/0x1be0 [ 35.788483] [ 35.788483] but now in release context of a crosslock acquired at the following: [ 35.789269] ((complete)&rcu.completion){+.+.}, at: [] __synchronize_srcu+0x1b5/0x250 [ 35.790107] [ 35.790107] which lock already depends on the new lock. [ 35.790107] [ 35.790813] [ 35.790813] the existing dependency chain (in reverse order) is: [ 35.791549] [ 35.791549] -> #2 ((complete)&rcu.completion){+.+.}: [ 35.792327] __lock_acquire+0x3286/0x4620 [ 35.792723] lock_acquire+0x1d5/0x580 [ 35.793117] wait_for_completion+0xc8/0x770 [ 35.793610] __synchronize_srcu+0x1b5/0x250 [ 35.794084] synchronize_srcu+0x1a3/0x560 [ 35.794490] quarantine_remove_cache+0xd7/0xf0 [ 35.794912] kasan_cache_shrink+0x9/0x10 [ 35.795384] kmem_cache_shrink+0x15/0x30 [ 35.795861] acpi_os_purge_cache+0x15/0x20 [ 35.796294] acpi_purge_cached_objects+0x38/0xc9 [ 35.796745] acpi_initialize_objects+0xc5/0x112 [ 35.797227] acpi_init+0x23c/0x8e6 [ 35.797645] do_one_initcall+0x9e/0x330 [ 35.798089] kernel_init_freeable+0x469/0x521 [ 35.798532] kernel_init+0x13/0x172 [ 35.798877] ret_from_fork+0x2a/0x40 [ 35.799285] [ 35.799285] -> #1 (cpu_hotplug_lock.rw_sem){++++}: [ 35.800251] __lock_acquire+0x3286/0x4620 [ 35.800725] lock_acquire+0x1d5/0x580 [ 35.801187] cpus_read_lock+0x42/0x90 [ 35.801551] vmstat_shepherd+0x3d/0x1b0 [ 35.801941] process_one_work+0xbfd/0x1be0 [ 35.802347] worker_thread+0x223/0x1860 [ 35.802714] kthread+0x39c/0x470 [ 35.803156] ret_from_fork+0x2a/0x40 [ 35.803480] [ 35.803480] -> #0 ((shepherd).work){+.+.}: [ 35.803940] process_one_work+0xba5/0x1be0 [ 35.814109] worker_thread+0x223/0x1860 [ 35.814445] kthread+0x39c/0x470 [ 35.814739] ret_from_fork+0x2a/0x40 [ 35.815648] 0xffffffffffffffff [ 35.815887] [ 35.815887] other info that might help us debug this: [ 35.815887] [ 35.816637] Chain exists of: [ 35.816637] (shepherd).work --> cpu_hotplug_lock.rw_sem --> (complete)&rcu.completion [ 35.816637] [ 35.817670] Possible unsafe locking scenario by crosslock: [ 35.817670] [ 35.818337] CPU0 CPU1 [ 35.818738] ---- ---- [ 35.819297] lock(cpu_hotplug_lock.rw_sem); [ 35.819678] lock((complete)&rcu.completion); [ 35.820330] lock((shepherd).work); [ 35.827345] unlock((complete)&rcu.completion); [ 35.828476] [ 35.828476] *** DEADLOCK *** [ 35.828476] [ 35.829082] 3 locks held by kworker/0:2/1313: [ 35.829518] #0: ("events_power_efficient"){.+.+}, at: [] process_one_work+0xad4/0x1be0 [ 35.830640] #1: ((&(&sdp->work)->work)){+.+.}, at: [] process_one_work+0xb2c/0x1be0 [ 35.831599] #2: (&x->wait#5){....}, at: [] complete+0x18/0x80 [ 35.832194] [ 35.832194] stack backtrace: [ 35.832522] CPU: 0 PID: 1313 Comm: kworker/0:2 Not tainted 4.13.0-rc6-next-20170824+ #8 [ 35.833233] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 [ 35.834038] Workqueue: events_power_efficient srcu_invoke_callbacks [ 35.834748] Call Trace: [ 35.835018] dump_stack+0x194/0x257 [ 35.835397] ? arch_local_irq_restore+0x53/0x53 [ 35.835880] print_circular_bug+0x503/0x710 [ 35.836254] ? print_circular_bug_entry+0xb0/0xb0 [ 35.836643] check_prev_add+0x865/0x1520 [ 35.836945] ? trace_hardirqs_on+0xd/0x10 [ 35.837498] ? _raw_spin_unlock_irq+0x27/0x70 [ 35.837955] ? graph_lock+0x170/0x170 [ 35.838350] ? check_usage+0xb70/0xb70 [ 35.838755] ? find_held_lock+0x39/0x1d0 [ 35.839194] ? hlock_class+0x140/0x140 [ 35.839603] ? srcu_reschedule+0x130/0x130 [ 35.840047] ? find_next_bit+0x27/0x30 [ 35.840455] lock_commit_crosslock+0xe73/0x1d10 [ 35.841168] ? lock_commit_crosslock+0xe73/0x1d10 [ 35.841998] ? check_prev_add+0x1520/0x1520 [ 35.842873] ? lock_acquire+0x1d5/0x580 [ 35.843604] ? complete+0x18/0x80 [ 35.844311] ? lock_release+0xd70/0xd70 [ 35.844985] ? check_noncircular+0x20/0x20 [ 35.845632] ? do_raw_spin_trylock+0x190/0x190 [ 35.846430] complete+0x24/0x80 [ 35.848291] wakeme_after_rcu+0xd/0x10 [ 35.851623] srcu_invoke_callbacks+0x280/0x4d0 [ 35.852041] ? srcu_queue_delayed_work_on+0x240/0x240 [ 35.852781] ? __lock_is_held+0xbc/0x140 [ 35.854163] process_one_work+0xbfd/0x1be0 [ 35.854936] ? check_noncircular+0x20/0x20 [ 35.855752] ? pwq_dec_nr_in_flight+0x450/0x450 [ 35.856610] ? finish_task_switch+0x1d3/0x740 [ 35.857793] ? __sched_text_start+0x8/0x8 [ 35.858547] ? check_noncircular+0x20/0x20 [ 35.859376] ? __unwind_start+0x169/0x330 [ 35.860173] ? find_held_lock+0x39/0x1d0 [ 35.860933] ? lock_acquire+0x1d5/0x580 [ 35.861581] ? worker_thread+0x4a3/0x1860 [ 35.862332] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 35.863338] ? lock_release+0xd70/0xd70 [ 35.864497] ? do_raw_spin_trylock+0x190/0x190 [ 35.865340] ? retint_kernel+0x10/0x10 [ 35.865961] worker_thread+0x223/0x1860 [ 35.866932] ? process_one_work+0x1be0/0x1be0 [ 35.868053] ? check_noncircular+0x20/0x20 [ 35.870192] ? _raw_spin_unlock_irq+0x27/0x70 [ 35.870623] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 35.871741] ? trace_hardirqs_on+0xd/0x10 [ 35.873565] ? _raw_spin_unlock_irq+0x27/0x70 [ 35.873978] ? finish_task_switch+0x1d3/0x740 [ 35.874663] ? finish_task_switch+0x1aa/0x740 [ 35.875977] ? preempt_notifier_dec+0x20/0x20 [ 35.876332] ? __schedule+0x8f0/0x2070 [ 35.876624] ? __x2apic_send_IPI_dest.constprop.7+0x5b/0x80 [ 35.877230] ? try_to_wake_up+0xf9/0x1600 [ 35.877803] ? find_held_lock+0x39/0x1d0 [ 35.878504] ? lock_downgrade+0x990/0x990 [ 35.879207] ? complete+0x18/0x80 [ 35.879783] ? __schedule+0x2070/0x2070 [ 35.880465] ? _raw_spin_unlock_irqrestore+0x31/0xba [ 35.881230] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 35.881891] ? trace_hardirqs_on+0xd/0x10 [ 35.882436] ? __kthread_parkme+0x173/0x240 [ 35.883019] kthread+0x39c/0x470 [ 35.883471] ? process_one_work+0x1be0/0x1be0 [ 35.884072] ? kthread_create_on_node+0x100/0x100 [ 35.884771] 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 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