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-5,10.128.15.202' (ECDSA) to the list of known hosts. 2017/08/27 15:50:43 parsed 1 programs 2017/08/27 15:50:43 executed programs: 0 2017/08/27 15:50:48 executed programs: 789 2017/08/27 15:50:53 executed programs: 1446 2017/08/27 15:50:58 executed programs: 2095 2017/08/27 15:51:03 executed programs: 2741 2017/08/27 15:51:08 executed programs: 3393 2017/08/27 15:51:13 executed programs: 4051 2017/08/27 15:51:18 executed programs: 4709 2017/08/27 15:51:23 executed programs: 5372 2017/08/27 15:51:28 executed programs: 6035 2017/08/27 15:51:33 executed programs: 6698 2017/08/27 15:51:38 executed programs: 7359 syzkaller login: [ 252.767839] [ 252.769496] ====================================================== [ 252.775781] WARNING: possible circular locking dependency detected [ 252.782073] 4.13.0-rc6-next-20170825+ #9 Not tainted [ 252.787148] ------------------------------------------------------ [ 252.793436] kworker/0:2/1337 is trying to acquire lock: [ 252.798769] ((shepherd).work){+.+.}, at: [] process_one_work+0xb2c/0x1be0 [ 252.807329] [ 252.807329] but now in release context of a crosslock acquired at the following: [ 252.816316] ((complete)wq_barr::done/1){+.+.}, at: [] flush_work+0x621/0x930 [ 252.825132] [ 252.825132] which lock already depends on the new lock. [ 252.825132] [ 252.833430] [ 252.833430] the existing dependency chain (in reverse order) is: [ 252.841033] [ 252.841033] -> #3 ((complete)wq_barr::done/1){+.+.}: [ 252.847615] __lock_acquire+0x3286/0x4620 [ 252.852263] lock_acquire+0x1d5/0x580 [ 252.856552] wait_for_completion+0xc8/0x770 [ 252.861360] flush_work+0x621/0x930 [ 252.865489] lru_add_drain_all_cpuslocked+0x331/0x520 [ 252.871166] lru_add_drain_all+0x13/0x20 [ 252.875715] do_mlock+0x134/0x780 [ 252.879652] SyS_mlock+0x22/0x30 [ 252.883511] entry_SYSCALL_64_fastpath+0x1f/0xbe [ 252.888750] [ 252.888750] -> #2 (lock#4){+.+.}: [ 252.893655] __lock_acquire+0x3286/0x4620 [ 252.898295] lock_acquire+0x1d5/0x580 [ 252.902583] __mutex_lock+0x16f/0x1870 [ 252.906958] mutex_lock_nested+0x16/0x20 [ 252.911505] lru_add_drain_all_cpuslocked+0xb3/0x520 [ 252.917101] lru_add_drain_all+0x13/0x20 [ 252.921650] SyS_mlockall+0x2fb/0x670 [ 252.925941] entry_SYSCALL_64_fastpath+0x1f/0xbe [ 252.931180] [ 252.931180] -> #1 (cpu_hotplug_lock.rw_sem){++++}: [ 252.937561] __lock_acquire+0x3286/0x4620 [ 252.942204] lock_acquire+0x1d5/0x580 [ 252.946493] cpus_read_lock+0x42/0x90 [ 252.950781] vmstat_shepherd+0x3d/0x1b0 [ 252.955244] process_one_work+0xbfd/0x1be0 [ 252.959974] worker_thread+0x223/0x1860 [ 252.964448] kthread+0x39c/0x470 [ 252.968309] ret_from_fork+0x2a/0x40 [ 252.972506] [ 252.972506] -> #0 ((shepherd).work){+.+.}: [ 252.978191] process_one_work+0xba5/0x1be0 [ 252.982913] worker_thread+0x223/0x1860 [ 252.987383] kthread+0x39c/0x470 [ 252.991238] ret_from_fork+0x2a/0x40 [ 252.995439] 0xffffffffffffffff [ 252.999201] [ 252.999201] other info that might help us debug this: [ 252.999201] [ 253.007313] Chain exists of: [ 253.007313] (shepherd).work --> lock#4 --> (complete)wq_barr::done/1 [ 253.007313] [ 253.018386] Possible unsafe locking scenario by crosslock: [ 253.018386] [ 253.025540] CPU0 CPU1 [ 253.030180] ---- ---- [ 253.034810] lock(lock#4); [ 253.037709] lock((complete)wq_barr::done/1); [ 253.042256] lock((shepherd).work); [ 253.048452] unlock((complete)wq_barr::done/1); [ 253.055695] [ 253.055695] *** DEADLOCK *** [ 253.055695] [ 253.061720] 3 locks held by kworker/0:2/1337: [ 253.066177] #0: ("mm_percpu_wq"){++++}, at: [] process_one_work+0xad4/0x1be0 [ 253.075078] #1: ((&barr->work)){+.+.}, at: [] process_one_work+0xb2c/0x1be0 [ 253.083898] #2: (&x->wait#11){....}, at: [] complete+0x18/0x80 [ 253.091579] [ 253.091579] stack backtrace: [ 253.096041] CPU: 0 PID: 1337 Comm: kworker/0:2 Not tainted 4.13.0-rc6-next-20170825+ #9 [ 253.104150] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 253.113488] Workqueue: mm_percpu_wq wq_barrier_func [ 253.118472] Call Trace: [ 253.121033] dump_stack+0x194/0x257 [ 253.124631] ? arch_local_irq_restore+0x53/0x53 [ 253.129278] print_circular_bug+0x503/0x710 [ 253.133592] ? print_circular_bug_entry+0xb0/0xb0 [ 253.138413] check_prev_add+0x865/0x1520 [ 253.142446] ? graph_lock+0x170/0x170 [ 253.146213] ? check_usage+0xb70/0xb70 [ 253.150071] ? add_timer+0x73c/0xf40 [ 253.153751] ? print_usage_bug+0x480/0x480 [ 253.157955] ? hlock_class+0x140/0x140 [ 253.161820] lock_commit_crosslock+0xe73/0x1d10 [ 253.166464] ? lock_commit_crosslock+0xe73/0x1d10 [ 253.171279] ? check_prev_add+0x1520/0x1520 [ 253.175571] ? lock_acquire+0x1d5/0x580 [ 253.179513] ? complete+0x18/0x80 [ 253.182935] ? lock_release+0xd70/0xd70 [ 253.186876] ? process_one_work+0xb2c/0x1be0 [ 253.191264] complete+0x24/0x80 [ 253.194515] wq_barrier_func+0x16/0x20 [ 253.198368] process_one_work+0xbfd/0x1be0 [ 253.202569] ? check_noncircular+0x20/0x20 [ 253.206775] ? pwq_dec_nr_in_flight+0x450/0x450 [ 253.211414] ? finish_task_switch+0x1d3/0x740 [ 253.215896] ? __sched_text_start+0x8/0x8 [ 253.220013] ? check_noncircular+0x20/0x20 [ 253.224227] ? check_noncircular+0x20/0x20 [ 253.228451] ? __unwind_start+0x169/0x330 [ 253.232571] ? check_noncircular+0x20/0x20 [ 253.236774] ? find_held_lock+0x39/0x1d0 [ 253.240807] ? lock_acquire+0x1d5/0x580 [ 253.244747] ? worker_thread+0x4a3/0x1860 [ 253.248866] ? move_linked_works+0x2c8/0x430 [ 253.253242] ? pr_cont_work+0x130/0x130 [ 253.257189] worker_thread+0xa4b/0x1860 [ 253.261132] ? __lock_is_held+0xbc/0x140 [ 253.265173] ? process_one_work+0x1be0/0x1be0 [ 253.269635] ? check_noncircular+0x20/0x20 [ 253.273838] ? _raw_spin_unlock_irq+0x27/0x70 [ 253.278302] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 253.283288] ? trace_hardirqs_on+0xd/0x10 [ 253.287403] ? _raw_spin_unlock_irq+0x27/0x70 [ 253.291869] ? finish_task_switch+0x1d3/0x740 [ 253.296334] ? finish_task_switch+0x1aa/0x740 [ 253.300805] ? preempt_notifier_dec+0x20/0x20 [ 253.305269] ? __schedule+0x8f0/0x2070 [ 253.309217] ? try_to_wake_up+0xf9/0x1600 [ 253.313336] ? find_held_lock+0x39/0x1d0 [ 253.317366] ? lock_downgrade+0x990/0x990 [ 253.321479] ? complete+0x18/0x80 [ 253.324900] ? __schedule+0x2070/0x2070 [ 253.328852] ? _raw_spin_unlock_irqrestore+0x31/0xba [ 253.333924] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 253.338910] ? trace_hardirqs_on+0xd/0x10 [ 253.343027] ? __kthread_parkme+0x173/0x240 [ 253.347315] kthread+0x39c/0x470 [ 253.350650] ? process_one_work+0x1be0/0x1be0 [ 253.355112] ? kthread_create_on_node+0x100/0x100 [ 253.359923] ret_from_fork+0x2a/0x40