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-5,10.128.0.13' (ECDSA) to the list of known hosts. 2017/08/25 06:38:19 parsed 1 programs 2017/08/25 06:38:19 executed programs: 0 2017/08/25 06:38:24 executed programs: 497 2017/08/25 06:38:29 executed programs: 947 2017/08/25 06:38:34 executed programs: 1399 2017/08/25 06:38:39 executed programs: 1850 2017/08/25 06:38:44 executed programs: 2301 2017/08/25 06:38:49 executed programs: 2755 2017/08/25 06:38:54 executed programs: 3201 2017/08/25 06:38:59 executed programs: 3650 syzkaller login: [ 162.719228] [ 162.720885] ====================================================== [ 162.727166] WARNING: possible circular locking dependency detected [ 162.733448] 4.13.0-rc6-next-20170824+ #8 Not tainted [ 162.738513] ------------------------------------------------------ [ 162.744795] kworker/0:2/1694 is trying to acquire lock: [ 162.750119] ((shepherd).work){+.+.}, at: [] process_one_work+0xb2c/0x1be0 [ 162.758675] [ 162.758675] but now in release context of a crosslock acquired at the following: [ 162.767647] ((complete)wq_barr::done/1){+.+.}, at: [] flush_work+0x621/0x930 [ 162.776462] [ 162.776462] which lock already depends on the new lock. [ 162.776462] [ 162.784741] [ 162.784741] the existing dependency chain (in reverse order) is: [ 162.792335] [ 162.792335] -> #3 ((complete)wq_barr::done/1){+.+.}: [ 162.798902] __lock_acquire+0x3286/0x4620 [ 162.803538] lock_acquire+0x1d5/0x580 [ 162.807825] wait_for_completion+0xc8/0x770 [ 162.812632] flush_work+0x621/0x930 [ 162.816747] lru_add_drain_all_cpuslocked+0x331/0x520 [ 162.822423] lru_add_drain_all+0x13/0x20 [ 162.826971] do_mlock+0x134/0x780 [ 162.830918] SyS_mlock2+0x4b/0x70 [ 162.834860] entry_SYSCALL_64_fastpath+0x1f/0xbe [ 162.840100] [ 162.840100] -> #2 (lock#4){+.+.}: [ 162.845007] __lock_acquire+0x3286/0x4620 [ 162.849649] lock_acquire+0x1d5/0x580 [ 162.853936] __mutex_lock+0x16f/0x1870 [ 162.858309] mutex_lock_nested+0x16/0x20 [ 162.862867] lru_add_drain_all_cpuslocked+0xb3/0x520 [ 162.868459] lru_add_drain_all+0x13/0x20 [ 162.873011] SyS_mlockall+0x2fb/0x670 [ 162.877308] entry_SYSCALL_64_fastpath+0x1f/0xbe [ 162.882549] [ 162.882549] -> #1 (cpu_hotplug_lock.rw_sem){++++}: [ 162.888931] __lock_acquire+0x3286/0x4620 [ 162.893566] lock_acquire+0x1d5/0x580 [ 162.897862] cpus_read_lock+0x42/0x90 [ 162.902158] vmstat_shepherd+0x3d/0x1b0 [ 162.906617] process_one_work+0xbfd/0x1be0 [ 162.911337] worker_thread+0x223/0x1860 [ 162.915797] kthread+0x39c/0x470 [ 162.919652] ret_from_fork+0x2a/0x40 [ 162.923850] [ 162.923850] -> #0 ((shepherd).work){+.+.}: [ 162.929549] process_one_work+0xba5/0x1be0 [ 162.934273] worker_thread+0x223/0x1860 [ 162.938734] kthread+0x39c/0x470 [ 162.942591] ret_from_fork+0x2a/0x40 [ 162.946796] 0xffffffffffffffff [ 162.950556] [ 162.950556] other info that might help us debug this: [ 162.950556] [ 162.958670] Chain exists of: [ 162.958670] (shepherd).work --> lock#4 --> (complete)wq_barr::done/1 [ 162.958670] [ 162.969656] Possible unsafe locking scenario by crosslock: [ 162.969656] [ 162.976807] CPU0 CPU1 [ 162.981448] ---- ---- [ 162.986086] lock(lock#4); [ 162.988988] lock((complete)wq_barr::done/1); [ 162.993543] lock((shepherd).work); [ 162.999737] unlock((complete)wq_barr::done/1); [ 163.006978] [ 163.006978] *** DEADLOCK *** [ 163.006978] [ 163.013009] 3 locks held by kworker/0:2/1694: [ 163.017472] #0: ("mm_percpu_wq"){++++}, at: [] process_one_work+0xad4/0x1be0 [ 163.026371] #1: ((&barr->work)){+.+.}, at: [] process_one_work+0xb2c/0x1be0 [ 163.035182] #2: (&x->wait#11){....}, at: [] complete+0x18/0x80 [ 163.042864] [ 163.042864] stack backtrace: [ 163.047328] CPU: 0 PID: 1694 Comm: kworker/0:2 Not tainted 4.13.0-rc6-next-20170824+ #8 [ 163.055433] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 163.064771] Workqueue: mm_percpu_wq wq_barrier_func [ 163.069758] Call Trace: [ 163.072312] dump_stack+0x194/0x257 [ 163.075914] ? arch_local_irq_restore+0x53/0x53 [ 163.080553] print_circular_bug+0x503/0x710 [ 163.084851] ? print_circular_bug_entry+0xb0/0xb0 [ 163.089664] check_prev_add+0x865/0x1520 [ 163.093696] ? __pagevec_lru_add_fn+0x783/0xf40 [ 163.098332] ? graph_lock+0x170/0x170 [ 163.102101] ? check_usage+0xb70/0xb70 [ 163.105955] ? print_usage_bug+0x480/0x480 [ 163.110158] ? hlock_class+0x140/0x140 [ 163.114026] lock_commit_crosslock+0xe73/0x1d10 [ 163.118664] ? lock_commit_crosslock+0xe73/0x1d10 [ 163.123475] ? check_prev_add+0x1520/0x1520 [ 163.127765] ? lock_acquire+0x1d5/0x580 [ 163.131705] ? complete+0x18/0x80 [ 163.135128] ? lock_release+0xd70/0xd70 [ 163.139066] ? process_one_work+0xb2c/0x1be0 [ 163.143445] complete+0x24/0x80 [ 163.146692] wq_barrier_func+0x16/0x20 [ 163.150551] process_one_work+0xbfd/0x1be0 [ 163.154755] ? check_noncircular+0x20/0x20 [ 163.158960] ? pwq_dec_nr_in_flight+0x450/0x450 [ 163.163603] ? finish_task_switch+0x1d3/0x740 [ 163.168073] ? __sched_text_start+0x8/0x8 [ 163.172193] ? unwind_dump+0x4c0/0x4c0 [ 163.176048] ? check_noncircular+0x20/0x20 [ 163.180247] ? __unwind_start+0x169/0x330 [ 163.184367] ? find_held_lock+0x39/0x1d0 [ 163.188397] ? lock_acquire+0x1d5/0x580 [ 163.192339] ? worker_thread+0x4a3/0x1860 [ 163.196454] ? move_linked_works+0x2c8/0x430 [ 163.200833] ? pr_cont_work+0x130/0x130 [ 163.204787] worker_thread+0xa4b/0x1860 [ 163.208734] ? process_one_work+0x1be0/0x1be0 [ 163.213196] ? check_noncircular+0x20/0x20 [ 163.217398] ? _raw_spin_unlock_irq+0x27/0x70 [ 163.221863] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 163.226853] ? trace_hardirqs_on+0xd/0x10 [ 163.230970] ? _raw_spin_unlock_irq+0x27/0x70 [ 163.235443] ? finish_task_switch+0x1d3/0x740 [ 163.239906] ? finish_task_switch+0x1aa/0x740 [ 163.244930] ? preempt_notifier_dec+0x20/0x20 [ 163.249398] ? __schedule+0x8f0/0x2070 [ 163.253256] ? try_to_wake_up+0xf9/0x1600 [ 163.257374] ? find_held_lock+0x39/0x1d0 [ 163.261404] ? lock_downgrade+0x990/0x990 [ 163.265519] ? complete+0x18/0x80 [ 163.268942] ? __schedule+0x2070/0x2070 [ 163.272885] ? _raw_spin_unlock_irqrestore+0x31/0xba [ 163.277955] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 163.282936] ? trace_hardirqs_on+0xd/0x10 [ 163.287052] ? __kthread_parkme+0x173/0x240 [ 163.291348] kthread+0x39c/0x470 [ 163.294684] ? process_one_work+0x1be0/0x1be0 [ 163.299148] ? kthread_create_on_node+0x100/0x100 [ 163.303969] ret_from_fork+0x2a/0x40