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 '10.128.10.24' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 24.725197] [ 24.726843] ============================================ [ 24.732257] WARNING: possible recursive locking detected [ 24.737673] 4.16.0-rc6+ #1 Not tainted [ 24.741523] -------------------------------------------- [ 24.746948] vhost-4196/4197 is trying to acquire lock: [ 24.752187] (&vq->mutex){+.+.}, at: [<000000008bae2131>] handle_rx+0xeb1/0x19c0 [ 24.759695] [ 24.759695] but task is already holding lock: [ 24.765629] (&vq->mutex){+.+.}, at: [<00000000c42a0c7e>] handle_rx+0x1f5/0x19c0 [ 24.773133] [ 24.773133] other info that might help us debug this: [ 24.780033] Possible unsafe locking scenario: [ 24.780033] [ 24.786064] CPU0 [ 24.788613] ---- [ 24.791159] lock(&vq->mutex); [ 24.794403] lock(&vq->mutex); [ 24.797649] [ 24.797649] *** DEADLOCK *** [ 24.797649] [ 24.803674] May be due to missing lock nesting notation [ 24.803674] [ 24.810566] 1 lock held by vhost-4196/4197: [ 24.814849] #0: (&vq->mutex){+.+.}, at: [<00000000c42a0c7e>] handle_rx+0x1f5/0x19c0 [ 24.822789] [ 24.822789] stack backtrace: [ 24.827254] CPU: 1 PID: 4197 Comm: vhost-4196 Not tainted 4.16.0-rc6+ #1 [ 24.834062] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 24.843394] Call Trace: [ 24.845963] dump_stack+0x194/0x24d [ 24.849560] ? arch_local_irq_restore+0x53/0x53 [ 24.854216] __lock_acquire+0xe8f/0x3e00 [ 24.858260] ? debug_check_no_locks_freed+0x3c0/0x3c0 [ 24.863417] ? check_usage+0x22f/0xb60 [ 24.867274] ? update_curr+0x415/0x9a0 [ 24.871128] ? update_cfs_rq_load_avg.part.68+0x2d0/0x2d0 [ 24.876632] ? find_held_lock+0x1b0/0x1d0 [ 24.880746] ? check_usage_forwards+0x410/0x410 [ 24.885384] ? check_usage+0x22f/0xb60 [ 24.889245] ? lockdep_on+0x50/0x50 [ 24.892846] ? save_trace+0x2b0/0x2b0 [ 24.896616] ? check_usage_forwards+0x410/0x410 [ 24.901255] ? __bfs+0xa8/0x830 [ 24.904502] ? print_irqtrace_events+0x270/0x270 [ 24.909224] ? lockdep_on+0x50/0x50 [ 24.912817] ? __lock_acquire+0x664/0x3e00 [ 24.917018] ? save_trace+0x2b0/0x2b0 [ 24.920786] ? trace_hardirqs_off+0x10/0x10 [ 24.925073] ? __lock_acquire+0x2d15/0x3e00 [ 24.929366] lock_acquire+0x1d5/0x580 [ 24.933138] ? lock_acquire+0x1d5/0x580 [ 24.937083] ? handle_rx+0xeb1/0x19c0 [ 24.940858] ? lock_release+0xa40/0xa40 [ 24.944799] ? check_same_owner+0x320/0x320 [ 24.949088] ? rcu_note_context_switch+0x710/0x710 [ 24.953990] ? __might_sleep+0x95/0x190 [ 24.957934] ? handle_rx+0xeb1/0x19c0 [ 24.961705] __mutex_lock+0x16f/0x1a80 [ 24.965567] ? handle_rx+0xeb1/0x19c0 [ 24.969333] ? handle_rx+0xeb1/0x19c0 [ 24.973102] ? trace_hardirqs_off+0x10/0x10 [ 24.977388] ? mutex_lock_io_nested+0x1900/0x1900 [ 24.982198] ? trace_hardirqs_off+0x10/0x10 [ 24.986489] ? trace_hardirqs_off+0x10/0x10 [ 24.990776] ? trace_hardirqs_off+0x10/0x10 [ 24.995066] ? trace_hardirqs_off+0x10/0x10 [ 24.999361] ? print_irqtrace_events+0x270/0x270 [ 25.004084] ? remove_wait_queue+0x1b4/0x350 [ 25.008461] ? lock_downgrade+0x980/0x980 [ 25.012581] ? print_irqtrace_events+0x270/0x270 [ 25.017309] ? peek_head_len.part.15+0xdf/0x110 [ 25.021947] ? lock_downgrade+0x980/0x980 [ 25.026061] ? lock_release+0xa40/0xa40 [ 25.030004] ? mark_held_locks+0xaf/0x100 [ 25.034130] ? _raw_spin_unlock_irqrestore+0x31/0xc0 [ 25.039200] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 25.044181] ? trace_hardirqs_on+0xd/0x10 [ 25.048300] mutex_lock_nested+0x16/0x20 [ 25.052329] ? mutex_lock_nested+0x16/0x20 [ 25.056534] handle_rx+0xeb1/0x19c0 [ 25.060134] ? vhost_net_release+0x190/0x190 [ 25.064513] ? __sched_text_start+0x8/0x8 [ 25.068641] ? trace_hardirqs_off+0x10/0x10 [ 25.072930] ? rcu_sync_exit+0xeb/0x130 [ 25.076872] ? lock_downgrade+0x980/0x980 [ 25.080994] ? complete+0x62/0x80 [ 25.084414] ? schedule+0xf5/0x430 [ 25.087926] ? __schedule+0x1ec0/0x1ec0 [ 25.091867] ? do_raw_spin_trylock+0x190/0x190 [ 25.096416] ? trace_hardirqs_on+0xd/0x10 [ 25.100532] ? vhost_worker+0x1f0/0x470 [ 25.104474] handle_rx_net+0x19/0x20 [ 25.108155] vhost_worker+0x268/0x470 [ 25.111923] ? lockdep_init_map+0x9/0x10 [ 25.115952] ? vhost_flush_work+0x20/0x20 [ 25.120074] ? trace_hardirqs_on_caller+0x421/0x5c0 executing program executing program [ 25.125085] ? trace_hardirqs_on+0xd/0x10 [ 25.129216] ? __kthread_parkme+0x176/0x240 [ 25.133508] kthread+0x33c/0x400 [ 25.136843] ? vhost_flush_work+0x20/0x20 [ 25.140957] ? kthread_stop+0x7a0/0x7a0 [ 25.144901] ret_from_fork+0x3a/0x50 executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program 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