[   22.625601] audit: type=1800 audit(1542442812.230:21): pid=5751 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="bootlogs" dev="sda1" ino=2419 res=0
[   22.645175] audit: type=1800 audit(1542442812.230:22): pid=5751 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="motd" dev="sda1" ino=2447 res=0
[   22.671591] audit: type=1800 audit(1542442812.240:23): pid=5751 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="rsyslog" dev="sda1" ino=2442 res=0
[....] 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

syzkaller login: [   30.032885] sshd (5890) used greatest stack depth: 15744 bytes left
Warning: Permanently added '10.128.0.112' (ECDSA) to the list of known hosts.
executing program
[   36.501589] 
[   36.503896] ======================================================
[   36.510191] WARNING: possible circular locking dependency detected
[   36.516492] 4.20.0-rc2+ #338 Not tainted
[   36.520528] ------------------------------------------------------
[   36.526817] kworker/0:2/3421 is trying to acquire lock:
[   36.532161] 00000000c364a3bd (&mdev->req_queue_mutex){+.+.}, at: v4l2_release+0x1d7/0x3a0
[   36.540994] 
[   36.540994] but task is already holding lock:
[   36.547074] 000000009258f90c ((delayed_fput_work).work){+.+.}, at: process_one_work+0xb9a/0x1c40
[   36.556163] 
[   36.556163] which lock already depends on the new lock.
[   36.556163] 
[   36.564573] 
[   36.564573] the existing dependency chain (in reverse order) is:
[   36.572295] 
[   36.572295] -> #3 ((delayed_fput_work).work){+.+.}:
[   36.578952]        process_one_work+0xc0a/0x1c40
[   36.583684]        worker_thread+0x17f/0x1390
[   36.588154]        kthread+0x35a/0x440
[   36.592022]        ret_from_fork+0x3a/0x50
[   36.596228] 
[   36.596228] -> #2 ((wq_completion)"events"){+.+.}:
[   36.602772]        flush_workqueue+0x30a/0x1e10
[   36.607424]        vim2m_stop_streaming+0x7c/0x2c0
[   36.612329]        __vb2_queue_cancel+0x171/0xd20
[   36.617307]        vb2_core_queue_release+0x26/0x80
[   36.622302]        vb2_queue_release+0x15/0x20
[   36.627044]        v4l2_m2m_ctx_release+0x1e/0x35
[   36.631872]        vim2m_release+0xe6/0x150
[   36.636300]        v4l2_release+0x224/0x3a0
[   36.640607]        __fput+0x385/0xa30
[   36.644391]        ____fput+0x15/0x20
[   36.648224]        task_work_run+0x1e8/0x2a0
[   36.652741]        exit_to_usermode_loop+0x318/0x380
[   36.657824]        do_syscall_64+0x6be/0x820
[   36.662209]        entry_SYSCALL_64_after_hwframe+0x49/0xbe
[   36.667893] 
[   36.667893] -> #1 (&dev->dev_mutex){+.+.}:
[   36.673720]        __mutex_lock+0x166/0x16f0
[   36.678246]        mutex_lock_nested+0x16/0x20
[   36.682836]        vim2m_release+0xbc/0x150
[   36.687148]        v4l2_release+0x224/0x3a0
[   36.691468]        __fput+0x385/0xa30
[   36.695377]        ____fput+0x15/0x20
[   36.699163]        task_work_run+0x1e8/0x2a0
[   36.703564]        exit_to_usermode_loop+0x318/0x380
[   36.708646]        do_syscall_64+0x6be/0x820
[   36.713031]        entry_SYSCALL_64_after_hwframe+0x49/0xbe
[   36.718714] 
[   36.718714] -> #0 (&mdev->req_queue_mutex){+.+.}:
[   36.725019]        lock_acquire+0x1ed/0x520
[   36.729464]        __mutex_lock+0x166/0x16f0
[   36.733851]        mutex_lock_nested+0x16/0x20
[   36.738465]        v4l2_release+0x1d7/0x3a0
[   36.742784]        __fput+0x385/0xa30
[   36.746561]        delayed_fput+0x55/0x80
[   36.750684]        process_one_work+0xc90/0x1c40
[   36.755421]        worker_thread+0x17f/0x1390
[   36.759896]        kthread+0x35a/0x440
[   36.763758]        ret_from_fork+0x3a/0x50
[   36.767964] 
[   36.767964] other info that might help us debug this:
[   36.767964] 
[   36.776229] Chain exists of:
[   36.776229]   &mdev->req_queue_mutex --> (wq_completion)"events" --> (delayed_fput_work).work
[   36.776229] 
[   36.789372]  Possible unsafe locking scenario:
[   36.789372] 
[   36.795411]        CPU0                    CPU1
[   36.800316]        ----                    ----
[   36.805127]   lock((delayed_fput_work).work);
[   36.809606]                                lock((wq_completion)"events");
[   36.816508]                                lock((delayed_fput_work).work);
[   36.823612]   lock(&mdev->req_queue_mutex);
[   36.828077] 
[   36.828077]  *** DEADLOCK ***
[   36.828077] 
[   36.834123] 2 locks held by kworker/0:2/3421:
[   36.838589]  #0: 00000000312444b2 ((wq_completion)"events"){+.+.}, at: process_one_work+0xb43/0x1c40
[   36.847850]  #1: 000000009258f90c ((delayed_fput_work).work){+.+.}, at: process_one_work+0xb9a/0x1c40
[   36.851572] kobject: 'regulatory.0' (0000000078fe9404): kobject_uevent_env
[   36.857201] 
[   36.857201] stack backtrace:
[   36.857214] CPU: 0 PID: 3421 Comm: kworker/0:2 Not tainted 4.20.0-rc2+ #338
[   36.857223] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
[   36.864295] kobject: 'regulatory.0' (0000000078fe9404): fill_kobj_path: path = '/devices/platform/regulatory.0'
[   36.868710] Workqueue: events delayed_fput
[   36.899692] Call Trace:
[   36.902280]  dump_stack+0x244/0x39d
[   36.905892]  ? dump_stack_print_info.cold.1+0x20/0x20
[   36.911064]  ? vprintk_func+0x85/0x181
[   36.914934]  print_circular_bug.isra.35.cold.54+0x1bd/0x27d
[   36.920746]  ? save_trace+0xe0/0x290
[   36.924438]  __lock_acquire+0x3399/0x4c20
[   36.928571]  ? mark_held_locks+0x130/0x130
[   36.932783]  ? __update_load_avg_blocked_se+0x690/0x690
[   36.938241]  ? __update_load_avg_se+0xae0/0xae0
[   36.942888]  ? print_usage_bug+0xc0/0xc0
[   36.946926]  ? lock_unpin_lock+0x4a0/0x4a0
[   36.951136]  ? update_load_avg+0x387/0x2470
[   36.955431]  ? find_held_lock+0x36/0x1c0
[   36.959636]  ? zap_class+0x640/0x640
[   36.963383]  ? __lock_acquire+0x62f/0x4c20
[   36.967799]  ? zap_class+0x640/0x640
[   36.971506]  ? mark_held_locks+0x130/0x130
[   36.975726]  ? add_timer+0x629/0x15a0
[   36.979537]  lock_acquire+0x1ed/0x520
[   36.983316]  ? v4l2_release+0x1d7/0x3a0
[   36.987409]  ? lock_release+0xa00/0xa00
[   36.991496]  ? perf_trace_sched_process_exec+0x860/0x860
[   36.997019]  ? print_usage_bug+0xc0/0xc0
[   37.001059]  ? v4l2_release+0x1d7/0x3a0
[   37.005009]  __mutex_lock+0x166/0x16f0
[   37.008869]  ? v4l2_release+0x1d7/0x3a0
[   37.012944]  ? v4l2_release+0x1d7/0x3a0
[   37.016902]  ? mutex_trylock+0x2b0/0x2b0
[   37.020940]  ? __lock_acquire+0x62f/0x4c20
[   37.025214]  ? mark_held_locks+0x130/0x130
[   37.029435]  ? mark_held_locks+0x130/0x130
[   37.033651]  ? mark_held_locks+0x130/0x130
[   37.037986]  ? lock_downgrade+0x900/0x900
[   37.042119]  ? check_preemption_disabled+0x48/0x280
[   37.047119]  ? zap_class+0x640/0x640
[   37.050815]  ? trace_event_raw_event_lock+0x340/0x340
[   37.056122]  ? zap_class+0x640/0x640
[   37.059815]  ? zap_class+0x640/0x640
[   37.063506]  ? __sanitizer_cov_trace_const_cmp4+0x16/0x20
[   37.069017]  ? fsnotify+0x50e/0xef0
[   37.072621]  ? __lock_is_held+0xb5/0x140
[   37.076664]  ? __sanitizer_cov_trace_const_cmp8+0x18/0x20
[   37.082183]  ? locks_remove_file+0x3c6/0x5c0
[   37.086821]  ? __sanitizer_cov_trace_const_cmp2+0x18/0x20
[   37.092455]  ? ima_file_free+0x132/0x650
[   37.096494]  ? fsnotify_first_mark+0x350/0x350
[   37.101181]  ? ima_file_check+0x130/0x130
[   37.105315]  ? vivid_remove+0x460/0x460
[   37.109275]  mutex_lock_nested+0x16/0x20
[   37.113313]  ? mutex_lock_nested+0x16/0x20
[   37.117528]  v4l2_release+0x1d7/0x3a0
[   37.121621]  ? dev_debug_store+0x140/0x140
[   37.125836]  __fput+0x385/0xa30
[   37.129097]  ? get_max_files+0x20/0x20
[   37.133181]  delayed_fput+0x55/0x80
[   37.136794]  process_one_work+0xc90/0x1c40
[   37.141004]  ? mark_held_locks+0x130/0x130
[   37.145218]  ? pwq_dec_nr_in_flight+0x4a0/0x4a0
[   37.150093]  ? __switch_to_asm+0x40/0x70
[   37.154433]  ? __switch_to_asm+0x34/0x70
[   37.158611]  ? __switch_to_asm+0x34/0x70
[   37.162649]  ? __switch_to_asm+0x40/0x70
[   37.166809]  ? __switch_to_asm+0x34/0x70
[   37.170850]  ? __switch_to_asm+0x40/0x70
[   37.174884]  ? __switch_to_asm+0x34/0x70
[   37.178929]  ? __switch_to_asm+0x40/0x70
[   37.182975]  ? __schedule+0x8d7/0x21d0
[   37.186842]  ? lock_downgrade+0x900/0x900
[   37.190966]  ? zap_class+0x640/0x640
[   37.194785]  ? find_held_lock+0x36/0x1c0
[   37.198934]  ? lock_acquire+0x1ed/0x520
[   37.202895]  ? worker_thread+0x3e0/0x1390
[   37.207029]  ? kasan_check_read+0x11/0x20
[   37.211543]  ? do_raw_spin_lock+0x14f/0x350
[   37.215854]  ? kasan_check_read+0x11/0x20
[   37.219982]  ? rwlock_bug.part.2+0x90/0x90
[   37.224192]  ? trace_hardirqs_on+0x310/0x310
[   37.228700]  worker_thread+0x17f/0x1390
[   37.232890]  ? __switch_to_asm+0x34/0x70
[   37.236939]  ? process_one_work+0x1c40/0x1c40
[   37.241413]  ? __sched_text_start+0x8/0x8
[   37.245816]  ? __kthread_parkme+0xce/0x1a0
[   37.250030]  ? _raw_spin_unlock_irqrestore+0x82/0xd0
[   37.255109]  ? _raw_spin_unlock_irqrestore+0x82/0xd0
[   37.260187]  ? lockdep_hardirqs_on+0x3bb/0x5b0
[   37.264877]  ? trace_hardirqs_on+0xbd/0x310
[   37.269190]  ? kasan_check_read+0x11/0x20
[   37.273318]  ? __kthread_parkme+0xce/0x1a0
[   37.277534]  ? trace_hardirqs_off_caller+0x310/0x310
[   37.282788]  ? _raw_spin_unlock_irqrestore+0x6d/0xd0
[   37.287869]  ? __sanitizer_cov_trace_const_cmp8+0x18/0x20
[   37.293382]  ? __kthread_parkme+0xfb/0x1a0
[   37.297592]  ? process_one_work+0x1c40/0x1c40
[   37.302062]  kthread+0x35a/0x440
executing program
[   37.305409]  ? kthread_stop+0x900/0x900
[   37.309642]  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
executing program
executing program
executing program
executing program
executing program
executing program
executing program
executing program
[   40.051561] kobject: 'regulatory.0' (0000000078fe9404): kobject_uevent_env
[   40.058862] kobject: 'regulatory.0' (0000000078fe9404): fill_kobj_path: path = '/devices/platform/regulatory.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