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-mmots-kasan-gce-7,10.128.15.207' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 31.353741] [ 31.354128] ============================================ [ 31.354872] WARNING: possible recursive locking detected [ 31.355603] 4.13.0-mm1+ #7 Not tainted [ 31.356122] -------------------------------------------- [ 31.356839] syzkaller025015/2982 is trying to acquire lock: [ 31.357600] (&grp->list_mutex){++++}, at: [] snd_seq_deliver_event+0x279/0x790 [ 31.358785] [ 31.358785] but task is already holding lock: [ 31.359580] (&grp->list_mutex){++++}, at: [] snd_seq_deliver_event+0x279/0x790 [ 31.360758] [ 31.360758] other info that might help us debug this: [ 31.361647] Possible unsafe locking scenario: [ 31.361647] [ 31.362442] CPU0 [ 31.362791] ---- [ 31.363139] lock(&grp->list_mutex); [ 31.363645] lock(&grp->list_mutex); [ 31.364192] [ 31.364192] *** DEADLOCK *** [ 31.364192] [ 31.365003] May be due to missing lock nesting notation [ 31.365003] [ 31.365910] 2 locks held by syzkaller025015/2982: [ 31.366549] #0: (register_mutex#4){+.+.}, at: [] odev_release+0x4a/0x70 [ 31.367666] #1: (&grp->list_mutex){++++}, at: [] snd_seq_deliver_event+0x279/0x790 [ 31.368900] [ 31.368900] stack backtrace: [ 31.369498] CPU: 1 PID: 2982 Comm: syzkaller025015 Not tainted 4.13.0-mm1+ #7 [ 31.370449] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 31.371677] Call Trace: [ 31.372057] dump_stack+0x194/0x257 [ 31.372544] ? arch_local_irq_restore+0x53/0x53 [ 31.373169] __lock_acquire+0x1232/0x4620 [ 31.373725] ? debug_check_no_locks_freed+0x3d0/0x3d0 [ 31.374412] ? debug_check_no_locks_freed+0x3d0/0x3d0 [ 31.379563] ? snd_seq_deliver_event+0x318/0x790 [ 31.384283] ? save_stack_trace+0x16/0x20 [ 31.388397] ? __lock_acquire+0x20fd/0x4620 [ 31.392684] ? unwind_get_return_address+0x61/0xa0 [ 31.397577] ? __save_stack_trace+0x61/0xd0 [ 31.401868] ? debug_check_no_locks_freed+0x3d0/0x3d0 [ 31.407024] ? __lock_acquire+0x732/0x4620 [ 31.411224] ? snd_seq_deliver_event+0x12c/0x790 [ 31.415944] ? save_stack_trace+0x16/0x20 [ 31.420056] ? debug_check_no_locks_freed+0x3d0/0x3d0 [ 31.425214] ? check_noncircular+0x20/0x20 [ 31.429414] ? debug_check_no_locks_freed+0x3d0/0x3d0 [ 31.434570] ? debug_check_no_locks_freed+0x3d0/0x3d0 [ 31.439725] ? check_noncircular+0x20/0x20 [ 31.443925] ? save_stack_trace+0x16/0x20 [ 31.448038] ? __lock_acquire+0x20fd/0x4620 [ 31.452324] ? find_held_lock+0x39/0x1d0 [ 31.456351] lock_acquire+0x1d5/0x580 [ 31.460115] ? snd_seq_deliver_event+0x279/0x790 [ 31.464835] ? lock_release+0xd70/0xd70 [ 31.468773] ? check_same_owner+0x320/0x320 [ 31.473061] ? lock_release+0xd70/0xd70 [ 31.477001] ? __might_sleep+0x95/0x190 [ 31.480942] down_read+0x96/0x150 [ 31.484357] ? snd_seq_deliver_event+0x279/0x790 [ 31.489086] ? __down_interruptible+0x6a0/0x6a0 [ 31.493719] ? _raw_read_unlock+0x22/0x30 [ 31.497830] ? snd_seq_port_use_ptr+0x12d/0x1c0 [ 31.502461] snd_seq_deliver_event+0x279/0x790 [ 31.507009] ? do_raw_spin_trylock+0x190/0x190 [ 31.511555] ? snd_seq_deliver_single_event.constprop.11+0x940/0x940 [ 31.518020] ? _raw_spin_unlock_irqrestore+0x31/0xba [ 31.523087] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 31.528065] ? snd_seq_client_use_ptr+0x85/0x330 [ 31.532783] snd_seq_kernel_client_dispatch+0x11e/0x150 [ 31.538121] dummy_input+0x2c4/0x400 [ 31.541800] ? dummy_free+0x20/0x20 [ 31.545392] ? snd_seq_port_use_ptr+0x12d/0x1c0 [ 31.550026] ? dummy_free+0x20/0x20 [ 31.553617] snd_seq_deliver_single_event.constprop.11+0x2fb/0x940 [ 31.559907] ? snd_seq_ioctl_running_mode+0x150/0x150 [ 31.565063] ? queueptr+0x88/0xa0 [ 31.568482] ? update_timestamp_of_queue+0x14d/0x200 [ 31.573551] snd_seq_deliver_event+0x318/0x790 [ 31.578100] ? snd_seq_deliver_single_event.constprop.11+0x940/0x940 [ 31.584560] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 31.589540] ? snd_seq_client_use_ptr+0x85/0x330 [ 31.594260] snd_seq_kernel_client_dispatch+0x11e/0x150 [ 31.599588] dummy_input+0x2c4/0x400 [ 31.603265] ? dummy_free+0x20/0x20 [ 31.606858] ? snd_seq_port_use_ptr+0x12d/0x1c0 [ 31.611491] ? dummy_free+0x20/0x20 [ 31.615082] snd_seq_deliver_single_event.constprop.11+0x2fb/0x940 [ 31.621377] ? snd_seq_ioctl_running_mode+0x150/0x150 [ 31.626533] ? snd_seq_client_use_ptr+0x3c/0x330 [ 31.631253] snd_seq_deliver_event+0x12c/0x790 [ 31.635799] ? do_raw_spin_trylock+0x190/0x190 [ 31.640346] ? snd_seq_deliver_single_event.constprop.11+0x940/0x940 [ 31.646806] ? _raw_spin_unlock_irqrestore+0x31/0xba [ 31.651876] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 31.656864] ? trace_hardirqs_on+0xd/0x10 [ 31.660989] ? snd_seq_client_use_ptr+0x85/0x330 [ 31.665713] snd_seq_kernel_client_dispatch+0x11e/0x150 [ 31.671041] snd_seq_oss_midi_reset+0x44b/0x700 [ 31.675673] ? snd_seq_oss_midi_filemode+0xf0/0xf0 [ 31.680568] ? depot_save_stack+0x12c/0x490 [ 31.684855] snd_seq_oss_synth_reset+0x398/0x980 [ 31.689577] ? locks_remove_file+0x3fa/0x5a0 [ 31.693960] ? snd_seq_oss_synth_cleanup+0x400/0x400 [ 31.699028] ? __fsnotify_parent+0xb4/0x3a0 [ 31.703317] snd_seq_oss_reset+0x6c/0x260 [ 31.707427] ? free_info_entries+0x36/0x36 [ 31.711625] snd_seq_oss_release+0x71/0x120 [ 31.715910] odev_release+0x52/0x70 [ 31.719511] __fput+0x333/0x7f0 [ 31.722755] ? fput+0x140/0x140 [ 31.726001] ? _raw_spin_unlock_irq+0x27/0x70 [ 31.730469] ____fput+0x15/0x20 [ 31.733724] task_work_run+0x199/0x270 [ 31.737586] ? task_work_cancel+0x210/0x210 [ 31.741871] ? _raw_spin_unlock+0x22/0x30 [ 31.745985] ? switch_task_namespaces+0x87/0xc0 [ 31.750629] do_exit+0xa52/0x1b40 [ 31.754061] ? unwind_dump+0x4c0/0x4c0 [ 31.757923] ? mm_update_next_owner+0x930/0x930 [ 31.762575] ? __kernel_text_address+0xae/0xe0 [ 31.767134] ? unwind_get_return_address+0x61/0xa0 [ 31.772031] ? __save_stack_trace+0x7e/0xd0 [ 31.776319] ? depot_save_stack+0x12c/0x490 [ 31.780605] ? putname+0xee/0x130 [ 31.784024] ? save_stack+0xa3/0xd0 [ 31.787615] ? save_stack_trace+0x16/0x20 [ 31.791726] ? save_stack+0x43/0xd0 [ 31.795317] ? kasan_slab_free+0x71/0xc0 [ 31.799341] ? kmem_cache_free+0x77/0x280 [ 31.803455] ? putname+0xee/0x130 [ 31.806876] ? do_sys_open+0x31b/0x6d0 [ 31.810727] ? SyS_openat+0x30/0x40 [ 31.814322] ? entry_SYSCALL_64_fastpath+0x1f/0xbe [ 31.819220] ? __lock_is_held+0xbc/0x140 [ 31.823250] ? __fd_install+0x2f7/0x6a0 [ 31.827188] ? get_unused_fd_flags+0x190/0x190 [ 31.831737] ? rcu_pm_notify+0xc0/0xc0 [ 31.835588] ? putname+0xee/0x130 [ 31.839005] ? rcu_read_lock_sched_held+0x108/0x120 [ 31.843985] ? kmem_cache_free+0x249/0x280 [ 31.848192] ? putname+0xf3/0x130 [ 31.851610] do_group_exit+0x149/0x400 [ 31.855463] ? filp_open+0x70/0x70 [ 31.858966] ? SyS_exit+0x30/0x30 [ 31.862386] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 31.867366] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 31.872083] SyS_exit_group+0x1d/0x20 [ 31.875847] entry_SYSCALL_64_fastpath+0x1f/0xbe [ 31.880566] RIP: 0033:0x442c58 [ 31.883720] RSP: 002b:00007fff759563f8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 31.891392] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000442c58 [ 31.898627] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [