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-6,10.128.0.6' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 39.806862] [ 39.808531] ====================================================== [ 39.814813] WARNING: possible circular locking dependency detected [ 39.821093] 4.13.0-mm1+ #7 Not tainted [ 39.824941] ------------------------------------------------------ [ 39.831225] loop0/2988 is trying to acquire lock: [ 39.836029] (&sb->s_type->i_mutex_key#9){++++}, at: [] generic_file_write_iter+0xdc/0x7a0 [ 39.845973] [ 39.845973] but now in release context of a crosslock acquired at the following: [ 39.854946] ((complete)&ret.event){+.+.}, at: [] submit_bio_wait+0x15e/0x200 [ 39.863754] [ 39.863754] which lock already depends on the new lock. [ 39.863754] [ 39.872033] [ 39.872033] the existing dependency chain (in reverse order) is: [ 39.879617] [ 39.879617] -> #4 ((complete)&ret.event){+.+.}: [ 39.886608] __lock_acquire+0x328f/0x4620 [ 39.891241] lock_acquire+0x1d5/0x580 [ 39.895525] wait_for_completion_io+0xc8/0x770 [ 39.900595] submit_bio_wait+0x15e/0x200 [ 39.905142] blkdev_issue_zeroout+0x13c/0x1d0 [ 39.910123] ext4_init_inode_table+0x4fd/0xdb1 [ 39.915189] ext4_lazyinit_thread+0x81a/0xd40 [ 39.920170] kthread+0x39c/0x470 [ 39.924022] ret_from_fork+0x2a/0x40 [ 39.928217] [ 39.928217] -> #3 (&meta_group_info[i]->alloc_sem){++++}: [ 39.935200] __lock_acquire+0x328f/0x4620 [ 39.939831] lock_acquire+0x1d5/0x580 [ 39.944114] down_read+0x96/0x150 [ 39.948051] __ext4_new_inode+0x26dc/0x4f00 [ 39.952857] ext4_symlink+0x2d9/0xae0 [ 39.957140] vfs_symlink+0x323/0x560 [ 39.961336] SyS_symlink+0x134/0x200 [ 39.965534] entry_SYSCALL_64_fastpath+0x1f/0xbe [ 39.970770] [ 39.970770] -> #2 (jbd2_handle){.+.+}: [ 39.976102] __lock_acquire+0x328f/0x4620 [ 39.980732] lock_acquire+0x1d5/0x580 [ 39.985019] start_this_handle+0x4b8/0x1080 [ 39.989824] jbd2__journal_start+0x389/0x9f0 [ 39.994716] __ext4_journal_start_sb+0x15f/0x550 [ 39.999955] ext4_dirty_inode+0x56/0xa0 [ 40.004413] __mark_inode_dirty+0x912/0x1170 [ 40.009305] generic_update_time+0x1b2/0x270 [ 40.014196] touch_atime+0x26d/0x2f0 [ 40.018395] ext4_file_mmap+0x161/0x1b0 [ 40.022854] mmap_region+0xa99/0x15a0 [ 40.027138] do_mmap+0x6a1/0xd50 [ 40.030990] vm_mmap_pgoff+0x1de/0x280 [ 40.035359] SyS_mmap_pgoff+0x462/0x5f0 [ 40.039821] SyS_mmap+0x16/0x20 [ 40.043588] entry_SYSCALL_64_fastpath+0x1f/0xbe [ 40.048827] [ 40.048827] -> #1 (&mm->mmap_sem){++++}: [ 40.054335] __lock_acquire+0x328f/0x4620 [ 40.058967] lock_acquire+0x1d5/0x580 [ 40.063254] __might_fault+0x13a/0x1d0 [ 40.067627] _copy_to_user+0x2c/0xc0 [ 40.071825] filldir+0x1a7/0x320 [ 40.075679] dcache_readdir+0x12d/0x5e0 [ 40.080139] iterate_dir+0x4b2/0x5d0 [ 40.084338] SyS_getdents+0x225/0x450 [ 40.088625] entry_SYSCALL_64_fastpath+0x1f/0xbe [ 40.093865] [ 40.093865] -> #0 (&sb->s_type->i_mutex_key#9){++++}: [ 40.100503] down_write+0x87/0x120 [ 40.104531] generic_file_write_iter+0xdc/0x7a0 [ 40.109685] do_iter_readv_writev+0x531/0x7f0 [ 40.114666] do_iter_write+0x15a/0x540 [ 40.119039] vfs_iter_write+0x77/0xb0 [ 40.123321] [ 40.123321] other info that might help us debug this: [ 40.123321] [ 40.131425] Chain exists of: [ 40.131425] &sb->s_type->i_mutex_key#9 --> &meta_group_info[i]->alloc_sem --> (complete)&ret.event [ 40.131425] [ 40.145006] Possible unsafe locking scenario by crosslock: [ 40.145006] [ 40.152155] CPU0 CPU1 [ 40.156786] ---- ---- [ 40.161415] lock(&meta_group_info[i]->alloc_sem); [ 40.166395] lock((complete)&ret.event); [ 40.170505] lock(&sb->s_type->i_mutex_key#9); [ 40.177654] unlock((complete)&ret.event); [ 40.184455] [ 40.184455] *** DEADLOCK *** [ 40.184455] [ 40.190478] 1 lock held by loop0/2988: [ 40.194327] #0: (&x->wait#14){..-.}, at: [] complete+0x18/0x80 [ 40.202015] [ 40.202015] stack backtrace: [ 40.206477] CPU: 1 PID: 2988 Comm: loop0 Not tainted 4.13.0-mm1+ #7 [ 40.212845] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 40.222164] Call Trace: [ 40.224723] dump_stack+0x194/0x257 [ 40.228314] ? arch_local_irq_restore+0x53/0x53 [ 40.232952] print_circular_bug+0x503/0x710 [ 40.237239] ? print_circular_bug_entry+0xb0/0xb0 [ 40.242046] ? debug_check_no_locks_freed+0x3d0/0x3d0 [ 40.247211] check_prev_add+0x865/0x1520 [ 40.251237] ? shmem_unused_huge_scan+0x160/0x160 [ 40.256044] ? graph_lock+0x170/0x170 [ 40.259809] ? check_usage+0xb70/0xb70 [ 40.263664] ? memcpy+0x45/0x50 [ 40.266907] ? iov_iter_advance+0x2a1/0x13f0 [ 40.271279] ? hlock_class+0x140/0x140 [ 40.275131] lock_commit_crosslock+0xe73/0x1d10 [ 40.279763] ? lock_commit_crosslock+0xe73/0x1d10 [ 40.284574] ? check_prev_add+0x1520/0x1520 [ 40.288861] ? lock_acquire+0x1d5/0x580 [ 40.292796] ? complete+0x18/0x80 [ 40.296212] ? lock_release+0xd70/0xd70 [ 40.300149] ? find_held_lock+0x39/0x1d0 [ 40.304178] complete+0x24/0x80 [ 40.307423] submit_bio_wait_endio+0x9c/0xd0 [ 40.311795] ? bio_iov_iter_get_pages+0x4e0/0x4e0 [ 40.316606] bio_endio+0x2f8/0x8d0 [ 40.320109] ? bio_dirty_fn+0x3e0/0x3e0 [ 40.324050] ? rcu_pm_notify+0xc0/0xc0 [ 40.327905] ? bio_advance+0xf8/0x370 [ 40.331672] blk_update_request+0x2a6/0xe20 [ 40.335959] ? blk_account_io_completion+0x410/0x410 [ 40.341028] blk_mq_end_request+0x54/0x120 [ 40.345228] lo_complete_rq+0xbe/0x1f0 [ 40.349082] __blk_mq_complete_request+0x38f/0x6c0 [ 40.353976] blk_mq_complete_request+0x4f/0x60 [ 40.358521] loop_queue_work+0x26b/0x3900 [ 40.362635] ? do_raw_spin_trylock+0x190/0x190 [ 40.367185] ? lo_rw_aio+0x1e70/0x1e70 [ 40.371037] ? _raw_spin_unlock_irq+0x27/0x70 [ 40.375498] ? finish_task_switch+0x1d3/0x740 [ 40.379955] ? finish_task_switch+0x1aa/0x740 [ 40.384414] ? preempt_notifier_dec+0x20/0x20 [ 40.388873] ? check_noncircular+0x20/0x20 [ 40.393071] ? __schedule+0x8f0/0x2070 [ 40.396927] ? do_raw_spin_trylock+0x190/0x190 [ 40.401477] ? lock_release+0xd70/0xd70 [ 40.405415] ? compat_start_thread+0x80/0x80 [ 40.409788] ? find_held_lock+0x39/0x1d0 [ 40.413834] ? finish_task_switch+0x1aa/0x740 [ 40.418306] ? kthread_worker_fn+0x4ad/0x9b0 [ 40.422682] ? do_raw_spin_trylock+0x190/0x190 [ 40.427229] ? check_same_owner+0x320/0x320 [ 40.431515] ? _raw_spin_unlock_irq+0x27/0x70 [ 40.435974] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 40.440955] kthread_worker_fn+0x340/0x9b0 [ 40.445156] ? kthread_flush_work+0x560/0x560 [ 40.449617] ? lock_downgrade+0x990/0x990 [ 40.453730] ? complete+0x18/0x80 [ 40.457146] ? schedule+0x