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-8,10.128.0.3' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 41.216989] [ 41.218650] ====================================================== [ 41.224940] WARNING: possible circular locking dependency detected [ 41.231251] 4.13.0-next-20170904+ #14 Not tainted [ 41.236061] ------------------------------------------------------ [ 41.242348] loop0/2994 is trying to acquire lock: [ 41.247153] (&sb->s_type->i_mutex_key#9){++++}, at: [] generic_file_write_iter+0xdc/0x7a0 [ 41.257108] [ 41.257108] but now in release context of a crosslock acquired at the following: [ 41.266090] ((complete)&ret.event){+.+.}, at: [] submit_bio_wait+0x15e/0x200 [ 41.274919] [ 41.274919] which lock already depends on the new lock. [ 41.274919] [ 41.283207] [ 41.283207] the existing dependency chain (in reverse order) is: [ 41.290798] [ 41.290798] -> #4 ((complete)&ret.event){+.+.}: [ 41.296937] __lock_acquire+0x328f/0x4620 [ 41.301577] lock_acquire+0x1d5/0x580 [ 41.305867] wait_for_completion_io+0xc8/0x770 [ 41.310937] submit_bio_wait+0x15e/0x200 [ 41.315490] blkdev_issue_zeroout+0x13c/0x1d0 [ 41.320476] ext4_init_inode_table+0x4fd/0xdb1 [ 41.325558] ext4_lazyinit_thread+0x81a/0xd40 [ 41.330551] kthread+0x39c/0x470 [ 41.334409] ret_from_fork+0x2a/0x40 [ 41.338618] [ 41.338618] -> #3 (&meta_group_info[i]->alloc_sem){++++}: [ 41.345621] __lock_acquire+0x328f/0x4620 [ 41.350262] lock_acquire+0x1d5/0x580 [ 41.354552] down_read+0x96/0x150 [ 41.358494] __ext4_new_inode+0x26dc/0x4f00 [ 41.363305] ext4_symlink+0x2d9/0xae0 [ 41.367595] vfs_symlink+0x323/0x560 [ 41.371807] SyS_symlink+0x134/0x200 [ 41.376010] entry_SYSCALL_64_fastpath+0x1f/0xbe [ 41.381251] [ 41.381251] -> #2 (jbd2_handle){.+.+}: [ 41.386589] __lock_acquire+0x328f/0x4620 [ 41.391238] lock_acquire+0x1d5/0x580 [ 41.395528] start_this_handle+0x4b8/0x1080 [ 41.400336] jbd2__journal_start+0x389/0x9f0 [ 41.405249] __ext4_journal_start_sb+0x15f/0x550 [ 41.410499] ext4_dirty_inode+0x56/0xa0 [ 41.414961] __mark_inode_dirty+0x912/0x1170 [ 41.419864] generic_update_time+0x1b2/0x270 [ 41.424759] touch_atime+0x26d/0x2f0 [ 41.428966] ext4_file_mmap+0x161/0x1b0 [ 41.433430] mmap_region+0xa99/0x15a0 [ 41.437718] do_mmap+0x6a1/0xd50 [ 41.441575] vm_mmap_pgoff+0x1de/0x280 [ 41.445950] SyS_mmap_pgoff+0x462/0x5f0 [ 41.450416] SyS_mmap+0x16/0x20 [ 41.454186] entry_SYSCALL_64_fastpath+0x1f/0xbe [ 41.459439] [ 41.459439] -> #1 (&mm->mmap_sem){++++}: [ 41.464955] __lock_acquire+0x328f/0x4620 [ 41.469592] lock_acquire+0x1d5/0x580 [ 41.473891] __might_fault+0x13a/0x1d0 [ 41.478268] _copy_to_user+0x2c/0xc0 [ 41.482479] filldir+0x1a7/0x320 [ 41.486335] dcache_readdir+0x12d/0x5e0 [ 41.490809] iterate_dir+0x4b2/0x5d0 [ 41.495023] SyS_getdents+0x225/0x450 [ 41.499316] entry_SYSCALL_64_fastpath+0x1f/0xbe [ 41.504557] [ 41.504557] -> #0 (&sb->s_type->i_mutex_key#9){++++}: [ 41.511213] down_write+0x87/0x120 [ 41.515254] generic_file_write_iter+0xdc/0x7a0 [ 41.520414] do_iter_readv_writev+0x531/0x7f0 [ 41.525401] do_iter_write+0x15a/0x540 [ 41.529778] vfs_iter_write+0x77/0xb0 [ 41.534065] [ 41.534065] other info that might help us debug this: [ 41.534065] [ 41.542180] Chain exists of: [ 41.542180] &sb->s_type->i_mutex_key#9 --> &meta_group_info[i]->alloc_sem --> (complete)&ret.event [ 41.542180] [ 41.555773] Possible unsafe locking scenario by crosslock: [ 41.555773] [ 41.562923] CPU0 CPU1 [ 41.567556] ---- ---- [ 41.572193] lock(&meta_group_info[i]->alloc_sem); [ 41.577180] lock((complete)&ret.event); [ 41.581303] lock(&sb->s_type->i_mutex_key#9); [ 41.588459] unlock((complete)&ret.event); [ 41.595263] [ 41.595263] *** DEADLOCK *** [ 41.595263] [ 41.601288] 1 lock held by loop0/2994: [ 41.605146] #0: (&x->wait#14){..-.}, at: [] complete+0x18/0x80 [ 41.612834] [ 41.612834] stack backtrace: [ 41.617299] CPU: 0 PID: 2994 Comm: loop0 Not tainted 4.13.0-next-20170904+ #14 [ 41.624621] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 41.633943] Call Trace: [ 41.636503] dump_stack+0x194/0x257 [ 41.640104] ? arch_local_irq_restore+0x53/0x53 [ 41.644744] print_circular_bug+0x503/0x710 [ 41.649048] ? print_circular_bug_entry+0xb0/0xb0 [ 41.653858] ? debug_check_no_locks_freed+0x3d0/0x3d0 [ 41.659021] check_prev_add+0x865/0x1520 [ 41.663065] ? shmem_unused_huge_scan+0x160/0x160 [ 41.667874] ? graph_lock+0x170/0x170 [ 41.671648] ? check_usage+0xb70/0xb70 [ 41.675504] ? memcpy+0x45/0x50 [ 41.678753] ? iov_iter_advance+0x2a1/0x13f0 [ 41.683132] ? hlock_class+0x140/0x140 [ 41.686990] lock_commit_crosslock+0xe73/0x1d10 [ 41.691633] ? lock_commit_crosslock+0xe73/0x1d10 [ 41.696446] ? check_prev_add+0x1520/0x1520 [ 41.700739] ? lock_acquire+0x1d5/0x580 [ 41.704686] ? complete+0x18/0x80 [ 41.708112] ? lock_release+0xd70/0xd70 [ 41.712067] ? find_held_lock+0x39/0x1d0 [ 41.716099] complete+0x24/0x80 [ 41.719349] submit_bio_wait_endio+0x9c/0xd0 [ 41.723826] ? bio_iov_iter_get_pages+0x4e0/0x4e0 [ 41.728635] bio_endio+0x2f8/0x8d0 [ 41.732143] ? bio_dirty_fn+0x3e0/0x3e0 [ 41.736089] ? rcu_pm_notify+0xc0/0xc0 [ 41.739945] ? bio_advance+0xf8/0x370 [ 41.743714] blk_update_request+0x2a6/0xe20 [ 41.748010] ? blk_account_io_completion+0x410/0x410 [ 41.753087] blk_mq_end_request+0x54/0x120 [ 41.757297] lo_complete_rq+0xbe/0x1f0 [ 41.761153] __blk_mq_complete_request+0x38f/0x6c0 [ 41.766061] blk_mq_complete_request+0x4f/0x60 [ 41.770620] loop_queue_work+0x26b/0x3900 [ 41.774737] ? do_raw_spin_trylock+0x190/0x190 [ 41.779294] ? lo_rw_aio+0x1e70/0x1e70 [ 41.783151] ? _raw_spin_unlock_irq+0x27/0x70 [ 41.787615] ? finish_task_switch+0x1d3/0x740 [ 41.792078] ? finish_task_switch+0x1aa/0x740 [ 41.796541] ? preempt_notifier_dec+0x20/0x20 [ 41.801009] ? check_noncircular+0x20/0x20 [ 41.805213] ? __schedule+0x8f0/0x2070 [ 41.809071] ? do_raw_spin_trylock+0x190/0x190 [ 41.813626] ? lock_release+0xd70/0xd70 [ 41.817572] ? compat_start_thread+0x80/0x80 [ 41.821955] ? find_held_lock+0x39/0x1d0 [ 41.825991] ? finish_task_switch+0x1aa/0x740 [ 41.830459] ? kthread_worker_fn+0x4ad/0x9b0 [ 41.834838] ? do_raw_spin_trylock+0x190/0x190 [ 41.839394] ? check_same_owner+0x320/0x320 [ 41.843688] ? _raw_spin_unlock_irq+0x27/0x70 [ 41.848161] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 41.853157] kthread_worker_fn+0x340/0x9b0 [ 41.857361] ? kthread_flush_work+0x560/0x560 [ 41.861839] ? lock_downgrade+0x990/0x990 [ 41.865964] ? complete+0x18/0x80 [ 41.