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-1,10.128.0.24' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 39.359182] [ 39.360874] ====================================================== [ 39.367154] WARNING: possible circular locking dependency detected [ 39.373438] 4.14.0-rc1-next-20170918+ #24 Not tainted [ 39.378590] ------------------------------------------------------ [ 39.384871] loop0/2988 is trying to acquire lock: [ 39.389677] (&sb->s_type->i_mutex_key#9){++++}, at: [] generic_file_write_iter+0xdc/0x7a0 [ 39.399621] [ 39.399621] but now in release context of a crosslock acquired at the following: [ 39.408603] ((complete)&ret.event){+.+.}, at: [] submit_bio_wait+0x15e/0x200 [ 39.417411] [ 39.417411] which lock already depends on the new lock. [ 39.417411] [ 39.425689] [ 39.425689] the existing dependency chain (in reverse order) is: [ 39.433273] [ 39.433273] -> #4 ((complete)&ret.event){+.+.}: [ 39.439392] __lock_acquire+0x328f/0x4620 [ 39.444034] lock_acquire+0x1d5/0x580 [ 39.448330] wait_for_completion_io+0xc8/0x770 [ 39.453405] submit_bio_wait+0x15e/0x200 [ 39.457952] blkdev_issue_zeroout+0x13c/0x1d0 [ 39.462943] ext4_init_inode_table+0x4fd/0xdb1 [ 39.468010] ext4_lazyinit_thread+0x81a/0xd40 [ 39.472990] kthread+0x39c/0x470 [ 39.476843] ret_from_fork+0x2a/0x40 [ 39.481039] [ 39.481039] -> #3 (&meta_group_info[i]->alloc_sem){++++}: [ 39.488029] __lock_acquire+0x328f/0x4620 [ 39.492673] lock_acquire+0x1d5/0x580 [ 39.496958] down_read+0x96/0x150 [ 39.500907] __ext4_new_inode+0x26dc/0x4f00 [ 39.505721] ext4_symlink+0x2d9/0xae0 [ 39.510005] vfs_symlink+0x323/0x560 [ 39.514212] SyS_symlink+0x134/0x200 [ 39.518409] entry_SYSCALL_64_fastpath+0x1f/0xbe [ 39.523648] [ 39.523648] -> #2 (jbd2_handle){.+.+}: [ 39.528982] __lock_acquire+0x328f/0x4620 [ 39.533614] lock_acquire+0x1d5/0x580 [ 39.537918] start_this_handle+0x4b8/0x1080 [ 39.542735] jbd2__journal_start+0x389/0x9f0 [ 39.547638] __ext4_journal_start_sb+0x15f/0x550 [ 39.552879] ext4_dirty_inode+0x56/0xa0 [ 39.557339] __mark_inode_dirty+0x912/0x1170 [ 39.562233] generic_update_time+0x1b2/0x270 [ 39.567127] touch_atime+0x26d/0x2f0 [ 39.571325] ext4_file_mmap+0x161/0x1b0 [ 39.575786] mmap_region+0xa99/0x15a0 [ 39.580084] do_mmap+0x6a1/0xd50 [ 39.583936] vm_mmap_pgoff+0x1de/0x280 [ 39.588307] SyS_mmap_pgoff+0x462/0x5f0 [ 39.592783] SyS_mmap+0x16/0x20 [ 39.596562] entry_SYSCALL_64_fastpath+0x1f/0xbe [ 39.601803] [ 39.601803] -> #1 (&mm->mmap_sem){++++}: [ 39.607312] __lock_acquire+0x328f/0x4620 [ 39.611946] lock_acquire+0x1d5/0x580 [ 39.616232] __might_fault+0x13a/0x1d0 [ 39.620604] _copy_to_user+0x2c/0xc0 [ 39.624812] filldir+0x1a7/0x320 [ 39.628664] dcache_readdir+0x12d/0x5e0 [ 39.633123] iterate_dir+0x4b2/0x5d0 [ 39.637331] SyS_getdents+0x225/0x450 [ 39.641617] entry_SYSCALL_64_fastpath+0x1f/0xbe [ 39.646864] [ 39.646864] -> #0 (&sb->s_type->i_mutex_key#9){++++}: [ 39.653511] down_write+0x87/0x120 [ 39.657536] generic_file_write_iter+0xdc/0x7a0 [ 39.662690] do_iter_readv_writev+0x531/0x7f0 [ 39.667668] do_iter_write+0x15a/0x540 [ 39.672040] vfs_iter_write+0x77/0xb0 [ 39.676322] [ 39.676322] other info that might help us debug this: [ 39.676322] [ 39.684438] Chain exists of: [ 39.684438] &sb->s_type->i_mutex_key#9 --> &meta_group_info[i]->alloc_sem --> (complete)&ret.event [ 39.684438] [ 39.698025] Possible unsafe locking scenario by crosslock: [ 39.698025] [ 39.705182] CPU0 CPU1 [ 39.709813] ---- ---- [ 39.714442] lock(&meta_group_info[i]->alloc_sem); [ 39.719433] lock((complete)&ret.event); [ 39.723545] lock(&sb->s_type->i_mutex_key#9); [ 39.730694] unlock((complete)&ret.event); [ 39.737497] [ 39.737497] *** DEADLOCK *** [ 39.737497] [ 39.743520] 1 lock held by loop0/2988: [ 39.747367] #0: (&x->wait#14){..-.}, at: [] complete+0x18/0x80 [ 39.755062] [ 39.755062] stack backtrace: [ 39.759526] CPU: 0 PID: 2988 Comm: loop0 Not tainted 4.14.0-rc1-next-20170918+ #24 [ 39.767206] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 39.776524] Call Trace: [ 39.779082] dump_stack+0x194/0x257 [ 39.782675] ? arch_local_irq_restore+0x53/0x53 [ 39.787312] print_circular_bug+0x503/0x710 [ 39.791609] ? print_circular_bug_entry+0xb0/0xb0 [ 39.796416] ? debug_check_no_locks_freed+0x3d0/0x3d0 [ 39.801570] check_prev_add+0x865/0x1520 [ 39.805597] ? shmem_unused_huge_scan+0x160/0x160 [ 39.810401] ? graph_lock+0x170/0x170 [ 39.814167] ? check_usage+0xb70/0xb70 [ 39.818024] ? memcpy+0x45/0x50 [ 39.821269] ? iov_iter_advance+0x2a1/0x13f0 [ 39.825642] ? hlock_class+0x140/0x140 [ 39.829494] lock_commit_crosslock+0xe73/0x1d10 [ 39.834128] ? lock_commit_crosslock+0xe73/0x1d10 [ 39.838946] ? check_prev_add+0x1520/0x1520 [ 39.843232] ? lock_acquire+0x1d5/0x580 [ 39.847170] ? complete+0x18/0x80 [ 39.850590] ? lock_release+0xd70/0xd70 [ 39.854529] ? find_held_lock+0x39/0x1d0 [ 39.858561] complete+0x24/0x80 [ 39.861807] submit_bio_wait_endio+0x9c/0xd0 [ 39.866179] ? bio_iov_iter_get_pages+0x4e0/0x4e0 [ 39.870984] bio_endio+0x2f8/0x8d0 [ 39.874489] ? bio_dirty_fn+0x3e0/0x3e0 [ 39.878435] ? rcu_pm_notify+0xc0/0xc0 [ 39.882300] ? bio_advance+0xf8/0x370 [ 39.886070] blk_update_request+0x2a6/0xe20 [ 39.890356] ? blk_account_io_completion+0x410/0x410 [ 39.895426] blk_mq_end_request+0x54/0x120 [ 39.899632] lo_complete_rq+0xbe/0x1f0 [ 39.903488] __blk_mq_complete_request+0x38f/0x6c0 [ 39.908383] blk_mq_complete_request+0x4f/0x60 [ 39.912930] loop_queue_work+0x26b/0x3900 [ 39.917053] ? do_raw_spin_trylock+0x190/0x190 [ 39.921610] ? lo_rw_aio+0x1e70/0x1e70 [ 39.925462] ? _raw_spin_unlock_irq+0x27/0x70 [ 39.929935] ? finish_task_switch+0x1d3/0x740 [ 39.934393] ? finish_task_switch+0x1aa/0x740 [ 39.938853] ? preempt_notifier_dec+0x20/0x20 [ 39.943325] ? check_noncircular+0x20/0x20 [ 39.947540] ? __schedule+0x8f0/0x2070 [ 39.951403] ? do_raw_spin_trylock+0x190/0x190 [ 39.955953] ? lock_release+0xd70/0xd70 [ 39.960502] ? find_held_lock+0x39/0x1d0 [ 39.964532] ? kthread_worker_fn+0x4ad/0x9b0 [ 39.968906] ? do_raw_spin_trylock+0x190/0x190 [ 39.973452] ? check_same_owner+0x320/0x320 [ 39.977738] ? _raw_spin_unlock_irq+0x27/0x70 [ 39.982198] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 39.987180] kthread_worker_fn+0x340/0x9b0 [ 39.991381] ? kthread_flush_work+0x560/0x560 [ 39.995842] ? lock_downgrade+0x990/0x990 [ 39.999957] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 40.004935] ? schedule+0x108/0x440 [ 40.008534] ? __schedule+0x2070/0x2070