netlink: 3 bytes leftover after parsing attributes in process `syz-executor1'. ====================================================== WARNING: possible circular locking dependency detected 4.14.0-rc4+ #125 Not tainted ------------------------------------------------------ loop0/15496 is trying to acquire lock: (&sb->s_type->i_mutex_key#9){++++}, at: [] inode_lock include/linux/fs.h:712 [inline] (&sb->s_type->i_mutex_key#9){++++}, at: [] shmem_fallocate+0x161/0x1160 mm/shmem.c:2841 but now in release context of a crosslock acquired at the following: ((complete)&ret.event){+.+.}, at: [] submit_bio_wait+0x15e/0x200 block/bio.c:953 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #4 ((complete)&ret.event){+.+.}: check_prevs_add kernel/locking/lockdep.c:2020 [inline] validate_chain kernel/locking/lockdep.c:2469 [inline] __lock_acquire+0x328f/0x4620 kernel/locking/lockdep.c:3498 lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:4002 complete_acquire include/linux/completion.h:39 [inline] __wait_for_common kernel/sched/completion.c:108 [inline] wait_for_common_io kernel/sched/completion.c:128 [inline] wait_for_completion_io+0xcb/0x7b0 kernel/sched/completion.c:176 submit_bio_wait+0x15e/0x200 block/bio.c:953 blkdev_issue_zeroout+0x13c/0x1d0 block/blk-lib.c:370 sb_issue_zeroout include/linux/blkdev.h:1368 [inline] ext4_init_inode_table+0x4fd/0xdb1 fs/ext4/ialloc.c:1447 ext4_run_li_request fs/ext4/super.c:2866 [inline] ext4_lazyinit_thread+0x808/0xd30 fs/ext4/super.c:2960 kthread+0x39c/0x470 kernel/kthread.c:231 ret_from_fork+0x2a/0x40 arch/x86/entry/entry_64.S:431 -> #3 (&meta_group_info[i]->alloc_sem){++++}: check_prevs_add kernel/locking/lockdep.c:2020 [inline] validate_chain kernel/locking/lockdep.c:2469 [inline] __lock_acquire+0x328f/0x4620 kernel/locking/lockdep.c:3498 lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:4002 down_read+0x96/0x150 kernel/locking/rwsem.c:23 __ext4_new_inode+0x26dc/0x4f00 fs/ext4/ialloc.c:1056 ext4_symlink+0x2d9/0xae0 fs/ext4/namei.c:3118 vfs_symlink+0x323/0x560 fs/namei.c:4115 SYSC_symlinkat fs/namei.c:4142 [inline] SyS_symlinkat fs/namei.c:4122 [inline] SYSC_symlink fs/namei.c:4155 [inline] SyS_symlink+0x134/0x200 fs/namei.c:4153 entry_SYSCALL_64_fastpath+0x1f/0xbe -> #2 (jbd2_handle){++++}: check_prevs_add kernel/locking/lockdep.c:2020 [inline] validate_chain kernel/locking/lockdep.c:2469 [inline] __lock_acquire+0x328f/0x4620 kernel/locking/lockdep.c:3498 lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:4002 start_this_handle+0x4b8/0x1080 fs/jbd2/transaction.c:390 jbd2__journal_start+0x389/0x9f0 fs/jbd2/transaction.c:444 __ext4_journal_start_sb+0x15f/0x550 fs/ext4/ext4_jbd2.c:80 __ext4_journal_start fs/ext4/ext4_jbd2.h:314 [inline] ext4_dirty_inode+0x56/0xa0 fs/ext4/inode.c:5859 __mark_inode_dirty+0x912/0x1170 fs/fs-writeback.c:2096 generic_update_time+0x1b2/0x270 fs/inode.c:1649 update_time fs/inode.c:1665 [inline] touch_atime+0x26d/0x2f0 fs/inode.c:1737 file_accessed include/linux/fs.h:2061 [inline] ext4_file_mmap+0x161/0x1b0 fs/ext4/file.c:352 call_mmap include/linux/fs.h:1775 [inline] mmap_region+0xa99/0x15a0 mm/mmap.c:1690 do_mmap+0x6a1/0xd50 mm/mmap.c:1468 do_mmap_pgoff include/linux/mm.h:2150 [inline] vm_mmap_pgoff+0x1de/0x280 mm/util.c:333 SYSC_mmap_pgoff mm/mmap.c:1518 [inline] SyS_mmap_pgoff+0x462/0x5f0 mm/mmap.c:1476 SYSC_mmap arch/x86/kernel/sys_x86_64.c:99 [inline] SyS_mmap+0x16/0x20 arch/x86/kernel/sys_x86_64.c:90 entry_SYSCALL_64_fastpath+0x1f/0xbe -> #1 (&mm->mmap_sem){++++}: check_prevs_add kernel/locking/lockdep.c:2020 [inline] validate_chain kernel/locking/lockdep.c:2469 [inline] __lock_acquire+0x328f/0x4620 kernel/locking/lockdep.c:3498 lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:4002 __might_fault+0x13a/0x1d0 mm/memory.c:4502 _copy_to_user+0x2c/0xc0 lib/usercopy.c:24 copy_to_user include/linux/uaccess.h:154 [inline] filldir+0x1a7/0x320 fs/readdir.c:196 dir_emit_dot include/linux/fs.h:3339 [inline] dir_emit_dots include/linux/fs.h:3350 [inline] dcache_readdir+0x12d/0x5e0 fs/libfs.c:192 iterate_dir+0x4b2/0x5d0 fs/readdir.c:51 SYSC_getdents fs/readdir.c:231 [inline] SyS_getdents+0x225/0x450 fs/readdir.c:212 entry_SYSCALL_64_fastpath+0x1f/0xbe -> #0 (&sb->s_type->i_mutex_key#9){++++}: down_write+0x87/0x120 kernel/locking/rwsem.c:53 inode_lock include/linux/fs.h:712 [inline] shmem_fallocate+0x161/0x1160 mm/shmem.c:2841 lo_discard drivers/block/loop.c:434 [inline] do_req_filebacked drivers/block/loop.c:570 [inline] loop_handle_cmd drivers/block/loop.c:1705 [inline] loop_queue_work+0x46f/0x3900 drivers/block/loop.c:1719 kthread_worker_fn+0x32b/0x980 kernel/kthread.c:635 loop_kthread_worker_fn+0x51/0x60 drivers/block/loop.c:836 other info that might help us debug this: Chain exists of: &sb->s_type->i_mutex_key#9 --> &meta_group_info[i]->alloc_sem --> (complete)&ret.event Possible unsafe locking scenario by crosslock: CPU0 CPU1 ---- ---- lock(&meta_group_info[i]->alloc_sem); lock((complete)&ret.event); lock(&sb->s_type->i_mutex_key#9); unlock((complete)&ret.event); *** DEADLOCK *** 1 lock held by loop0/15496: #0: (&x->wait#14){..-.}, at: [] complete+0x18/0x80 kernel/sched/completion.c:34 stack backtrace: CPU: 0 PID: 15496 Comm: loop0 Not tainted 4.14.0-rc4+ #125 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:16 [inline] dump_stack+0x194/0x257 lib/dump_stack.c:52 print_circular_bug+0x503/0x710 kernel/locking/lockdep.c:1259 check_prev_add+0x865/0x1520 kernel/locking/lockdep.c:1894 commit_xhlock kernel/locking/lockdep.c:5015 [inline] commit_xhlocks kernel/locking/lockdep.c:5059 [inline] lock_commit_crosslock+0xe59/0x1d00 kernel/locking/lockdep.c:5098 complete_release_commit include/linux/completion.h:49 [inline] complete+0x24/0x80 kernel/sched/completion.c:39 submit_bio_wait_endio+0x9c/0xd0 block/bio.c:930 bio_endio+0x2f8/0x8d0 block/bio.c:1843 req_bio_endio block/blk-core.c:204 [inline] blk_update_request+0x2a6/0xe20 block/blk-core.c:2746 blk_mq_end_request+0x54/0x120 block/blk-mq.c:509 lo_complete_rq+0xbe/0x1f0 drivers/block/loop.c:463 __blk_mq_complete_request+0x38f/0x6c0 block/blk-mq.c:550 blk_mq_complete_request+0x4f/0x60 block/blk-mq.c:570 loop_handle_cmd drivers/block/loop.c:1710 [inline] loop_queue_work+0x26b/0x3900 drivers/block/loop.c:1719 kthread_worker_fn+0x32b/0x980 kernel/kthread.c:635 loop_kthread_worker_fn+0x51/0x60 drivers/block/loop.c:836 kthread+0x39c/0x470 kernel/kthread.c:231 ret_from_fork+0x2a/0x40 arch/x86/entry/entry_64.S:431 kauditd_printk_skb: 63 callbacks suppressed audit: type=1326 audit(1507676704.393:806): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=kernel pid=18732 comm="syz-executor1" exe="/root/syz-executor1" sig=31 arch=c000003e syscall=202 compat=0 ip=0x4520a9 code=0xffff0000 ------------[ cut here ]------------ WARNING: CPU: 1 PID: 18751 at arch/x86/kernel/traps.c:776 cond_local_irq_disable arch/x86/kernel/traps.c:85 [inline] WARNING: CPU: 1 PID: 18751 at arch/x86/kernel/traps.c:776 do_debug+0x4d8/0x6e0 arch/x86/kernel/traps.c:790