INFO: task syz-executor4:30136 blocked for more than 120 seconds. Not tainted 4.17.0-rc6+ #63 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor4 D25408 30136 4556 0x00000004 Call Trace: context_switch kernel/sched/core.c:2859 [inline] __schedule+0x801/0x1e30 kernel/sched/core.c:3501 schedule+0xef/0x430 kernel/sched/core.c:3545 blk_mq_freeze_queue_wait+0x1ce/0x460 block/blk-mq.c:152 blk_freeze_queue+0x4a/0x80 block/blk-mq.c:181 blk_mq_freeze_queue+0x15/0x20 block/blk-mq.c:190 loop_set_status+0x1ff/0x1010 drivers/block/loop.c:1119 loop_set_status64+0xaa/0x100 drivers/block/loop.c:1305 lo_ioctl+0x6f5/0x2130 drivers/block/loop.c:1421 __blkdev_driver_ioctl block/ioctl.c:303 [inline] blkdev_ioctl+0x9b6/0x2020 block/ioctl.c:601 block_ioctl+0xee/0x130 fs/block_dev.c:1877 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:500 [inline] do_vfs_ioctl+0x1cf/0x16a0 fs/ioctl.c:684 ksys_ioctl+0xa9/0xd0 fs/ioctl.c:701 __do_sys_ioctl fs/ioctl.c:708 [inline] __se_sys_ioctl fs/ioctl.c:706 [inline] __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:706 do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x455a09 RSP: 002b:00007f56f05cac68 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f56f05cb6d4 RCX: 0000000000455a09 RDX: 0000000020000480 RSI: 0000000000004c04 RDI: 0000000000000013 RBP: 000000000072bea0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000000002b4 R14: 00000000006f8180 R15: 0000000000000000 Showing all locks held in the system: 2 locks held by khungtaskd/893: #0: 00000000c59e7c47 (rcu_read_lock){....}, at: check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline] #0: 00000000c59e7c47 (rcu_read_lock){....}, at: watchdog+0x1ff/0xf60 kernel/hung_task.c:249 #1: 00000000d81f11eb (tasklist_lock){.+.+}, at: debug_show_all_locks+0xde/0x34a kernel/locking/lockdep.c:4470 1 lock held by rsyslogd/4388: #0: 00000000a92c03d7 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0x1a9/0x1e0 fs/file.c:766 2 locks held by getty/4479: #0: 00000000058cf8bd (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 0000000074a633a3 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4480: #0: 0000000043520506 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 0000000008f60e57 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4481: #0: 00000000213c9a7f (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 000000002257b76e (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4482: #0: 00000000033ee744 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 000000005713a583 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4483: #0: 00000000b478cd47 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000db992324 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4484: #0: 0000000069510eb5 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000d61466d3 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 1 lock held by syz-executor0/4557: #0: 00000000a75c0d82 (&lo->lo_ctl_mutex/1){+.+.}, at: lo_ioctl+0x8d/0x2130 drivers/block/loop.c:1391 2 locks held by getty/29864: #0: 0000000021aed030 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000566dbb76 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 1 lock held by syz-executor4/30136: #0: 00000000a75c0d82 (&lo->lo_ctl_mutex/1){+.+.}, at: lo_ioctl+0x8d/0x2130 drivers/block/loop.c:1391 1 lock held by blkid/30175: #0: 00000000a75c0d82 (&lo->lo_ctl_mutex/1){+.+.}, at: lo_ioctl+0x8d/0x2130 drivers/block/loop.c:1391 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 893 Comm: khungtaskd Not tainted 4.17.0-rc6+ #63 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1b9/0x294 lib/dump_stack.c:113 nmi_cpu_backtrace.cold.4+0x19/0xce lib/nmi_backtrace.c:103 nmi_trigger_cpumask_backtrace+0x151/0x192 lib/nmi_backtrace.c:62 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38 trigger_all_cpu_backtrace include/linux/nmi.h:138 [inline] check_hung_task kernel/hung_task.c:132 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:190 [inline] watchdog+0xc10/0xf60 kernel/hung_task.c:249 kthread+0x345/0x410 kernel/kthread.c:240 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:412 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 4386 Comm: rs:main Q:Reg Not tainted 4.17.0-rc6+ #63 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:__preempt_count_sub arch/x86/include/asm/preempt.h:81 [inline] RIP: 0010:rcu_is_watching+0xf0/0x140 kernel/rcu/tree.c:1076 RSP: 0018:ffff8801b026ee58 EFLAGS: 00000282 RAX: 0000000000276295 RBX: ffffed003604ddcc RCX: 1ffff1003604ddd0 RDX: dffffc0000000000 RSI: 0000000000000004 RDI: ffff8801dae23690 RBP: ffff8801b026eee8 R08: ffffed003b5c46d3 R09: ffffed003b5c46d2 R10: ffffed003b5c46d2 R11: ffff8801dae23693 R12: 1ffff1003604ddd0 R13: ffff8801dae23690 R14: ffff8801b026eec0 R15: dffffc0000000000 FS: 00007f839bb2d700(0000) GS:ffff8801dae00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffff600400 CR3: 00000001b1a95000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: rcu_read_unlock include/linux/rcupdate.h:684 [inline] jbd2_write_access_granted.part.8+0x320/0x420 fs/jbd2/transaction.c:1067 jbd2_write_access_granted fs/jbd2/transaction.c:1097 [inline] jbd2_journal_get_write_access+0x91/0xc0 fs/jbd2/transaction.c:1087 __ext4_journal_get_write_access+0x5e/0xa0 fs/ext4/ext4_jbd2.c:169 ext4_reserve_inode_write+0x191/0x260 fs/ext4/inode.c:5763 ext4_mark_inode_dirty+0x177/0xb20 fs/ext4/inode.c:5912 ext4_truncate+0x629/0x1640 fs/ext4/inode.c:4486 ext4_truncate_failed_write fs/ext4/truncate.h:16 [inline] ext4_da_write_begin+0x7a4/0x1260 fs/ext4/inode.c:3094 generic_perform_write+0x39a/0x6a0 mm/filemap.c:3139 __generic_file_write_iter+0x26e/0x630 mm/filemap.c:3264 ext4_file_write_iter+0x388/0x1420 fs/ext4/file.c:266 call_write_iter include/linux/fs.h:1784 [inline] new_sync_write fs/read_write.c:474 [inline] __vfs_write+0x64d/0x960 fs/read_write.c:487 vfs_write+0x1f8/0x560 fs/read_write.c:549 ksys_write+0xf9/0x250 fs/read_write.c:598 __do_sys_write fs/read_write.c:610 [inline] __se_sys_write fs/read_write.c:607 [inline] __x64_sys_write+0x73/0xb0 fs/read_write.c:607 do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x7f839d58b19d RSP: 002b:00007f839bb2bf20 EFLAGS: 00000293 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 0000000000000278 RCX: 00007f839d58b19d RDX: 0000000000000278 RSI: 0000000001a7ea90 RDI: 0000000000000005 RBP: 0000000001a7ea90 R08: 0000000001a7ecac R09: 00007f839cf07f57 R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000000 R13: 00007f839bb2c3a0 R14: 0000000000000007 R15: 0000000001a7e890 Code: d2 74 05 80 fa 03 7e 43 49 c1 ec 03 41 89 46 c0 48 ba 00 00 00 00 00 fc ff df 41 c6 04 14 f8 48 01 d3 d1 e8 65 ff 0d 50 9b 9d 7e <48> c7 03 00 00 00 00 83 e0 01 c7 43 08 00 00 00 00 48 83 c4 68