INFO: task syz-executor1:14664 blocked for more than 120 seconds. Not tainted 4.17.0+ #86 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor1 D24824 14664 4559 0x00000004 Call Trace: context_switch kernel/sched/core.c:2856 [inline] __schedule+0x801/0x1e30 kernel/sched/core.c:3498 schedule+0xef/0x430 kernel/sched/core.c:3542 blk_queue_enter+0x8da/0xdf0 block/blk-core.c:949 generic_make_request+0x651/0x1790 block/blk-core.c:2382 submit_bio+0xba/0x460 block/blk-core.c:2555 submit_bio_wait+0x134/0x1e0 block/bio.c:977 blkdev_issue_flush+0x204/0x300 block/blk-flush.c:548 blkdev_fsync+0x93/0xd0 fs/block_dev.c:629 vfs_fsync_range+0x140/0x220 fs/sync.c:197 vfs_fsync+0x29/0x30 fs/sync.c:211 __loop_update_dio+0x4de/0x6a0 drivers/block/loop.c:207 loop_update_dio drivers/block/loop.c:621 [inline] loop_change_fd drivers/block/loop.c:695 [inline] lo_ioctl+0xd28/0x2190 drivers/block/loop.c:1402 __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/0x16f0 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 Code: ac 24 38 01 00 00 48 81 c4 40 01 00 00 c3 c6 84 24 60 01 00 00 00 48 8b ac 24 38 01 00 00 48 81 c4 40 01 00 00 c3 c6 84 24 60 <01> 00 00 01 48 8b ac 24 38 01 00 00 48 81 c4 40 01 00 00 c3 c6 84 RSP: 002b:00007f737e0bfc68 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f737e0c06d4 RCX: 0000000000455a09 RDX: 0000000000000013 RSI: 0000000000004c06 RDI: 0000000000000013 RBP: 000000000072bf50 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000000002d4 R14: 00000000006f9480 R15: 0000000000000001 Showing all locks held in the system: 2 locks held by khungtaskd/896: #0: 00000000bc2900e7 (rcu_read_lock){....}, at: check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline] #0: 00000000bc2900e7 (rcu_read_lock){....}, at: watchdog+0x1ff/0xf60 kernel/hung_task.c:249 #1: 00000000bc2900e7 (rcu_read_lock){....}, at: debug_show_all_locks+0xc8/0x40c kernel/locking/lockdep.c:4461 1 lock held by rsyslogd/4389: 2 locks held by getty/4480: #0: 000000001759240b (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000b89230d5 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4481: #0: 00000000be083b6b (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000f353e6ec (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4482: #0: 00000000f2a6db24 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 0000000087a59c6b (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4483: #0: 000000006a714818 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 000000007acbe372 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4484: #0: 00000000560bcb5d (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000f95f35f4 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4485: #0: 000000008e7cd9f9 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000c266abfc (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4486: #0: 00000000af7fa523 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 0000000072a93181 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 1 lock held by syz-executor0/4558: #0: 0000000014977f51 (&lo->lo_ctl_mutex/1){+.+.}, at: lo_ioctl+0x8d/0x2190 drivers/block/loop.c:1393 1 lock held by syz-executor1/14664: #0: 0000000014977f51 (&lo->lo_ctl_mutex/1){+.+.}, at: lo_ioctl+0x8d/0x2190 drivers/block/loop.c:1393 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 896 Comm: khungtaskd Not tainted 4.17.0+ #86 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 0 to CPUs 1: NMI backtrace for cpu 1 skipped: idling at native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:54