INFO: task syz-executor2:3700 blocked for more than 120 seconds. Not tainted 4.17.0+ #89 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor2 D23432 3700 4599 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: 0033:0x4559f9 Code: 0f 85 e9 f2 ff ff 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 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 RSP: 002b:00007ff013cedc68 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007ff013cee6d4 RCX: 00000000004559f9 RDX: 0000000000000013 RSI: 0000000000004c06 RDI: 0000000000000014 RBP: 000000000072bea0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000004bddfb R14: 00000000004cbc08 R15: 0000000000000000 Showing all locks held in the system: 2 locks held by khungtaskd/897: #0: 0000000069d06f81 (rcu_read_lock){....}, at: check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline] #0: 0000000069d06f81 (rcu_read_lock){....}, at: watchdog+0x1ff/0xf60 kernel/hung_task.c:249 #1: 0000000069d06f81 (rcu_read_lock){....}, at: debug_show_all_locks+0xc8/0x40c kernel/locking/lockdep.c:4461 1 lock held by rsyslogd/4428: #0: 000000005268a19a (&f->f_pos_lock){+.+.}, at: __fdget_pos+0x1a9/0x1e0 fs/file.c:766 2 locks held by getty/4519: #0: 0000000067634414 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000d2fbdc3e (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4520: #0: 00000000575b9c41 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000bd9d1344 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4521: #0: 00000000bdb8b3d3 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000ad2a2248 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4522: #0: 00000000ddd06992 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000388b8aa7 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4523: #0: 00000000a9035948 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000570eb43a (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4524: #0: 00000000f3b67177 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000c5f3fe74 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4525: #0: 000000001d46f113 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000acba4a59 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 1 lock held by syz-executor2/3700: #0: 00000000e37bbf3b (&lo->lo_ctl_mutex/1){+.+.}, at: lo_ioctl+0x8d/0x2190 drivers/block/loop.c:1393 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 897 Comm: khungtaskd Not tainted 4.17.0+ #89 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 skipped: idling at native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:54