NOHZ: local_softirq_pending 08 NOHZ: local_softirq_pending 08 NOHZ: local_softirq_pending 08 NOHZ: local_softirq_pending 08 NOHZ: local_softirq_pending 08 INFO: task syz-executor.1:18553 blocked for more than 140 seconds. Not tainted 4.14.176-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.1 D28672 18553 6376 0x00000004 Call Trace: schedule+0x8d/0x1b0 kernel/sched/core.c:3428 schedule_timeout+0x946/0xe40 kernel/time/timer.c:1723 do_wait_for_common kernel/sched/completion.c:91 [inline] __wait_for_common kernel/sched/completion.c:112 [inline] wait_for_common kernel/sched/completion.c:123 [inline] wait_for_completion+0x241/0x390 kernel/sched/completion.c:144 flush_workqueue+0x3d1/0x13f0 kernel/workqueue.c:2676 nbd_start_device_ioctl drivers/block/nbd.c:1249 [inline] __nbd_ioctl drivers/block/nbd.c:1320 [inline] nbd_ioctl+0x4e1/0xa30 drivers/block/nbd.c:1360 __blkdev_driver_ioctl block/ioctl.c:297 [inline] blkdev_ioctl+0x91d/0x17d0 block/ioctl.c:594 block_ioctl+0xd9/0x120 fs/block_dev.c:1881 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:500 [inline] do_vfs_ioctl+0x75a/0xfe0 fs/ioctl.c:684 SYSC_ioctl fs/ioctl.c:701 [inline] SyS_ioctl+0x7f/0xb0 fs/ioctl.c:692 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x45c829 RSP: 002b:00007fd22fd21c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00000000004e8b80 RCX: 000000000045c829 RDX: 0000000000000000 RSI: 000000000000ab03 RDI: 0000000000000004 RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 0000000000000403 R14: 00000000004c69fa R15: 00007fd22fd226d4 Showing all locks held in the system: 1 lock held by khungtaskd/1050: #0: (tasklist_lock){.+.+}, at: [] debug_show_all_locks+0x7c/0x21a kernel/locking/lockdep.c:4544 1 lock held by in:imklog/6046: #0: (&f->f_pos_lock){+.+.}, at: [] __fdget_pos+0xa6/0xc0 fs/file.c:769 2 locks held by knbd1-recv/18554: #0: ("knbd%d-recv"nbd->index){+.+.}, at: [] work_static include/linux/workqueue.h:199 [inline] #0: ("knbd%d-recv"nbd->index){+.+.}, at: [] set_work_data kernel/workqueue.c:619 [inline] #0: ("knbd%d-recv"nbd->index){+.+.}, at: [] set_work_pool_and_clear_pending kernel/workqueue.c:646 [inline] #0: ("knbd%d-recv"nbd->index){+.+.}, at: [] process_one_work+0x727/0x1540 kernel/workqueue.c:2087 #1: ((&args->work)){+.+.}, at: [] process_one_work+0x761/0x1540 kernel/workqueue.c:2091 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 1050 Comm: khungtaskd Not tainted 4.14.176-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x13e/0x194 lib/dump_stack.c:58 nmi_cpu_backtrace.cold+0x57/0x93 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x139/0x17e lib/nmi_backtrace.c:62 trigger_all_cpu_backtrace include/linux/nmi.h:140 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:195 [inline] watchdog+0x5e2/0xb80 kernel/hung_task.c:274 kthread+0x30d/0x420 kernel/kthread.c:232 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 3632 Comm: systemd-journal Not tainted 4.14.176-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 task: ffff888094652540 task.stack: ffff888094658000 RIP: 0010:arch_local_save_flags arch/x86/include/asm/paravirt.h:774 [inline] RIP: 0010:check_preemption_disabled+0x7b/0x240 lib/smp_processor_id.c:19 RSP: 0018:ffff88809465fd38 EFLAGS: 00000097 RAX: ffff888094652540 RBX: 00000000014000c0 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffffffff86e45640 RDI: ffffffff86e45680 RBP: ffffffff86e45680 R08: 0000000000001008 R09: ffff88804bbc1800 R10: 000000000000000a R11: ffff888094652540 R12: 0000000000000000 R13: ffffffff86e45640 R14: 0000000000000282 R15: 0000000000035f58 FS: 00007f773e1338c0(0000) GS:ffff8880aea00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f773b646000 CR3: 0000000094c47000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: Code: ba 00 00 00 00 00 fc ff df 48 c1 e8 03 80 3c 10 00 0f 85 0b 01 00 00 48 83 3d a1 25 d3 04 00 0f 84 f6 00 00 00 e8 b6 05 5c fe 9c <58> 0f 1f 44 00 00 f6 c4 02 74 aa e8 a5 05 5c fe 44 89 e0 83 e0