INFO: task kworker/1:1H:1134 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/1:1H    state:D stack:27296 pid:1134  tgid:1134  ppid:2      task_flags:0x4208060 flags:0x00080000
Workqueue: kblockd blk_mq_run_work_fn
Call Trace:
 <TASK>
 __schedule+0x17db/0x58f0
 schedule+0x164/0x2b0
 schedule_timeout+0x152/0x2c0
 nbd_queue_rq+0x96f/0xff0
 blk_mq_dispatch_rq_list+0x499/0x1990
 __blk_mq_sched_dispatch_requests+0xd36/0x1580
 blk_mq_sched_dispatch_requests+0xd7/0x190
 blk_mq_run_work_fn+0x16c/0x300
 process_scheduled_works+0xc3d/0x1630
 worker_thread+0xa47/0xfb0
 kthread+0x38b/0x480
 ret_from_fork+0x514/0xb70
 ret_from_fork_asm+0x1a/0x30
 </TASK>

Showing all locks held in the system:
locks held by khungtaskd/36: 1, last CPU#0:
 #0: ffffffff8ed5c8e0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
locks held by kworker/1:1H/1134: 4, on CPU#1:
 #0: ffff8881032eb540 ((wq_completion)kblockd){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #1: ffffc90006a07c40 ((work_completion)(&(&hctx->run_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #2: ffff888109acde18 (set->srcu){.+.+}-{0:0}, at: blk_mq_run_work_fn+0x144/0x300
 #3: ffff888109ed0178 (&cmd->lock){+.+.}-{4:4}, at: nbd_queue_rq+0xc1/0xff0
locks held by getty/5418: 2, on CPU#1:
 #0: ffff8881172d90a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70
 #1: ffffc900034832e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45a/0x1360
locks held by kworker/0:5/5699: 3, on CPU#0:
 #0: ffff88810006b140 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #1: ffffc900061efc40 ((work_completion)(&data->fib_event_work)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #2: ffff88801b91e250 (&data->fib_lock){+.+.}-{4:4}, at: nsim_fib_event_work+0x1fd/0x3b0
locks held by udevd/21207: 1, on CPU#0:
 #0: ffff888109df2350 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xde/0xd70
locks held by kworker/1:22/26465: 3, on CPU#1:
 #0: ffff88810006b140 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #1: ffffc900042b7c40 ((work_completion)(&data->fib_event_work)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #2: ffff88810b5ca250 (&data->fib_lock){+.+.}-{4:4}, at: nsim_fib_event_work+0x1fd/0x3b0

=============================================

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 36 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150
 nmi_cpu_backtrace+0x274/0x2d0
 nmi_trigger_cpumask_backtrace+0x17d/0x390
 sys_info+0x135/0x170
 watchdog+0xfd7/0x1030
 kthread+0x38b/0x480
 ret_from_fork+0x514/0xb70
 ret_from_fork_asm+0x1a/0x30
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:pv_native_safe_halt+0xf/0x20
Code: 6c 88 02 c3 cc cc cc cc cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa eb 07 0f 00 2d b3 71 23 00 fb f4 <e9> 8c 08 03 00 cc cc cc cc cc cc cc cc cc cc cc cc 90 90 90 90 90
RSP: 0018:ffffc900001a7e40 EFLAGS: 00000206
RAX: 0000000000435247 RBX: ffffffff819bb370 RCX: 8000000000000001
RDX: 0000000000000001 RSI: ffffffff8e415be2 RDI: ffffffff8c6da080
RBP: ffffc900001a7f10 R08: ffff88823c633a1b R09: 1ffff110478c6743
R10: dffffc0000000000 R11: ffffed10478c6744 R12: 0000000000000000
R13: 1ffff1102c09e000 R14: 1ffff92000034fd0 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8882a8ccd000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f4cecd556c8 CR3: 000000010e32a000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 default_idle+0x9/0x20
 default_idle_call+0x72/0xb0
 do_idle+0x2e0/0x540
 cpu_startup_entry+0x43/0x60
 start_secondary+0x101/0x110
 common_startup_64+0x13e/0x157
 </TASK>
