INFO: task kworker/1:0H:25 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/1:0H    state:D stack:26568 pid:25    tgid:25    ppid:2      task_flags:0x4208060 flags:0x00080000
Workqueue: kblockd blk_mq_requeue_work
Call Trace:
 <TASK>
 __schedule+0x17d9/0x56c0
 schedule+0x164/0x2b0
 schedule_timeout+0x152/0x2c0
 nbd_queue_rq+0x889/0x1150
 blk_mq_dispatch_rq_list+0x499/0x1990
 __blk_mq_sched_dispatch_requests+0xd36/0x1580
 blk_mq_sched_dispatch_requests+0xd7/0x190
 blk_mq_run_hw_queue+0x348/0x4f0
 blk_mq_run_hw_queues+0x268/0x3f0
 blk_mq_requeue_work+0x703/0x760
 process_scheduled_works+0xa8e/0x14e0
 worker_thread+0xa47/0xfb0
 kthread+0x388/0x470
 ret_from_fork+0x514/0xb70
 ret_from_fork_asm+0x1a/0x30
 </TASK>

Showing all locks held in the system:
4 locks held by kworker/1:0H/25:
 #0: ffff888161efc940 ((wq_completion)kblockd){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0
 #1: ffffc900001f7c40 ((work_completion)(&(&q->requeue_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0
 #2: ffff88816d048e18 (set->srcu){.+.+}-{0:0}, at: blk_mq_run_hw_queue+0x31f/0x4f0
 #3: ffff888101b80178 (&cmd->lock){+.+.}-{4:4}, at: nbd_queue_rq+0xc1/0x1150
1 lock held by khungtaskd/34:
 #0: ffffffff8eb59c60 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
2 locks held by kworker/1:1H/96:
 #0: ffff888161efc940 ((wq_completion)kblockd){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0
 #1: ffffc900027afc40 ((work_completion)(&q->timeout_work)){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0
2 locks held by getty/5439:
 #0: ffff8881710e10a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70
 #1: ffffc900034732e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45a/0x1360
1 lock held by udevd/2097:
 #0: ffff88816d0b7350 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xde/0xd70

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

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 34 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+0x17a/0x380
 sys_info+0x135/0x170
 watchdog+0xfd7/0x1030
 kthread+0x388/0x470
 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: bc 7e 02 e9 13 05 03 00 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 53 6e 18 00 fb f4 <c3> cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc 90 90 90 90 90
RSP: 0018:ffffc90000197e40 EFLAGS: 00000206
RAX: 000000000055026f RBX: ffffffff819b4450 RCX: 0000000080000001
RDX: 0000000000000001 RSI: ffffffff8e22bfd3 RDI: ffffffff8c4bdb80
RBP: ffffc90000197f10 R08: ffff88823c6338db R09: 1ffff110478c671b
R10: dffffc0000000000 R11: ffffed10478c671c R12: 0000000000000000
R13: 1ffff1102c09d000 R14: 1ffff92000032fd0 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8882a8f50000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fc4fcaf9440 CR3: 000000010f288000 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>
