INFO: task kworker/0:0H:11 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/0:0H    state:D stack:25656 pid:11    tgid:11    ppid:2      task_flags:0x4208060 flags:0x00080000
Workqueue: kblockd blk_mq_run_work_fn
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_work_fn+0x16c/0x300
 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/0:0H/11:
 #0: ffff8881626d9d40 ((wq_completion)kblockd){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0
 #1: ffffc90000107c40 ((work_completion)(&(&hctx->run_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0
 #2: ffff88810ab47998 (set->srcu){.+.+}-{0:0}, at: blk_mq_run_work_fn+0x144/0x300
 #3: ffff888034c78178 (&cmd->lock){+.+.}-{4:4}, at: nbd_queue_rq+0xc1/0x1150
1 lock held by khungtaskd/35:
 #0: ffffffff8eb59c60 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
2 locks held by getty/5436:
 #0: ffff888172bd90a0 (&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/23749:
 #0: ffff88810b411350 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xde/0xd70
1 lock held by udevd/24105:
 #0: ffff88810b415350 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xde/0xd70
1 lock held by udevd/24847:
 #0: ffff88810b589350 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xde/0xd70
1 lock held by syz.0.18193/32352:
 #0: ffff888044d54440 (&sb->s_type->i_mutex_key#13){+.+.}-{4:4}, at: sock_close+0x82/0x220

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

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 35 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: 26 Comm: kworker/u9:0 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
Workqueue:  0x0 (events_unbound)
RIP: 0010:assign_work+0xc1/0x5d0
Code: ed 03 00 00 e8 50 e1 37 00 eb 05 e8 49 e1 37 00 4d 8d 74 24 18 4c 89 f0 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df 80 3c 08 00 <74> 08 4c 89 f7 e8 25 74 a5 00 49 8b 1e 48 81 fb 90 3f 8f 81 0f 84
RSP: 0018:ffffc90000a17c98 EFLAGS: 00000046
RAX: 1ffff11005c5ab03 RBX: dffffc0000000000 RCX: dffffc0000000000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: 0000000000000001 R08: ffff8881000bbc87 R09: 1ffff11020017790
R10: dffffc0000000000 R11: ffffed1020017791 R12: ffff88802e2d5800
R13: 0000000000000000 R14: ffff88802e2d5818 R15: ffff8881032c9000
FS:  0000000000000000(0000) GS:ffff8882a8f54000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fc9f15ef4b8 CR3: 000000010e700000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 worker_thread+0xa36/0xfb0
 kthread+0x388/0x470
 ret_from_fork+0x514/0xb70
 ret_from_fork_asm+0x1a/0x30
 </TASK>
