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:26504 pid:11    tgid:11    ppid:2      task_flags:0x4208060 flags:0x00080000
Workqueue: kblockd blk_mq_requeue_work
Call Trace:
 <TASK>
 __schedule+0x17b4/0x5680
 schedule+0x164/0x360
 schedule_timeout+0x158/0x2c0
 nbd_queue_rq+0x857/0x1100
 blk_mq_dispatch_rq_list+0xa70/0x1910
 __blk_mq_sched_dispatch_requests+0xdcc/0x1600
 blk_mq_sched_dispatch_requests+0xd7/0x190
 blk_mq_run_hw_queue+0x348/0x4f0
 blk_mq_run_hw_queues+0x26c/0x3f0
 blk_mq_requeue_work+0x71c/0x780
 process_scheduled_works+0xb5d/0x1860
 worker_thread+0xa53/0xfc0
 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: ffff8881026cf140 ((wq_completion)kblockd){+.+.}-{0:0}, at: process_scheduled_works+0xa35/0x1860
 #1: ffffc90000107c40 ((work_completion)(&(&q->requeue_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0xa70/0x1860
 #2: ffff88811fe00c98 (set->srcu){.+.+}-{0:0}, at: blk_mq_run_hw_queue+0x31f/0x4f0
 #3: ffff888073379978 (&cmd->lock){+.+.}-{4:4}, at: nbd_queue_rq+0xc6/0x1100
1 lock held by khungtaskd/34:
 #0: ffffffff8e95cd60 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
2 locks held by getty/5435:
 #0: ffff8881770a60a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70
 #1: ffffc900034732e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45c/0x13a0
1 lock held by udevd/7430:
 #0: ffff888043c78350 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xe0/0xd30

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

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/0x300
 sys_info+0x135/0x170
 watchdog+0xfd3/0x1030
 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: 23 Comm: ksoftirqd/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:unwind_next_frame+0x223/0x2550
Code: 86 73 04 00 00 44 89 f8 4c 8d 2c 85 80 6b 71 91 4c 89 e8 48 c1 e8 03 0f b6 04 28 84 c0 48 89 eb 0f 85 85 1d 00 00 45 8b 6d 00 <44> 89 f8 ff c0 48 8d 2c 85 80 6b 71 91 48 89 e8 48 c1 e8 03 0f b6
RSP: 0018:ffffc900001d7438 EFLAGS: 00000246
RAX: 0000000000000000 RBX: dffffc0000000000 RCX: 0000000080000100
RDX: 00000000000aad8d RSI: ffffffff8c28adc0 RDI: ffffffff8c28ad80
RBP: dffffc0000000000 R08: ffffffff8176f256 R09: ffffffff8e95cd60
R10: ffffc900001d7558 R11: ffffffff81b0e910 R12: ffffffff8975533c
R13: 000000000017dd4c R14: ffffc900001d7508 R15: 0000000000087553
FS:  0000000000000000(0000) GS:ffff8882a9287000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f78c71e8158 CR3: 0000000109882000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 arch_stack_walk+0x11b/0x150
 stack_trace_save+0xa9/0x100
 kasan_save_track+0x3e/0x80
 kasan_save_free_info+0x46/0x50
 __kasan_slab_free+0x5c/0x80
 kfree+0x1c5/0x640
 skb_release_data+0x828/0xa60
 __kfree_skb+0x5d/0x210
 skb_queue_purge_reason+0x2ee/0x3b0
 netlink_sock_destruct+0x2d/0x1a0
 __sk_destruct+0x8d/0x9d0
 rcu_core+0x7cd/0x1070
 handle_softirqs+0x22a/0x840
 run_ksoftirqd+0x36/0x60
 smpboot_thread_fn+0x541/0xa50
 kthread+0x388/0x470
 ret_from_fork+0x514/0xb70
 ret_from_fork_asm+0x1a/0x30
 </TASK>
