INFO: task kworker/0:1H:891 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/0:1H    state:D stack:24968 pid:891   tgid:891   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:
1 lock held by khungtaskd/34:
 #0: ffffffff8e959c20 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
4 locks held by kworker/0:1H/891:
 #0: ffff88816269e140 ((wq_completion)kblockd){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0
 #1: ffffc900065f7c40 ((work_completion)(&(&hctx->run_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0
 #2: ffff8881704fe318 (set->srcu){.+.+}-{0:0}, at: blk_mq_run_work_fn+0x144/0x300
 #3: ffff88811dec0178 (&cmd->lock){+.+.}-{4:4}, at: nbd_queue_rq+0xc1/0x1150
2 locks held by getty/5435:
 #0: ffff88816f7d70a0 (&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/327:
 #0: ffff88816eae5350 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xde/0xd70

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

NMI backtrace for cpu 1
CPU: 1 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 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 8498 Comm: syz.1.10061 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:lock_acquire+0xc1/0x350
Code: 11 85 c0 0f 85 bf 00 00 00 65 48 8b 05 c0 7c 9d 11 83 b8 9c 0b 00 00 00 0f 85 aa 00 00 00 4c 89 74 24 10 4d 89 fe 9c 41 5f fa <48> c7 c7 16 a9 ff 8d e8 b3 9f 11 0a 65 ff 05 7c c1 9d 11 45 31 c9
RSP: 0018:ffffc90020aa7bc0 EFLAGS: 00000046
RAX: ffff888171acbb80 RBX: 0000000000000000 RCX: 0000000080000002
RDX: 0000000000000000 RSI: ffffffff8bb65b40 RDI: 1ffffffff34e70a6
RBP: ffffffff84c384b1 R08: 0000000000000001 R09: 0000000000000000
R10: dffffc0000000000 R11: fffffbfff2065a5f R12: 0000000000000000
R13: ffffffff9a738530 R14: 0000000000000001 R15: 0000000000000046
FS:  0000555577254500(0000) GS:ffff88818dc26000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c32f961 CR3: 00000001bf6b0000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 _raw_spin_lock_irqsave+0x40/0x60
 __debug_object_init+0x81/0x3c0
 hrtimer_nanosleep+0xca/0x3a0
 __se_sys_clock_nanosleep+0x35b/0x3b0
 do_syscall_64+0x174/0x580
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f36a4d5d68e
Code: 08 0f 85 a5 a8 ff ff 49 89 fb 48 89 f0 48 89 d7 48 89 ce 4c 89 c2 4d 89 ca 4c 8b 44 24 08 4c 8b 4c 24 10 4c 89 5c 24 08 0f 05 <c3> 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 80 00 00 00 00 48 83 ec 08
RSP: 002b:00007fff0698a028 EFLAGS: 00000246 ORIG_RAX: 00000000000000e6
RAX: ffffffffffffffda RBX: 0000555577254500 RCX: 00007f36a4d5d68e
RDX: 00007fff0698a080 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007f36a5017da0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000000c2127
R13: 00007f36a501618c R14: 00000000000c1e57 R15: 00007f36a5016180
 </TASK>
