INFO: task kworker/u4:7:1119 blocked for more than 144 seconds.
      Not tainted 5.16.0-rc1-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u4:7    state:D stack:22072 pid: 1119 ppid:     2 flags:0x00004000
Workqueue: nbd-del nbd_dev_remove_work
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:4972 [inline]
 __schedule+0xb72/0x1460 kernel/sched/core.c:6253
 schedule+0x12b/0x1f0 kernel/sched/core.c:6326
 blk_mq_freeze_queue_wait+0x105/0x190 block/blk-mq.c:178
 del_gendisk+0x6d0/0x790 block/genhd.c:623
 nbd_dev_remove drivers/block/nbd.c:252 [inline]
 nbd_dev_remove_work+0x47/0xe0 drivers/block/nbd.c:269
 process_one_work+0x853/0x1140 kernel/workqueue.c:2298
 worker_thread+0xac1/0x1320 kernel/workqueue.c:2445
 kthread+0x468/0x490 kernel/kthread.c:327
 ret_from_fork+0x1f/0x30
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/26:
 #0: ffffffff8cd1da80 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30
2 locks held by kworker/u4:7/1119:
 #0: ffff88801b73d938 ((wq_completion)nbd-del){+.+.}-{0:0}, at: process_one_work+0x7ca/0x1140
 #1: ffffc90005027d20 ((work_completion)(&nbd->remove_work)){+.+.}-{0:0}, at: process_one_work+0x808/0x1140 kernel/workqueue.c:2273
1 lock held by in:imklog/6209:
 #0: ffff8880186d8d70 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x24e/0x2f0 fs/file.c:990
2 locks held by rs:main Q:Reg/6211:
2 locks held by agetty/6232:
 #0: ffff88801af4e098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:252
 #1: ffffc9000282c2e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x6c5/0x1c60 drivers/tty/n_tty.c:2113
3 locks held by kworker/u5:0/14476:
 #0: ffff88807b67f938 ((wq_completion)hci2){+.+.}-{0:0}, at: process_one_work+0x7ca/0x1140
 #1: ffffc90000da7d20 ((work_completion)(&hdev->power_on)){+.+.}-{0:0}, at: process_one_work+0x808/0x1140 kernel/workqueue.c:2273
 #2: ffff888079c08ff0 (&hdev->req_lock){+.+.}-{3:3}, at: hci_dev_do_open+0xa5/0x1560 net/bluetooth/hci_core.c:1324
3 locks held by kworker/u4:12/25983:
 #0: ffff8880b9a395d8 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x25/0x110 kernel/sched/core.c:478
 #1: ffff8880b9a27888 (&per_cpu_ptr(group->pcpu, cpu)->seq){-.-.}-{0:0}, at: psi_task_switch+0x46c/0x780 kernel/sched/psi.c:871
 #2: ffff8880b9a280d8 (&base->lock){-.-.}-{2:2}, at: lock_timer_base+0x12a/0x270 kernel/time/timer.c:946

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

NMI backtrace for cpu 1
CPU: 1 PID: 26 Comm: khungtaskd Not tainted 5.16.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1dc/0x2d8 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x45f/0x490 lib/nmi_backtrace.c:105
 nmi_trigger_cpumask_backtrace+0x16a/0x280 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:210 [inline]
 watchdog+0xc82/0xcd0 kernel/hung_task.c:295
 kthread+0x468/0x490 kernel/kthread.c:327
 ret_from_fork+0x1f/0x30
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 2965 Comm: systemd-journal Not tainted 5.16.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0033:0x7f003db44c45
Code: 78 63 4d 85 c0 74 7e 4c 8b 4f 28 31 c0 4d 85 c9 74 06 41 3b 71 08 74 0d 48 83 c4 08 c3 0f 1f 84 00 00 00 00 00 39 57 0c 75 ee <48> 8b 57 18 48 39 ca 77 e5 48 03 57 20 49 01 c8 49 39 d0 0f 96 c0
RSP: 002b:00007ffd6af42a50 EFLAGS: 00000246
RAX: 0000000000000000 RBX: 000000000012a788 RCX: 000000000012a788
RDX: 0000000000000003 RSI: 0000000000000016 RDI: 00005617e5401810
RBP: 00005617e53f5040 R08: 0000000000000069 R09: 00005617e54014a0
R10: 4ec784a9bf81d690 R11: e6059afedbcfa22c R12: 0000000000000001
R13: 0000000000000003 R14: 0000000000000016 R15: 00005617e53f93b0
FS:  00007f003df0f8c0 GS:  0000000000000000