INFO: task syz-executor.0:6814 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor.0  state:D stack:0     pid:6814  tgid:6813  ppid:6739   task_flags:0x400140 flags:0x00000019
Call trace:
 __switch_to+0x418/0x87c arch/arm64/kernel/process.c:741 (T)
 context_switch kernel/sched/core.c:5357 [inline]
 __schedule+0x13b0/0x2864 kernel/sched/core.c:6961
 __schedule_loop kernel/sched/core.c:7043 [inline]
 schedule+0xb4/0x230 kernel/sched/core.c:7058
 schedule_timeout+0xac/0x270 kernel/time/sleep_timeout.c:75
 do_wait_for_common+0x288/0x3f8 kernel/sched/completion.c:100
 __wait_for_common kernel/sched/completion.c:121 [inline]
 wait_for_common kernel/sched/completion.c:132 [inline]
 wait_for_completion+0x44/0x5c kernel/sched/completion.c:153
 __flush_workqueue+0x50c/0x109c kernel/workqueue.c:4000
 nbd_start_device_ioctl drivers/block/nbd.c:1551 [inline]
 __nbd_ioctl drivers/block/nbd.c:1612 [inline]
 nbd_ioctl+0x8e8/0xc4c drivers/block/nbd.c:1652
 blkdev_ioctl+0x610/0xac0 block/ioctl.c:705
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:598 [inline]
 __se_sys_ioctl fs/ioctl.c:584 [inline]
 __arm64_sys_ioctl+0x14c/0x1c4 fs/ioctl.c:584
 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
 invoke_syscall+0x98/0x254 arch/arm64/kernel/syscall.c:49
 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132
 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
 el0_svc+0x5c/0x254 arch/arm64/kernel/entry-common.c:744
 el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:763
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596

Showing all locks held in the system:
1 lock held by khungtaskd/32:
 #0: ffff80008fa49aa0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire+0x4/0x48 include/linux/rcupdate.h:330
2 locks held by pr/ttyAMA-1/43:
2 locks held by getty/6330:
 #0: ffff0000d7fc20a0 (&tty->ldisc_sem){++++}-{0:0}, at: ldsem_down_read+0x3c/0x4c drivers/tty/tty_ldsem.c:340
 #1: ffff800099f5e2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x34c/0xfa4 drivers/tty/n_tty.c:2222
2 locks held by kworker/u9:2/6554:
 #0: ffff0000cac5b948 ((wq_completion)nbd0-recv){+.+.}-{0:0}, at: process_one_work+0x63c/0x155c kernel/workqueue.c:3210
 #1: ffff8000a5e97be0 ((work_completion)(&args->work)){+.+.}-{0:0}, at: process_one_work+0x6d4/0x155c kernel/workqueue.c:3210
3 locks held by syz-executor.0/10965:
 #0: ffff0000ca7bfa30 (&nbd->config_lock){+.+.}-{4:4}, at: nbd_ioctl+0x124/0xc4c drivers/block/nbd.c:1645
 #1: ffff0000ca793b58 (&q->q_usage_counter(io)#33){++++}-{0:0}, at: blk_mq_freeze_queue include/linux/blk-mq.h:934 [inline]
 #1: ffff0000ca793b58 (&q->q_usage_counter(io)#33){++++}-{0:0}, at: nbd_add_socket+0x188/0x7a8 drivers/block/nbd.c:1251
 #2: ffff0000ca793b90 (&q->q_usage_counter(queue)#17){+.+.}-{0:0}, at: blk_mq_freeze_queue include/linux/blk-mq.h:934 [inline]
 #2: ffff0000ca793b90 (&q->q_usage_counter(queue)#17){+.+.}-{0:0}, at: nbd_add_socket+0x188/0x7a8 drivers/block/nbd.c:1251

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