syzbot

INFO: task syz-executor.2:9370 blocked for more than 143 seconds.
      Not tainted 6.8.0-rc7-syzkaller-g707081b61156 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor.2  state:D stack:0     pid:9370  tgid:9369  ppid:6193   flags:0x00000005
Call trace:
 __switch_to+0x314/0x560 arch/arm64/kernel/process.c:553
 context_switch kernel/sched/core.c:5400 [inline]
 __schedule+0x1498/0x24b4 kernel/sched/core.c:6727
 __schedule_loop kernel/sched/core.c:6802 [inline]
 schedule+0xb8/0x19c kernel/sched/core.c:6817
 blk_mq_freeze_queue_wait+0xf4/0x174 block/blk-mq.c:139
 blk_freeze_queue+0xc8/0x104 block/blk-mq.c:166
 blk_mq_freeze_queue+0x20/0x30 block/blk-mq.c:175
 nbd_add_socket+0x174/0x770 drivers/block/nbd.c:1144
 __nbd_ioctl drivers/block/nbd.c:1487 [inline]
 nbd_ioctl+0x210/0xc38 drivers/block/nbd.c:1544
 blkdev_ioctl+0x3e4/0xae4 block/ioctl.c:634
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:871 [inline]
 __se_sys_ioctl fs/ioctl.c:857 [inline]
 __arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:857
 __invoke_syscall arch/arm64/kernel/syscall.c:34 [inline]
 invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:48
 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:133
 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:152
 el0_svc+0x54/0x168 arch/arm64/kernel/entry-common.c:712
 el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:730
 el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:598
INFO: task syz-executor.2:9377 blocked for more than 143 seconds.
      Not tainted 6.8.0-rc7-syzkaller-g707081b61156 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor.2  state:D stack:0     pid:9377  tgid:9369  ppid:6193   flags:0x0000000d
Call trace:
 __switch_to+0x314/0x560 arch/arm64/kernel/process.c:553
 context_switch kernel/sched/core.c:5400 [inline]
 __schedule+0x1498/0x24b4 kernel/sched/core.c:6727
 __schedule_loop kernel/sched/core.c:6802 [inline]
 schedule+0xb8/0x19c kernel/sched/core.c:6817
 schedule_preempt_disabled+0x18/0x2c kernel/sched/core.c:6874
 __mutex_lock_common+0xbd8/0x21a0 kernel/locking/mutex.c:684
 __mutex_lock kernel/locking/mutex.c:752 [inline]
 mutex_lock_nested+0x2c/0x38 kernel/locking/mutex.c:804
 nbd_start_device_ioctl drivers/block/nbd.c:1444 [inline]
 __nbd_ioctl drivers/block/nbd.c:1504 [inline]
 nbd_ioctl+0x8d8/0xc38 drivers/block/nbd.c:1544
 blkdev_ioctl+0x3e4/0xae4 block/ioctl.c:634
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:871 [inline]
 __se_sys_ioctl fs/ioctl.c:857 [inline]
 __arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:857
 __invoke_syscall arch/arm64/kernel/syscall.c:34 [inline]
 invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:48
 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:133
 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:152
 el0_svc+0x54/0x168 arch/arm64/kernel/entry-common.c:712
 el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:730
 el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:598

Showing all locks held in the system:
1 lock held by khungtaskd/29:
 #0: ffff80008ee74ac0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0xc/0x44 include/linux/rcupdate.h:297
2 locks held by getty/5926:
 #0: ffff0000c19040a0 (&tty->ldisc_sem){++++}-{0:0}, at: ldsem_down_read+0x3c/0x4c drivers/tty/tty_ldsem.c:340
 #1: ffff800093fe02f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x41c/0x1228 drivers/tty/n_tty.c:2201
1 lock held by udevd/6342:
 #0: ffff0000ca14f4c8 (&disk->open_mutex){+.+.}-{3:3}, at: bdev_open_by_dev+0x180/0x7ec block/bdev.c:859
1 lock held by syz-executor.2/9370:
 #0: ffff0000ca190198 (&nbd->config_lock){+.+.}-{3:3}, at: nbd_ioctl+0x128/0xc38 drivers/block/nbd.c:1537
1 lock held by syz-executor.2/9377:
 #0: ffff0000ca190198 (&nbd->config_lock){+.+.}-{3:3}, at: nbd_start_device_ioctl drivers/block/nbd.c:1444 [inline]
 #0: ffff0000ca190198 (&nbd->config_lock){+.+.}-{3:3}, at: __nbd_ioctl drivers/block/nbd.c:1504 [inline]
 #0: ffff0000ca190198 (&nbd->config_lock){+.+.}-{3:3}, at: nbd_ioctl+0x8d8/0xc38 drivers/block/nbd.c:1544

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