INFO: task syz-executor.5:5952 blocked for more than 143 seconds.
      Not tainted 6.8.0-rc1-next-20240124-syzkaller-g8bf1262c53f5 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor.5  state:D stack:28432 pid:5952  tgid:5948  ppid:5430   flags:0x00004006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5400 [inline]
 __schedule+0xf15/0x5ce0 kernel/sched/core.c:6727
 __schedule_loop kernel/sched/core.c:6804 [inline]
 schedule+0xe7/0x350 kernel/sched/core.c:6819
 schedule_timeout+0x258/0x2a0 kernel/time/timer.c:2159
 do_wait_for_common kernel/sched/completion.c:95 [inline]
 __wait_for_common+0x3de/0x5f0 kernel/sched/completion.c:116
 __flush_workqueue+0x3e0/0x1340 kernel/workqueue.c:3199
 nbd_start_device_ioctl drivers/block/nbd.c:1443 [inline]
 __nbd_ioctl drivers/block/nbd.c:1504 [inline]
 nbd_ioctl+0x308/0xd60 drivers/block/nbd.c:1544
 blkdev_ioctl+0x2f7/0x770 block/ioctl.c:636
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:871 [inline]
 __se_sys_ioctl fs/ioctl.c:857 [inline]
 __x64_sys_ioctl+0x193/0x220 fs/ioctl.c:857
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xd2/0x260 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x6d/0x75
RIP: 0033:0x455ae9
RSP: 002b:00007f7f69c350d8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 000000000055bfa8 RCX: 0000000000455ae9
RDX: 0000000000000000 RSI: 000000000000ab03 RDI: 0000000000000003
RBP: 00000000004a166d R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000004a0800
R13: 0000000000000009 R14: 000000000055bfa8 R15: 00007ffd75ce0d68
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/29:
 #0: ffffffff8d7b0c20 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:298 [inline]
 #0: ffffffff8d7b0c20 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:750 [inline]
 #0: ffffffff8d7b0c20 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x75/0x340 kernel/locking/lockdep.c:6614
2 locks held by getty/4823:
 #0: ffff88802b4f50a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243
 #1: ffffc90002efe2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0xfc8/0x1490 drivers/tty/n_tty.c:2201
2 locks held by kworker/u5:3/5440:
 #0: ffff8880208f5538 ((wq_completion)nbd5-recv){+.+.}-{0:0}, at: process_one_work+0x7ba/0x16e0 kernel/workqueue.c:2608
 #1: ffffc90004647d80 ((work_completion)(&args->work)){+.+.}-{0:0}, at: process_one_work+0x824/0x16e0 kernel/workqueue.c:2609

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

NMI backtrace for cpu 1
CPU: 1 PID: 29 Comm: khungtaskd Not tainted 6.8.0-rc1-next-20240124-syzkaller-g8bf1262c53f5 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/17/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xd9/0x1b0 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x27b/0x390 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x29c/0x300 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:222 [inline]
 watchdog+0xf86/0x1210 kernel/hung_task.c:379
 kthread+0x2c1/0x3a0 kernel/kthread.c:388
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:242
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 2443 Comm: kworker/u4:9 Not tainted 6.8.0-rc1-next-20240124-syzkaller-g8bf1262c53f5 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/17/2023
Workqueue: bat_events batadv_nc_worker
RIP: 0010:__rcu_read_unlock+0x0/0x580 kernel/rcu/tree_plugin.h:419
Code: e8 25 e1 4c 09 eb dd e8 de 2f 72 00 e9 4e ff ff ff 66 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 <f3> 0f 1e fa 41 56 41 55 41 54 55 65 48 8b 2d 9d 88 8f 7e 53 48 8d
RSP: 0018:ffffc90009d87ba0 EFLAGS: 00000206
RAX: 0000000000000000 RBX: 0000000000000001 RCX: ffffffff8a8800e8
RDX: ffff88802a51bb80 RSI: ffffffff8a87fda8 RDI: 0000000000000001
RBP: 00000000000001b2 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000002 R12: ffff888078439e00
R13: 0000000000000000 R14: dffffc0000000000 R15: 0000000000000001
FS:  0000000000000000(0000) GS:ffff8880b9400000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fa6e1ae1b90 CR3: 000000000d57a000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <NMI>
 </NMI>
 <TASK>
 rcu_read_unlock include/linux/rcupdate.h:782 [inline]
 batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:412 [inline]
 batadv_nc_worker+0x8e0/0x10f0 net/batman-adv/network-coding.c:719
 process_one_work+0x8d5/0x16e0 kernel/workqueue.c:2633
 process_scheduled_works kernel/workqueue.c:2707 [inline]
 worker_thread+0x8b6/0x1290 kernel/workqueue.c:2788
 kthread+0x2c1/0x3a0 kernel/kthread.c:388
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:242
 </TASK>