INFO: task syz-executor.0:5509 blocked for more than 143 seconds.
      Not tainted 6.9.0-rc5-syzkaller-00031-g71b1543c83d6 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor.0  state:D
 stack:26776 pid:5509  tgid:5502  ppid:5444   flags:0x00004006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5409 [inline]
 __schedule+0x17e8/0x4a50 kernel/sched/core.c:6746
 __schedule_loop kernel/sched/core.c:6823 [inline]
 schedule+0x14b/0x320 kernel/sched/core.c:6838
 schedule_timeout+0xb0/0x310 kernel/time/timer.c:2558
 do_wait_for_common kernel/sched/completion.c:95 [inline]
 __wait_for_common kernel/sched/completion.c:116 [inline]
 wait_for_common kernel/sched/completion.c:127 [inline]
 wait_for_completion+0x355/0x620 kernel/sched/completion.c:148
 __flush_workqueue+0x7d6/0x1710 kernel/workqueue.c:3994
 nbd_start_device_ioctl drivers/block/nbd.c:1463 [inline]
 __nbd_ioctl drivers/block/nbd.c:1524 [inline]
 nbd_ioctl+0xbd1/0xf40 drivers/block/nbd.c:1564
 blkdev_ioctl+0x5e7/0x740 block/ioctl.c:642
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:904 [inline]
 __se_sys_ioctl+0xfe/0x170 fs/ioctl.c:890
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f1ec8e7cae9
RSP: 002b:00007f1ec9c9b0c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f1ec8f9c050 RCX: 00007f1ec8e7cae9
RDX: 0000000000000000 RSI: 000000000000ab03 RDI: 0000000000000003
RBP: 00007f1ec8ec847a R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000006e R14: 00007f1ec8f9c050 R15: 00007ffc63144628
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/29:
 #0: ffffffff8e334d20 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:329 [inline]
 #0: ffffffff8e334d20 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:781 [inline]
 #0: ffffffff8e334d20 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x55/0x2a0 kernel/locking/lockdep.c:6614
2 locks held by kworker/u8:5/141:
 #0: ffff8880b943e698 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2a/0x140 kernel/sched/core.c:559
 #1: ffff8880b9428948 (&per_cpu_ptr(group->pcpu, cpu)->seq){-.-.}-{0:0}, at: psi_task_switch+0x3a7/0x770 kernel/sched/psi.c:976
2 locks held by getty/4840:
 #0: ffff88802a5470a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc900031332f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x6b5/0x1e10 drivers/tty/n_tty.c:2201
2 locks held by kworker/u9:2/5089:
 #0: ffff888020228948 ((wq_completion)nbd0-recv){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3229 [inline]
 #0: ffff888020228948 ((wq_completion)nbd0-recv){+.+.}-{0:0}, at: process_scheduled_works+0x8e0/0x17c0 kernel/workqueue.c:3335
 #1: ffffc90004d9fd00 ((work_completion)(&args->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3230 [inline]
 #1: ffffc90004d9fd00 ((work_completion)(&args->work)){+.+.}-{0:0}, at: process_scheduled_works+0x91b/0x17c0 kernel/workqueue.c:3335
1 lock held by syz-executor.0/9282:
 #0: ffff888020194998 (&nbd->config_lock){+.+.}-{3:3}, at: nbd_ioctl+0x13c/0xf40 drivers/block/nbd.c:1557
1 lock held by syz-executor.0/9283:
 #0: ffff888020194998 (&nbd->config_lock){+.+.}-{3:3}, at: nbd_ioctl+0x13c/0xf40 drivers/block/nbd.c:1557

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

NMI backtrace for cpu 0
CPU: 0 PID: 29 Comm: khungtaskd Not tainted 6.9.0-rc5-syzkaller-00031-g71b1543c83d6 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
 nmi_cpu_backtrace+0x49c/0x4d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x198/0x320 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:223 [inline]
 watchdog+0xfde/0x1020 kernel/hung_task.c:380
 kthread+0x2f2/0x390 kernel/kthread.c:388
 ret_from_fork+0x4d/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 4516 Comm: syslogd Not tainted 6.9.0-rc5-syzkaller-00031-g71b1543c83d6 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
RIP: 0010:unwind_next_frame+0xc4/0x2a00 arch/x86/kernel/unwind_orc.c:482
Code: 89 f6 e8 8f c5 54 00 44 89 b4 24 8c 00 00 00 45 85 f6 0f 84 8a 00 00 00 48 89 5c 24 50 bf 01 00 00 00 e8 7f 65 24 00 4c 89 e9 <4c> 8d 6d 50 4c 89 e8 48 c1 e8 03 48 89 44 24 40 80 3c 08 00 74 08
RSP: 0018:ffffc900034af300 EFLAGS: 00000246
RAX: 1ffff1100ffed298 RBX: ffffc900034af478 RCX: dffffc0000000000
RDX: ffff88807ff68000 RSI: 0000000000000001 RDI: ffffffff81414031
RBP: ffffc900034af440 R08: ffffffff81414011 R09: ffffc900034af440
R10: dffffc0000000000 R11: fffff52000695e94 R12: ffffc900034af4d8
R13: dffffc0000000000 R14: 0000000000000001 R15: ffffffff814171ec
FS:  00007f449a5e9380(0000) GS:ffff8880b9500000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f51f6524d58 CR3: 000000002b8a2000 CR4: 0000000000350ef0
Call Trace:
 <NMI>
 </NMI>
 <TASK>
 __unwind_start+0x641/0x7c0 arch/x86/kernel/unwind_orc.c:760
 unwind_start arch/x86/include/asm/unwind.h:64 [inline]
 arch_stack_walk+0x103/0x1b0 arch/x86/kernel/stacktrace.c:24
 stack_trace_save+0x118/0x1d0 kernel/stacktrace.c:122
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
 kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:579
 poison_slab_object+0xa6/0xe0 mm/kasan/common.c:240
 __kasan_slab_free+0x37/0x60 mm/kasan/common.c:256
 kasan_slab_free include/linux/kasan.h:184 [inline]
 slab_free_hook mm/slub.c:2106 [inline]
 slab_free mm/slub.c:4280 [inline]
 kfree+0x153/0x3a0 mm/slub.c:4390
 skb_kfree_head net/core/skbuff.c:1096 [inline]
 skb_free_head net/core/skbuff.c:1108 [inline]
 skb_release_data+0x585/0x870 net/core/skbuff.c:1136
 skb_release_all net/core/skbuff.c:1202 [inline]
 __kfree_skb net/core/skbuff.c:1216 [inline]
 consume_skb+0xb3/0x160 net/core/skbuff.c:1432
 __unix_dgram_recvmsg+0xe2d/0x1450 net/unix/af_unix.c:2514
 sock_recvmsg_nosec net/socket.c:1046 [inline]
 sock_recvmsg+0x231/0x280 net/socket.c:1068
 sock_read_iter+0x2ca/0x3e0 net/socket.c:1138
 call_read_iter include/linux/fs.h:2104 [inline]
 new_sync_read fs/read_write.c:395 [inline]
 vfs_read+0x97d/0xb70 fs/read_write.c:476
 ksys_read+0x1a0/0x2c0 fs/read_write.c:619
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f449a73db6a
Code: 00 3d 00 00 41 00 75 0d 50 48 8d 3d 2d 08 0a 00 e8 ea 7d 01 00 31 c0 e9 07 ff ff ff 64 8b 04 25 18 00 00 00 85 c0 75 1b 0f 05 <48> 3d 00 f0 ff ff 76 6c 48 8b 15 8f a2 0d 00 f7 d8 64 89 02 48 83
RSP: 002b:00007ffd5e27fe78 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 00007f449a73db6a
RDX: 00000000000000ff RSI: 0000562721df8950 RDI: 0000000000000000
RBP: 0000562721df8910 R08: 0000000000000001 R09: 0000000000000000
R10: 00007f449a8dc3a3 R11: 0000000000000246 R12: 0000562721df89a1
R13: 0000562721df8950 R14: 0000000000000000 R15: 00007f449a920a80
 </TASK>