INFO: task syz.1.5798:27540 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.1.5798      state:D stack:26536 pid:27540 tgid:27539 ppid:17170  task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5260 [inline]
 __schedule+0x14ea/0x5050 kernel/sched/core.c:6867
 __schedule_loop kernel/sched/core.c:6949 [inline]
 schedule+0x164/0x360 kernel/sched/core.c:6964
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7021
 __mutex_lock_common kernel/locking/mutex.c:692 [inline]
 __mutex_lock+0x7fe/0x1300 kernel/locking/mutex.c:776
 nfsd_nl_version_get_doit+0x17c/0xc40 fs/nfsd/nfsctl.c:1811
 genl_family_rcv_msg_doit+0x22a/0x330 net/netlink/genetlink.c:1115
 genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline]
 genl_rcv_msg+0x61c/0x7a0 net/netlink/genetlink.c:1210
 netlink_rcv_skb+0x232/0x4b0 net/netlink/af_netlink.c:2550
 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1219
 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
 netlink_unicast+0x80f/0x9b0 net/netlink/af_netlink.c:1344
 netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1894
 sock_sendmsg_nosec net/socket.c:727 [inline]
 __sock_sendmsg net/socket.c:742 [inline]
 ____sys_sendmsg+0xa68/0xad0 net/socket.c:2592
 ___sys_sendmsg+0x2a5/0x360 net/socket.c:2646
 __sys_sendmsg net/socket.c:2678 [inline]
 __do_sys_sendmsg net/socket.c:2683 [inline]
 __se_sys_sendmsg net/socket.c:2681 [inline]
 __x64_sys_sendmsg+0x1bd/0x2a0 net/socket.c:2681
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xe2/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f035599aeb9
RSP: 002b:00007f0353bf6028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f0355c15fa0 RCX: 00007f035599aeb9
RDX: 0000000020044042 RSI: 0000200000000780 RDI: 0000000000000004
RBP: 00007f0355a08c1f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f0355c16038 R14: 00007f0355c15fa0 R15: 00007fff419f8998
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/31:
 #0: ffffffff8e55a360 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8e55a360 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline]
 #0: ffffffff8e55a360 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775
1 lock held by syslogd/5176:
 #0: ffff8880b873a918 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2a/0x140 kernel/sched/core.c:639
2 locks held by getty/5583:
 #0: ffff888034f800a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc900036bb2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45c/0x13c0 drivers/tty/n_tty.c:2211
2 locks held by syz.0.5791/27510:
 #0: ffffffff8fa1a230 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1218
 #1: ffffffff8e8793e8 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_listener_set_doit+0x141/0x16c0 fs/nfsd/nfsctl.c:1886
2 locks held by syz.1.5798/27540:
 #0: ffffffff8fa1a230 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1218
 #1: ffffffff8e8793e8 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_version_get_doit+0x17c/0xc40 fs/nfsd/nfsctl.c:1811
1 lock held by udevd/27789:
 #0: ffff888025eb8358 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xe0/0xd30 block/bdev.c:962
2 locks held by syz.2.6942/31847:
 #0: ffffffff8fa1a230 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1218
 #1: ffffffff8e8793e8 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_version_get_doit+0x17c/0xc40 fs/nfsd/nfsctl.c:1811
2 locks held by syz-executor/32482:
 #0: ffffffff8fa1a230 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1218
 #1: ffffffff8fa1a048 (genl_mutex){+.+.}-{4:4}, at: genl_lock net/netlink/genetlink.c:35 [inline]
 #1: ffffffff8fa1a048 (genl_mutex){+.+.}-{4:4}, at: genl_op_lock net/netlink/genetlink.c:60 [inline]
 #1: ffffffff8fa1a048 (genl_mutex){+.+.}-{4:4}, at: genl_rcv_msg+0x10b/0x7a0 net/netlink/genetlink.c:1209
6 locks held by syz.3.7158/32559:
 #0: ffffffff8fa1a230 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1218
 #1: ffffffff8fa1a048 (genl_mutex){+.+.}-{4:4}, at: genl_lock net/netlink/genetlink.c:35 [inline]
 #1: ffffffff8fa1a048 (genl_mutex){+.+.}-{4:4}, at: genl_op_lock net/netlink/genetlink.c:60 [inline]
 #1: ffffffff8fa1a048 (genl_mutex){+.+.}-{4:4}, at: genl_rcv_msg+0x10b/0x7a0 net/netlink/genetlink.c:1209
 #2: ffff888025ea9278 (&nbd->config_lock){+.+.}-{4:4}, at: nbd_genl_reconfigure+0x4c1/0x1ea0 drivers/block/nbd.c:2364
 #3: ffff888147ae9048 (&q->limits_lock){+.+.}-{4:4}, at: queue_limits_start_update include/linux/blkdev.h:1088 [inline]
 #3: ffff888147ae9048 (&q->limits_lock){+.+.}-{4:4}, at: nbd_set_size+0x2ba/0x6d0 drivers/block/nbd.c:354
 #4: ffff888147ae89e8 (&q->q_usage_counter(io)#52){++++}-{0:0}, at: blk_mq_freeze_queue include/linux/blk-mq.h:954 [inline]
 #4: ffff888147ae89e8 (&q->q_usage_counter(io)#52){++++}-{0:0}, at: queue_limits_commit_update_frozen+0x55/0xd0 block/blk-settings.c:603
 #5: ffff888147ae8a20 (&q->q_usage_counter(queue)#36){+.+.}-{0:0}, at: blk_mq_freeze_queue include/linux/blk-mq.h:954 [inline]
 #5: ffff888147ae8a20 (&q->q_usage_counter(queue)#36){+.+.}-{0:0}, at: queue_limits_commit_update_frozen+0x55/0xd0 block/blk-settings.c:603
2 locks held by syz.5.7160/32565:
 #0: ffffffff8fa1a230 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1218
 #1: ffffffff8fa1a048 (genl_mutex){+.+.}-{4:4}, at: genl_lock net/netlink/genetlink.c:35 [inline]
 #1: ffffffff8fa1a048 (genl_mutex){+.+.}-{4:4}, at: genl_op_lock net/netlink/genetlink.c:60 [inline]
 #1: ffffffff8fa1a048 (genl_mutex){+.+.}-{4:4}, at: genl_rcv_msg+0x10b/0x7a0 net/netlink/genetlink.c:1209
2 locks held by syz.5.7160/32574:
 #0: ffffffff8fa1a230 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1218
 #1: ffffffff8fa1a048 (genl_mutex){+.+.}-{4:4}, at: genl_lock net/netlink/genetlink.c:35 [inline]
 #1: ffffffff8fa1a048 (genl_mutex){+.+.}-{4:4}, at: genl_op_lock net/netlink/genetlink.c:60 [inline]
 #1: ffffffff8fa1a048 (genl_mutex){+.+.}-{4:4}, at: genl_rcv_msg+0x10b/0x7a0 net/netlink/genetlink.c:1209
2 locks held by syz.6.7161/32568:
 #0: ffffffff8fa1a230 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1218
 #1: ffffffff8fa1a048 (genl_mutex){+.+.}-{4:4}, at: genl_lock net/netlink/genetlink.c:35 [inline]
 #1: ffffffff8fa1a048 (genl_mutex){+.+.}-{4:4}, at: genl_op_lock net/netlink/genetlink.c:60 [inline]
 #1: ffffffff8fa1a048 (genl_mutex){+.+.}-{4:4}, at: genl_rcv_msg+0x10b/0x7a0 net/netlink/genetlink.c:1209
2 locks held by syz.4.7162/32580:
 #0: ffffffff8fa1a230 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1218
 #1: ffffffff8fa1a048 (genl_mutex){+.+.}-{4:4}, at: genl_lock net/netlink/genetlink.c:35 [inline]
 #1: ffffffff8fa1a048 (genl_mutex){+.+.}-{4:4}, at: genl_op_lock net/netlink/genetlink.c:60 [inline]
 #1: ffffffff8fa1a048 (genl_mutex){+.+.}-{4:4}, at: genl_rcv_msg+0x10b/0x7a0 net/netlink/genetlink.c:1209
2 locks held by syz.4.7162/32581:
 #0: ffffffff8fa1a230 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1218
 #1: ffffffff8fa1a048 (genl_mutex){+.+.}-{4:4}, at: genl_lock net/netlink/genetlink.c:35 [inline]
 #1: ffffffff8fa1a048 (genl_mutex){+.+.}-{4:4}, at: genl_op_lock net/netlink/genetlink.c:60 [inline]
 #1: ffffffff8fa1a048 (genl_mutex){+.+.}-{4:4}, at: genl_rcv_msg+0x10b/0x7a0 net/netlink/genetlink.c:1209
2 locks held by syz-executor/32589:
 #0: ffffffff8fa1a230 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1218
 #1: ffffffff8fa1a048 (genl_mutex){+.+.}-{4:4}, at: genl_lock net/netlink/genetlink.c:35 [inline]
 #1: ffffffff8fa1a048 (genl_mutex){+.+.}-{4:4}, at: genl_op_lock net/netlink/genetlink.c:60 [inline]
 #1: ffffffff8fa1a048 (genl_mutex){+.+.}-{4:4}, at: genl_rcv_msg+0x10b/0x7a0 net/netlink/genetlink.c:1209
2 locks held by syz-executor/32591:
 #0: ffffffff8fa1a230 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1218
 #1: ffffffff8fa1a048 (genl_mutex){+.+.}-{4:4}, at: genl_lock net/netlink/genetlink.c:35 [inline]
 #1: ffffffff8fa1a048 (genl_mutex){+.+.}-{4:4}, at: genl_op_lock net/netlink/genetlink.c:60 [inline]
 #1: ffffffff8fa1a048 (genl_mutex){+.+.}-{4:4}, at: genl_rcv_msg+0x10b/0x7a0 net/netlink/genetlink.c:1209
2 locks held by syz-executor/32592:
 #0: ffffffff8fa1a230 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1218
 #1: ffffffff8fa1a048 (genl_mutex){+.+.}-{4:4}, at: genl_lock net/netlink/genetlink.c:35 [inline]
 #1: ffffffff8fa1a048 (genl_mutex){+.+.}-{4:4}, at: genl_op_lock net/netlink/genetlink.c:60 [inline]
 #1: ffffffff8fa1a048 (genl_mutex){+.+.}-{4:4}, at: genl_rcv_msg+0x10b/0x7a0 net/netlink/genetlink.c:1209
8 locks held by syz-executor/32597:
 #0: ffff8880341ba420 (sb_writers#7){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2683 [inline]
 #0: ffff8880341ba420 (sb_writers#7){.+.+}-{0:0}, at: vfs_write+0x227/0xb90 fs/read_write.c:682
 #1: ffff88806a6e5088 (&of->mutex){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x1de/0x540 fs/kernfs/file.c:343
 #2: ffff88802843c0f8 (kn->active#52){.+.+}-{0:0}, at: kernfs_get_active_of fs/kernfs/file.c:80 [inline]
 #2: ffff88802843c0f8 (kn->active#52){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x231/0x540 fs/kernfs/file.c:344
 #3: ffffffff8f2225c8 (nsim_bus_dev_list_lock){+.+.}-{4:4}, at: del_device_store+0xd7/0x370 drivers/net/netdevsim/bus.c:234
 #4: ffff88803526d0e8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:895 [inline]
 #4: ffff88803526d0e8 (&dev->mutex){....}-{4:4}, at: __device_driver_lock drivers/base/dd.c:1106 [inline]
 #4: ffff88803526d0e8 (&dev->mutex){....}-{4:4}, at: device_release_driver_internal+0xb6/0x860 drivers/base/dd.c:1304
 #5: ffff888067d3d250 (&devlink->lock_key#7){+.+.}-{4:4}, at: nsim_drv_remove+0x50/0x170 drivers/net/netdevsim/dev.c:1778
 #6: ffffffff8f9ac188 (rtnl_mutex){+.+.}-{4:4}, at: nsim_destroy+0xed/0x680 drivers/net/netdevsim/netdev.c:1175
 #7: ffffffff8e560c78 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock kernel/rcu/tree_exp.h:343 [inline]
 #7: ffffffff8e560c78 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x38d/0x770 kernel/rcu/tree_exp.h:956

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

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 31 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x274/0x2d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x17a/0x300 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:161 [inline]
 __sys_info lib/sys_info.c:157 [inline]
 sys_info+0x135/0x170 lib/sys_info.c:165
 check_hung_uninterruptible_tasks kernel/hung_task.c:346 [inline]
 watchdog+0xf90/0xfe0 kernel/hung_task.c:515
 kthread+0x726/0x8b0 kernel/kthread.c:463
 ret_from_fork+0x51b/0xa40 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 32597 Comm: syz-executor Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
RIP: 0010:io_serial_in+0x77/0xc0 drivers/tty/serial/8250/8250_port.c:400
Code: e8 de b3 92 fc 44 89 f9 d3 e3 49 83 c6 40 4c 89 f0 48 c1 e8 03 42 80 3c 20 00 74 08 4c 89 f7 e8 7f 03 fb fc 41 03 1e 89 da ec <0f> b6 c0 5b 41 5c 41 5e 41 5f c3 cc cc cc cc cc 44 89 f9 80 e1 07
RSP: 0018:ffffc9000b82ea90 EFLAGS: 00000002
RAX: 1ffffffff3466c00 RBX: 00000000000003fd RCX: 0000000000000000
RDX: 00000000000003fd RSI: 0000000000000000 RDI: 0000000000000020
RBP: ffffffff9a336530 R08: ffff8881476e8237 R09: 1ffff11028edd046
R10: dffffc0000000000 R11: ffffffff8531c320 R12: dffffc0000000000
R13: 0000000000000000 R14: ffffffff9a3362a0 R15: 0000000000000000
FS:  000055556ae85500(0000) GS:ffff8881257f5000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055781e875ee8 CR3: 0000000048cca000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 serial_in drivers/tty/serial/8250/8250.h:128 [inline]
 serial_lsr_in drivers/tty/serial/8250/8250.h:150 [inline]
 wait_for_lsr+0x1a1/0x2f0 drivers/tty/serial/8250/8250_port.c:1961
 fifo_wait_for_lsr drivers/tty/serial/8250/8250_port.c:3234 [inline]
 serial8250_console_fifo_write drivers/tty/serial/8250/8250_port.c:3257 [inline]
 serial8250_console_write+0x1348/0x1ba0 drivers/tty/serial/8250/8250_port.c:3342
 console_emit_next_record kernel/printk/printk.c:3129 [inline]
 console_flush_one_record kernel/printk/printk.c:3215 [inline]
 console_flush_all+0x718/0xb20 kernel/printk/printk.c:3289
 __console_flush_and_unlock kernel/printk/printk.c:3319 [inline]
 console_unlock+0xd1/0x1c0 kernel/printk/printk.c:3359
 vprintk_emit+0x485/0x560 kernel/printk/printk.c:2426
 dev_vprintk_emit+0x355/0x420 drivers/base/core.c:4914
 dev_printk_emit+0xee/0x140 drivers/base/core.c:4925
 __netdev_printk+0x3e1/0x480 net/core/dev.c:12916
 netdev_info+0x11e/0x180 net/core/dev.c:12971
 nsim_udp_tunnel_unset_port+0x2d0/0x530 drivers/net/netdevsim/udp_tunnels.c:59
 udp_tunnel_nic_device_sync_one net/ipv4/udp_tunnel_nic.c:-1 [inline]
 udp_tunnel_nic_device_sync_by_port net/ipv4/udp_tunnel_nic.c:249 [inline]
 __udp_tunnel_nic_device_sync+0xb9f/0x1580 net/ipv4/udp_tunnel_nic.c:292
 udp_tunnel_nic_flush+0x2cc/0x670 net/ipv4/udp_tunnel_nic.c:694
 udp_tunnel_nic_unregister net/ipv4/udp_tunnel_nic.c:901 [inline]
 udp_tunnel_nic_netdevice_event+0xfb2/0x17d0 net/ipv4/udp_tunnel_nic.c:942
 notifier_call_chain+0x19d/0x3a0 kernel/notifier.c:85
 call_netdevice_notifiers_extack net/core/dev.c:2281 [inline]
 call_netdevice_notifiers net/core/dev.c:2295 [inline]
 unregister_netdevice_many_notify+0x186a/0x2370 net/core/dev.c:12396
 unregister_netdevice_many net/core/dev.c:12459 [inline]
 unregister_netdevice_queue+0x31f/0x360 net/core/dev.c:12273
 unregister_netdevice include/linux/netdevice.h:3405 [inline]
 nsim_destroy+0x1e5/0x680 drivers/net/netdevsim/netdev.c:1180
 __nsim_dev_port_del+0x14d/0x1b0 drivers/net/netdevsim/dev.c:1528
 nsim_dev_port_del_all drivers/net/netdevsim/dev.c:1540 [inline]
 nsim_dev_reload_destroy+0x288/0x490 drivers/net/netdevsim/dev.c:1764
 nsim_drv_remove+0x58/0x170 drivers/net/netdevsim/dev.c:1779
 device_remove drivers/base/dd.c:571 [inline]
 __device_release_driver drivers/base/dd.c:1284 [inline]
 device_release_driver_internal+0x46f/0x860 drivers/base/dd.c:1307
 bus_remove_device+0x34d/0x440 drivers/base/bus.c:616
 device_del+0x527/0x8f0 drivers/base/core.c:3878
 device_unregister+0x21/0xf0 drivers/base/core.c:3919
 nsim_bus_dev_del drivers/net/netdevsim/bus.c:491 [inline]
 del_device_store+0x2b0/0x370 drivers/net/netdevsim/bus.c:244
 kernfs_fop_write_iter+0x3af/0x540 fs/kernfs/file.c:352
 new_sync_write fs/read_write.c:593 [inline]
 vfs_write+0x61d/0xb90 fs/read_write.c:686
 ksys_write+0x150/0x270 fs/read_write.c:738
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xe2/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fba56b5b78e
Code: 08 0f 85 a5 a8 ff ff 49 89 fb 48 89 f0 48 89 d7 48 89 ce 4c 89 c2 4d 89 ca 4c 8b 44 24 08 4c 8b 4c 24 10 4c 89 5c 24 08 0f 05 <c3> 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 80 00 00 00 00 48 83 ec 08
RSP: 002b:00007fff2e1a5a48 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 000055556ae85500 RCX: 00007fba56b5b78e
RDX: 0000000000000001 RSI: 00007fff2e1a5ad0 RDI: 0000000000000005
RBP: 00007fba56c08a88 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007fff2e1a5ad0 R14: 00007fba57944620 R15: 0000000000000003
 </TASK>