INFO: task syz.0.3029:20042 blocked for more than 144 seconds.
      Tainted: G             L      syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.3029      state:D stack:26120 pid:20042 tgid:20041 ppid:18509  task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5510 [inline]
 __schedule+0x125c/0x6730 kernel/sched/core.c:7234
 __schedule_loop kernel/sched/core.c:7311 [inline]
 schedule+0xdd/0x2c0 kernel/sched/core.c:7326
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7383
 __mutex_lock_common kernel/locking/mutex.c:726 [inline]
 __mutex_lock+0xccc/0x1bd0 kernel/locking/mutex.c:821
 nfsd_nl_cache_flush_doit+0xd9/0x230 fs/nfsd/nfsctl.c:2236
 genl_family_rcv_msg_doit+0x214/0x300 net/netlink/genetlink.c:1114
 genl_family_rcv_msg net/netlink/genetlink.c:1194 [inline]
 genl_rcv_msg+0x560/0x800 net/netlink/genetlink.c:1209
 netlink_rcv_skb+0x159/0x420 net/netlink/af_netlink.c:2556
 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1218
 netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
 netlink_unicast+0x585/0x850 net/netlink/af_netlink.c:1345
 netlink_sendmsg+0x8b0/0xda0 net/netlink/af_netlink.c:1900
 sock_sendmsg_nosec net/socket.c:775 [inline]
 __sock_sendmsg net/socket.c:790 [inline]
 ____sys_sendmsg+0xa4d/0xbe0 net/socket.c:2684
 ___sys_sendmsg+0x190/0x1e0 net/socket.c:2738
 __sys_sendmsg+0x160/0x210 net/socket.c:2770
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f803a79e0d9
RSP: 002b:00007f803b678028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f803aa25fa0 RCX: 00007f803a79e0d9
RDX: 0000000004000080 RSI: 0000200000000100 RDI: 0000000000000005
RBP: 00007f803a835024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f803aa26038 R14: 00007f803aa25fa0 R15: 00007ffd05682c28
 </TASK>

Showing all locks held in the system:
3 locks held by kworker/0:1/10:
1 lock held by khungtaskd/30:
 #0: ffffffff8ebe8200 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
 #0: ffffffff8ebe8200 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:840 [inline]
 #0: ffffffff8ebe8200 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x3d/0x184 kernel/locking/lockdep.c:6775
3 locks held by kworker/u8:7/1003:
 #0: ffff88801bc44140 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x12b1/0x1940 kernel/workqueue.c:3297
 #1: ffffc90004d2fd08 ((linkwatch_work).work){+.+.}-{0:0}, at: process_one_work+0x988/0x1940 kernel/workqueue.c:3298
 #2: ffffffff90a99340 (rtnl_mutex){+.+.}-{4:4}, at: linkwatch_event+0x51/0xc0 net/core/link_watch.c:313
2 locks held by getty/5351:
 #0: ffff888037f670a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243
 #1: ffffc900032332e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x419/0x14e0 drivers/tty/n_tty.c:2211
4 locks held by udevd/5602:
 #0: ffff88802fdef098 (&p->lock){+.+.}-{4:4}, at: seq_read_iter+0xe1/0x1270 fs/seq_file.c:183
 #1: ffff88807a2c2080 (&of->mutex#2){+.+.}-{4:4}, at: kernfs_seq_start+0x4f/0x2a0 fs/kernfs/file.c:165
 #2: ffff88807469d2d8 (kn->active#31){++++}-{0:0}, at: kernfs_get_active_of fs/kernfs/file.c:73 [inline]
 #2: ffff88807469d2d8 (kn->active#31){++++}-{0:0}, at: kernfs_seq_start+0xbc/0x2a0 fs/kernfs/file.c:166
 #3: ffff888020b181d8 (&dev->mutex){....}-{4:4}, at: device_lock_interruptible include/linux/device.h:1109 [inline]
 #3: ffff888020b181d8 (&dev->mutex){....}-{4:4}, at: manufacturer_show+0x26/0xa0 drivers/usb/core/sysfs.c:142
4 locks held by kworker/0:4/5696:
 #0: ffff888020ee5540 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x12b1/0x1940 kernel/workqueue.c:3297
 #1: ffffc90004e07d08 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x988/0x1940 kernel/workqueue.c:3298
 #2: ffff88802b2ee1d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
 #2: ffff88802b2ee1d8 (&dev->mutex){....}-{4:4}, at: hub_event+0x1bb/0x4420 drivers/usb/core/hub.c:5907
 #3: ffff888020b181d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
 #3: ffff888020b181d8 (&dev->mutex){....}-{4:4}, at: __device_attach+0x7e/0x4d0 drivers/base/dd.c:1073
3 locks held by kworker/u8:13/9966:
 #0: ffff888034278140 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work+0x12b1/0x1940 kernel/workqueue.c:3297
 #1: ffffc90003677d08 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_one_work+0x988/0x1940 kernel/workqueue.c:3298
 #2: ffffffff90a99340 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
 #2: ffffffff90a99340 (rtnl_mutex){+.+.}-{4:4}, at: addrconf_dad_work+0x11f/0x1360 net/ipv6/addrconf.c:4229
3 locks held by kworker/0:10/13969:
 #0: ffff88801bc0b140 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x12b1/0x1940 kernel/workqueue.c:3297
 #1: ffffc90005937d08 (free_ipc_work){+.+.}-{0:0}, at: process_one_work+0x988/0x1940 kernel/workqueue.c:3298
 #2: ffffffff8ebf3ca8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock+0x19e/0x3c0 kernel/rcu/tree_exp.h:343
1 lock held by syz-executor/15569:
 #0: ffff88805e944ea0 (&hdev->req_lock){+.+.}-{4:4}, at: hci_dev_do_close+0x26/0xb0 net/bluetooth/hci_core.c:497
1 lock held by syz.5.2438/17444:
 #0: ffff888034d7cea0 (&hdev->req_lock){+.+.}-{4:4}, at: hci_dev_do_close+0x26/0xb0 net/bluetooth/hci_core.c:497
3 locks held by syz.8.2657/18310:
 #0: ffff8880363ad7b0 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x2aa/0x380 fs/file.c:1259
 #1: ffff88807857e450 (sb_writers#25){.+.+}-{0:0}, at: ksys_write+0x12a/0x250 fs/read_write.c:739
 #2: ffffffff8f0724c0 (nfsd_mutex){+.+.}-{4:4}, at: write_ports+0xa5/0xcc0 fs/nfsd/nfsctl.c:860
2 locks held by syz.0.3029/20042:
 #0: ffffffff90b48088 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217
 #1: ffffffff8f0724c0 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_cache_flush_doit+0xd9/0x230 fs/nfsd/nfsctl.c:2236
1 lock held by syz-executor/20222:
 #0: ffffffff90a99340 (rtnl_mutex){+.+.}-{4:4}, at: tun_detach drivers/net/tun.c:634 [inline]
 #0: ffffffff90a99340 (rtnl_mutex){+.+.}-{4:4}, at: tun_chr_close+0x38/0x220 drivers/net/tun.c:3442
1 lock held by dhcpcd/21895:
 #0: ffff88807506cd00 (&sb->s_type->i_mutex_key#13){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:1024 [inline]
 #0: ffff88807506cd00 (&sb->s_type->i_mutex_key#13){+.+.}-{4:4}, at: __sock_release+0x86/0x260 net/socket.c:709
1 lock held by syz-executor/21907:
 #0: ffff8880271f8ea0 (&hdev->req_lock){+.+.}-{4:4}, at: hci_dev_do_close+0x26/0xb0 net/bluetooth/hci_core.c:497
1 lock held by syz.6.3591/22332:
 #0: ffff88807397cea0 (&hdev->req_lock){+.+.}-{4:4}, at: hci_dev_do_close+0x26/0xb0 net/bluetooth/hci_core.c:497

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

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 30 Comm: khungtaskd Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
 nmi_cpu_backtrace.cold+0x12d/0x151 lib/nmi_backtrace.c:122
 nmi_trigger_cpumask_backtrace+0x21c/0x2a0 lib/nmi_backtrace.c:65
 trigger_all_cpu_backtrace include/linux/nmi.h:162 [inline]
 __sys_info lib/sys_info.c:157 [inline]
 sys_info+0x141/0x190 lib/sys_info.c:165
 check_hung_uninterruptible_tasks kernel/hung_task.c:353 [inline]
 watchdog+0xcb1/0x1030 kernel/hung_task.c:561
 kthread+0x370/0x450 kernel/kthread.c:436
 ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>