INFO: task syz.2.3950:18967 blocked for more than 143 seconds.
Tainted: G U L syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.2.3950 state:D stack:28136 pid:18967 tgid:18963 ppid:16541 task_flags:0x400140 flags:0x00080002
Call Trace:
context_switch kernel/sched/core.c:5388 [inline]
__schedule+0x1295/0x67a0 kernel/sched/core.c:7189
__schedule_loop kernel/sched/core.c:7268 [inline]
schedule+0xdd/0x390 kernel/sched/core.c:7283
schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7340
__mutex_lock_common kernel/locking/mutex.c:726 [inline]
__mutex_lock+0xced/0x1b10 kernel/locking/mutex.c:820
nfsd_nl_listener_get_doit+0x13e/0x7b0 fs/nfsd/nfsctl.c:2088
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:2550
genl_rcv+0x28/0x40 net/netlink/genetlink.c:1218
netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
netlink_unicast+0x585/0x850 net/netlink/af_netlink.c:1344
netlink_sendmsg+0x8b0/0xda0 net/netlink/af_netlink.c:1894
sock_sendmsg_nosec net/socket.c:787 [inline]
__sock_sendmsg net/socket.c:802 [inline]
____sys_sendmsg+0x9e1/0xb70 net/socket.c:2698
___sys_sendmsg+0x190/0x1e0 net/socket.c:2752
__sys_sendmsg+0x170/0x220 net/socket.c:2784
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x10b/0x830 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb2fc99ce59
RSP: 002b:00007fb2fd8ee028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fb2fcc16090 RCX: 00007fb2fc99ce59
RDX: 0000000020010090 RSI: 0000200000000380 RDI: 0000000000000003
RBP: 00007fb2fca32d6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fb2fcc16128 R14: 00007fb2fcc16090 R15: 00007ffdf4f91b68
Showing all locks held in the system:
1 lock held by khungtaskd/31:
#0: ffffffff8e7e5420 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
#0: ffffffff8e7e5420 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline]
#0: ffffffff8e7e5420 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x3d/0x184 kernel/locking/lockdep.c:6775
2 locks held by syz-executor/17838:
#0: ffff88802d4840d8 (&type->s_umount_key#52){+.+.}-{4:4}, at: __super_lock fs/super.c:58 [inline]
#0: ffff88802d4840d8 (&type->s_umount_key#52){+.+.}-{4:4}, at: __super_lock_excl fs/super.c:73 [inline]
#0: ffff88802d4840d8 (&type->s_umount_key#52){+.+.}-{4:4}, at: deactivate_super fs/super.c:508 [inline]
#0: ffff88802d4840d8 (&type->s_umount_key#52){+.+.}-{4:4}, at: deactivate_super+0xdf/0x110 fs/super.c:505
#1: ffffffff8ec62380 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:576
2 locks held by syz.2.3950/18964:
#0: ffffffff906bfe08 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217
#1: ffffffff8ec62380 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_threads_set_doit+0x8ec/0x12b0 fs/nfsd/nfsctl.c:1633
2 locks held by syz.2.3950/18967:
#0: ffffffff906bfe08 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217
#1: ffffffff8ec62380 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_listener_get_doit+0x13e/0x7b0 fs/nfsd/nfsctl.c:2088
2 locks held by syz-executor/19199:
#0: ffffffff906118e0 (rtnl_mutex){+.+.}-{4:4}, at: tun_detach drivers/net/tun.c:634 [inline]
#0: ffffffff906118e0 (rtnl_mutex){+.+.}-{4:4}, at: tun_chr_close+0x38/0x220 drivers/net/tun.c:3438
#1: ffffffff8e7f0f68 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock+0x19e/0x3c0 kernel/rcu/tree_exp.h:343
2 locks held by syz.1.4063/19510:
#0: ffff88807fdea0d8 (&type->s_umount_key#52){+.+.}-{4:4}, at: __super_lock fs/super.c:58 [inline]
#0: ffff88807fdea0d8 (&type->s_umount_key#52){+.+.}-{4:4}, at: __super_lock_excl fs/super.c:73 [inline]
#0: ffff88807fdea0d8 (&type->s_umount_key#52){+.+.}-{4:4}, at: deactivate_super fs/super.c:508 [inline]
#0: ffff88807fdea0d8 (&type->s_umount_key#52){+.+.}-{4:4}, at: deactivate_super+0xdf/0x110 fs/super.c:505
#1: ffffffff8ec62380 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:576
2 locks held by syz-executor/19786:
#0: ffff88807f1b20d8 (&type->s_umount_key#52){+.+.}-{4:4}, at: __super_lock fs/super.c:58 [inline]
#0: ffff88807f1b20d8 (&type->s_umount_key#52){+.+.}-{4:4}, at: __super_lock_excl fs/super.c:73 [inline]
#0: ffff88807f1b20d8 (&type->s_umount_key#52){+.+.}-{4:4}, at: deactivate_super fs/super.c:508 [inline]
#0: ffff88807f1b20d8 (&type->s_umount_key#52){+.+.}-{4:4}, at: deactivate_super+0xdf/0x110 fs/super.c:505
#1: ffffffff8ec62380 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:576
2 locks held by syz-executor/20784:
#0: ffff888022b780d8 (&type->s_umount_key#52){+.+.}-{4:4}, at: __super_lock fs/super.c:58 [inline]
#0: ffff888022b780d8 (&type->s_umount_key#52){+.+.}-{4:4}, at: __super_lock_excl fs/super.c:73 [inline]
#0: ffff888022b780d8 (&type->s_umount_key#52){+.+.}-{4:4}, at: deactivate_super fs/super.c:508 [inline]
#0: ffff888022b780d8 (&type->s_umount_key#52){+.+.}-{4:4}, at: deactivate_super+0xdf/0x110 fs/super.c:505
#1: ffffffff8ec62380 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:576
5 locks held by syz-executor/21451:
#0: ffff888094f90ea0 (&hdev->req_lock){+.+.}-{4:4}, at: hci_dev_do_close+0x26/0xb0 net/bluetooth/hci_core.c:500
#1: ffff888094f900b8 (&hdev->lock){+.+.}-{4:4}, at: hci_dev_close_sync+0x35c/0x1240 net/bluetooth/hci_sync.c:5359
#2: ffffffff908986c0 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_disconn_cfm include/net/bluetooth/hci_core.h:2151 [inline]
#2: ffffffff908986c0 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_conn_hash_flush+0xbb/0x280 net/bluetooth/hci_conn.c:2734
#3: ffff8880415392f8 (&conn->lock#2){+.+.}-{4:4}, at: l2cap_conn_del+0x95/0x710 net/bluetooth/l2cap_core.c:1777
#4: ffffffff8e7f0f68 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock+0x27f/0x3c0 kernel/rcu/tree_exp.h:311
2 locks held by syz.3.4447/21680:
#0: ffff888085c900d8 (&type->s_umount_key#52){+.+.}-{4:4}, at: __super_lock fs/super.c:58 [inline]
#0: ffff888085c900d8 (&type->s_umount_key#52){+.+.}-{4:4}, at: __super_lock_excl fs/super.c:73 [inline]
#0: ffff888085c900d8 (&type->s_umount_key#52){+.+.}-{4:4}, at: deactivate_super fs/super.c:508 [inline]
#0: ffff888085c900d8 (&type->s_umount_key#52){+.+.}-{4:4}, at: deactivate_super+0xdf/0x110 fs/super.c:505
#1: ffffffff8ec62380 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:576
3 locks held by syz-executor/21683:
#0: ffff888044da8ea0 (&hdev->req_lock){+.+.}-{4:4}, at: hci_dev_do_close+0x26/0xb0 net/bluetooth/hci_core.c:500
#1: ffff888044da80b8 (&hdev->lock){+.+.}-{4:4}, at: hci_dev_close_sync+0x35c/0x1240 net/bluetooth/hci_sync.c:5359
#2: ffffffff908986c0 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_disconn_cfm include/net/bluetooth/hci_core.h:2151 [inline]
#2: ffffffff908986c0 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_conn_hash_flush+0xbb/0x280 net/bluetooth/hci_conn.c:2734
=============================================
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 31 Comm: khungtaskd Tainted: G U L syzkaller #0 PREEMPT(full)
Tainted: [U]=USER, [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Call Trace:
__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:113
nmi_trigger_cpumask_backtrace+0x1d7/0x230 lib/nmi_backtrace.c:62
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