INFO: task syz.1.16221:8837 blocked for more than 143 seconds.
Tainted: G U I L syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.1.16221 state:D stack:29016 pid:8837 tgid:8836 ppid:5950 task_flags:0x400140 flags:0x00080002
Call Trace:
context_switch kernel/sched/core.c:5388 [inline]
__schedule+0x10e9/0x6820 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_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:576
nfsd_umount+0x3b/0x60 fs/nfsd/nfsctl.c:1364
deactivate_locked_super+0xc1/0x1b0 fs/super.c:476
deactivate_super fs/super.c:509 [inline]
deactivate_super+0xe7/0x110 fs/super.c:505
cleanup_mnt+0x21f/0x450 fs/namespace.c:1312
task_work_run+0x150/0x240 kernel/task_work.c:233
resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
__exit_to_user_mode_loop kernel/entry/common.c:67 [inline]
exit_to_user_mode_loop+0x100/0x4a0 kernel/entry/common.c:98
__exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:238 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:318 [inline]
do_syscall_64+0x6f2/0xf80 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f6cd4b9cdd9
RSP: 002b:00007f6cd599c028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: fffffffffffffffe RBX: 00007f6cd4e15fa0 RCX: 00007f6cd4b9cdd9
RDX: 0000200000000140 RSI: 00002000000000c0 RDI: 0000000000000000
RBP: 00007f6cd4c32d69 R08: 0000000000000000 R09: 0000000000000000
R10: 000000000000000f R11: 0000000000000246 R12: 0000000000000000
R13: 00007f6cd4e16038 R14: 00007f6cd4e15fa0 R15: 00007ffdbb209688
Showing all locks held in the system:
1 lock held by khungtaskd/30:
#0: ffffffff8e7e52e0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
#0: ffffffff8e7e52e0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline]
#0: ffffffff8e7e52e0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x3d/0x184 kernel/locking/lockdep.c:6775
2 locks held by kworker/u10:2/17130:
#0: ffff88801efc4940 ((wq_completion)iou_exit){+.+.}-{0:0}, at: process_one_work+0x12d6/0x1980 kernel/workqueue.c:3277
#1: ffffc900037d7d08 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x973/0x1980 kernel/workqueue.c:3278
2 locks held by getty/30564:
#0: ffff888037e190a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243
#1: ffffc900025b72e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x419/0x14f0 drivers/tty/n_tty.c:2211
2 locks held by syz.0.12577/31916:
#0: ffff888077bde0d8 (&type->s_umount_key#57){++++}-{4:4}, at: __super_lock fs/super.c:58 [inline]
#0: ffff888077bde0d8 (&type->s_umount_key#57){++++}-{4:4}, at: __super_lock_excl fs/super.c:73 [inline]
#0: ffff888077bde0d8 (&type->s_umount_key#57){++++}-{4:4}, at: deactivate_super fs/super.c:508 [inline]
#0: ffff888077bde0d8 (&type->s_umount_key#57){++++}-{4:4}, at: deactivate_super+0xdf/0x110 fs/super.c:505
#1: ffffffff8ec61b60 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:576
3 locks held by kworker/0:4/7031:
#0: ffff88813fe57140 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x12d6/0x1980 kernel/workqueue.c:3277
#1: ffffc90005697d08 (free_ipc_work){+.+.}-{0:0}, at: process_one_work+0x973/0x1980 kernel/workqueue.c:3278
#2: ffffffff8e7f0e28 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock+0x19e/0x3c0 kernel/rcu/tree_exp.h:343
3 locks held by kworker/0:7/7032:
#0: ffff88813fe57140 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x12d6/0x1980 kernel/workqueue.c:3277
#1: ffffc9000549fd08 (xfrm_state_gc_work){+.+.}-{0:0}, at: process_one_work+0x973/0x1980 kernel/workqueue.c:3278
#2: ffffffff8e7f0e28 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock+0x27f/0x3c0 kernel/rcu/tree_exp.h:311
2 locks held by syz.3.16136/8565:
#0: ffffffff906bc948 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217
#1: ffffffff8ec61b60 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_listener_set_doit+0xd5/0x1a80 fs/nfsd/nfsctl.c:1938
2 locks held by syz-executor/8724:
#0: ffff88803715a0d8 (&type->s_umount_key#57){++++}-{4:4}, at: __super_lock fs/super.c:58 [inline]
#0: ffff88803715a0d8 (&type->s_umount_key#57){++++}-{4:4}, at: __super_lock_excl fs/super.c:73 [inline]
#0: ffff88803715a0d8 (&type->s_umount_key#57){++++}-{4:4}, at: deactivate_super fs/super.c:508 [inline]
#0: ffff88803715a0d8 (&type->s_umount_key#57){++++}-{4:4}, at: deactivate_super+0xdf/0x110 fs/super.c:505
#1: ffffffff8ec61b60 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:576
2 locks held by syz.1.16221/8837:
#0: ffff88806ad040d8 (&type->s_umount_key#57){++++}-{4:4}, at: __super_lock fs/super.c:58 [inline]
#0: ffff88806ad040d8 (&type->s_umount_key#57){++++}-{4:4}, at: __super_lock_excl fs/super.c:73 [inline]
#0: ffff88806ad040d8 (&type->s_umount_key#57){++++}-{4:4}, at: deactivate_super fs/super.c:508 [inline]
#0: ffff88806ad040d8 (&type->s_umount_key#57){++++}-{4:4}, at: deactivate_super+0xdf/0x110 fs/super.c:505
#1: ffffffff8ec61b60 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:576
2 locks held by syz.5.16461/9585:
#0: ffffffff906bc948 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217
#1: ffffffff8ec61b60 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_threads_set_doit+0x8ec/0x12b0 fs/nfsd/nfsctl.c:1633
1 lock held by syz-executor/10047:
1 lock held by syz.2.16992/11320:
4 locks held by syz.6.17018/11390:
#0: ffff888053a14ea0 (&hdev->req_lock){+.+.}-{4:4}, at: hci_dev_do_close+0x26/0xb0 net/bluetooth/hci_core.c:500
#1: ffff888053a140b8 (&hdev->lock){+.+.}-{4:4}, at: hci_dev_close_sync+0x35c/0x1240 net/bluetooth/hci_sync.c:5356
#2: ffffffff90894740 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_disconn_cfm include/net/bluetooth/hci_core.h:2151 [inline]
#2: ffffffff90894740 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_conn_hash_flush+0xbb/0x280 net/bluetooth/hci_conn.c:2650
#3: ffff888035a6aaf8 (&conn->lock#2){+.+.}-{4:4}, at: l2cap_conn_del+0x95/0x710 net/bluetooth/l2cap_core.c:1777
2 locks held by syz.7.17022/11404:
=============================================
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 30 Comm: khungtaskd Tainted: G U I L syzkaller #0 PREEMPT(full)
Tainted: [U]=USER, [I]=FIRMWARE_WORKAROUND, [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