INFO: task syz-executor:27155 blocked for more than 143 seconds.
Tainted: G U 6.15.0-rc6-syzkaller-00085-gc94d59a126cb #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor state:D stack:24200 pid:27155 tgid:27155 ppid:1 task_flags:0x400140 flags:0x00004004
Call Trace:
context_switch kernel/sched/core.c:5382 [inline]
__schedule+0x116f/0x5de0 kernel/sched/core.c:6767
__schedule_loop kernel/sched/core.c:6845 [inline]
schedule+0xe7/0x3a0 kernel/sched/core.c:6860
schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:6917
__mutex_lock_common kernel/locking/mutex.c:678 [inline]
__mutex_lock+0x6c7/0xb90 kernel/locking/mutex.c:746
nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:596
nfsd_umount+0x48/0xe0 fs/nfsd/nfsctl.c:1386
deactivate_locked_super+0xc1/0x1a0 fs/super.c:473
deactivate_super fs/super.c:506 [inline]
deactivate_super+0xde/0x100 fs/super.c:502
cleanup_mnt+0x225/0x450 fs/namespace.c:1431
task_work_run+0x14d/0x240 kernel/task_work.c:227
resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
exit_to_user_mode_loop kernel/entry/common.c:114 [inline]
exit_to_user_mode_prepare include/linux/entry-common.h:329 [inline]
__syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
syscall_exit_to_user_mode+0x27b/0x2a0 kernel/entry/common.c:218
do_syscall_64+0xda/0x230 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7efdbbf8fc97
RSP: 002b:00007ffdd687bcc8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007efdbc01089d RCX: 00007efdbbf8fc97
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffdd687bd80
RBP: 00007ffdd687bd80 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000ffffffff R11: 0000000000000246 R12: 00007ffdd687ce10
R13: 00007efdbc01089d R14: 00000000001cbec0 R15: 00007ffdd687ce50
Showing all locks held in the system:
1 lock held by khungtaskd/31:
#0: ffffffff8e3bfa80 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
#0: ffffffff8e3bfa80 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
#0: ffffffff8e3bfa80 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x36/0x1c0 kernel/locking/lockdep.c:6764
2 locks held by kworker/u9:1/5141:
#0: ffff888025cf9948 ((wq_completion)nbd0-recv){+.+.}-{0:0}, at: process_one_work+0x12a2/0x1b70 kernel/workqueue.c:3213
#1: ffffc9000ec4fd18 ((work_completion)(&args->work)){+.+.}-{0:0}, at: process_one_work+0x929/0x1b70 kernel/workqueue.c:3214
2 locks held by syz-executor/16417:
#0: ffff88804464c0e0 (&type->s_umount_key#50){+.+.}-{4:4}, at: __super_lock fs/super.c:56 [inline]
#0: ffff88804464c0e0 (&type->s_umount_key#50){+.+.}-{4:4}, at: __super_lock_excl fs/super.c:71 [inline]
#0: ffff88804464c0e0 (&type->s_umount_key#50){+.+.}-{4:4}, at: deactivate_super fs/super.c:505 [inline]
#0: ffff88804464c0e0 (&type->s_umount_key#50){+.+.}-{4:4}, at: deactivate_super+0xd6/0x100 fs/super.c:502
#1: ffffffff8e7cc728 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:596
2 locks held by kworker/u9:2/19100:
#0: ffff888025e68148 ((wq_completion)nbd2-recv){+.+.}-{0:0}, at: process_one_work+0x12a2/0x1b70 kernel/workqueue.c:3213
#1: ffffc9000b0c7d18 ((work_completion)(&args->work)){+.+.}-{0:0}, at: process_one_work+0x929/0x1b70 kernel/workqueue.c:3214
2 locks held by syz.4.7409/26974:
#0: ffffffff901c97d0 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1218
#1: ffffffff8e7cc728 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_threads_set_doit+0x698/0xbf0 fs/nfsd/nfsctl.c:1629
2 locks held by syz-executor/27155:
#0: ffff88805db3e0e0 (&type->s_umount_key#50){+.+.}-{4:4}, at: __super_lock fs/super.c:56 [inline]
#0: ffff88805db3e0e0 (&type->s_umount_key#50){+.+.}-{4:4}, at: __super_lock_excl fs/super.c:71 [inline]
#0: ffff88805db3e0e0 (&type->s_umount_key#50){+.+.}-{4:4}, at: deactivate_super fs/super.c:505 [inline]
#0: ffff88805db3e0e0 (&type->s_umount_key#50){+.+.}-{4:4}, at: deactivate_super+0xd6/0x100 fs/super.c:502
#1: ffffffff8e7cc728 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:596
2 locks held by getty/27485:
#0: ffff88803524a0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243
#1: ffffc90003ea32f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x41b/0x14f0 drivers/tty/n_tty.c:2222
=============================================
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 31 Comm: khungtaskd Tainted: G U 6.15.0-rc6-syzkaller-00085-gc94d59a126cb #0 PREEMPT(full)
Tainted: [U]=USER
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
nmi_cpu_backtrace+0x27b/0x390 lib/nmi_backtrace.c:113
nmi_trigger_cpumask_backtrace+0x29c/0x300 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:158 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:274 [inline]
watchdog+0xf70/0x12c0 kernel/hung_task.c:437
kthread+0x3c5/0x780 kernel/kthread.c:464
ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:153
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245