INFO: task syz.1.1560:9153 blocked for more than 144 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.1.1560      state:D stack:28560 pid:9153  ppid:4283   flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5246 [inline]
 __schedule+0x107f/0x4030 kernel/sched/core.c:6563
 schedule+0xb9/0x180 kernel/sched/core.c:6639
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6698
 __mutex_lock_common kernel/locking/mutex.c:679 [inline]
 __mutex_lock+0x548/0xae0 kernel/locking/mutex.c:747
 nfsd_shutdown_threads+0x4f/0x1a0 fs/nfsd/nfssvc.c:633
 nfsd_umount+0x3e/0xc0 fs/nfsd/nfsctl.c:1409
 deactivate_locked_super+0x93/0xf0 fs/super.c:332
 cleanup_mnt+0x471/0x4f0 fs/namespace.c:1191
 task_work_run+0x1d0/0x260 kernel/task_work.c:203
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 exit_to_user_mode_loop+0xe6/0x110 kernel/entry/common.c:177
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
 syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:303
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fcaf5d9e0d9
RSP: 002b:00007fcaf6cd8028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffea RBX: 00007fcaf6025fa0 RCX: 00007fcaf5d9e0d9
RDX: 0000200000000100 RSI: 00002000000000c0 RDI: 0000000000000000
RBP: 00007fcaf5e35024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fcaf6026038 R14: 00007fcaf6025fa0 R15: 00007ffd8420ca08
 </TASK>

Showing all locks held in the system:
1 lock held by rcu_tasks_kthre/12:
 #0: ffffffff8cb2e4f0 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x33/0xef0 kernel/rcu/tasks.h:517
1 lock held by rcu_tasks_trace/13:
 #0: ffffffff8cb2ed10 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x33/0xef0 kernel/rcu/tasks.h:517
1 lock held by khungtaskd/27:
 #0: ffffffff8cb2db60 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 #0: ffffffff8cb2db60 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
 #0: ffffffff8cb2db60 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x51/0x290 kernel/locking/lockdep.c:6527
4 locks held by klogd/3626:
 #0: ffff8880b8e3ad18 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x25/0x130 kernel/sched/core.c:538
 #1: ffff8880b8e27888 (&per_cpu_ptr(group->pcpu, cpu)->seq){-.-.}-{0:0}, at: psi_task_switch+0x36b/0x740 kernel/sched/psi.c:987
 #2: ffff88807d2dc618 (&p->pi_lock){-.-.}-{2:2}, at: try_to_wake_up+0x5a/0x10b0 kernel/sched/core.c:4112
 #3: ffff8880b8f3ad18 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x25/0x130 kernel/sched/core.c:538
2 locks held by getty/4022:
 #0: ffff88802f5c7098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:244
 #1: ffffc9000327b2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x41e/0x1360 drivers/tty/n_tty.c:2198
3 locks held by syz.2.1475/8779:
 #0: ffff88807f5d0368 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x2ae/0x360 fs/file.c:1038
 #1: ffff888054d54460 (sb_writers#20){.+.+}-{0:0}, at: vfs_write+0x270/0x9a0 fs/read_write.c:580
 #2: ffffffff8cdccde8 (nfsd_mutex){+.+.}-{3:3}, at: write_ports+0xb3/0xb80 fs/nfsd/nfsctl.c:846
2 locks held by syz.1.1560/9153:
 #0: ffff88804bc5a0e0 (&type->s_umount_key#75){+.+.}-{3:3}, at: deactivate_super+0xa0/0xd0 fs/super.c:362
 #1: ffffffff8cdccde8 (nfsd_mutex){+.+.}-{3:3}, at: nfsd_shutdown_threads+0x4f/0x1a0 fs/nfsd/nfssvc.c:633
2 locks held by rm/10989:

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

NMI backtrace for cpu 1
CPU: 1 PID: 27 Comm: khungtaskd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x24e lib/dump_stack.c:106
 nmi_cpu_backtrace+0x3e6/0x460 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x1d4/0x450 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:220 [inline]
 watchdog+0xf0e/0xf50 kernel/hung_task.c:377
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0 skipped: idling at native_safe_halt arch/x86/include/asm/irqflags.h:51 [inline]
NMI backtrace for cpu 0 skipped: idling at arch_safe_halt arch/x86/include/asm/irqflags.h:89 [inline]
NMI backtrace for cpu 0 skipped: idling at default_idle+0xb/0x10 arch/x86/kernel/process.c:741