INFO: task syz.6.3032:16286 blocked for more than 143 seconds.
      Not tainted 6.16.0-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.6.3032      state:D stack:26472 pid:16286 tgid:16284 ppid:9906   task_flags:0x400140 flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5397 [inline]
 __schedule+0x16aa/0x4c90 kernel/sched/core.c:6786
 __schedule_loop kernel/sched/core.c:6864 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:6879
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:6936
 __mutex_lock_common kernel/locking/mutex.c:679 [inline]
 __mutex_lock+0x724/0xe80 kernel/locking/mutex.c:747
 nfsd_shutdown_threads+0x4e/0xd0 fs/nfsd/nfssvc.c:596
 nfsd_umount+0x42/0xd0 fs/nfsd/nfsctl.c:1386
 deactivate_locked_super+0xbc/0x130 fs/super.c:474
 cleanup_mnt+0x425/0x4c0 fs/namespace.c:1417
 task_work_run+0x1d1/0x260 kernel/task_work.c:227
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 exit_to_user_mode_loop+0xec/0x110 kernel/entry/common.c:114
 exit_to_user_mode_prepare include/linux/entry-common.h:330 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:414 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:449 [inline]
 do_syscall_64+0x2bd/0x3b0 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fef1038ebe9
RSP: 002b:00007fef1114c038 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffec RBX: 00007fef105b6090 RCX: 00007fef1038ebe9
RDX: 00002000000000c0 RSI: 0000200000000080 RDI: 0000000000000000
RBP: 00007fef10411e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000010 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fef105b6128 R14: 00007fef105b6090 R15: 00007fff4cf88218
 </TASK>

Showing all locks held in the system:
1 lock held by ksoftirqd/0/15:
 #0: ffff8880b8639e18 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0xad/0x140 kernel/sched/core.c:614
1 lock held by khungtaskd/31:
 #0: ffffffff8e13f0e0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8e13f0e0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #0: ffffffff8e13f0e0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6770
3 locks held by kworker/u8:8/3020:
2 locks held by getty/5595:
 #0: ffff88814c89c0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc9000333b2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x43e/0x1400 drivers/tty/n_tty.c:2222
1 lock held by syz-executor/15421:
2 locks held by syz.7.2916/15838:
 #0: ffffffff8f5701f0 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1218
 #1: ffffffff8e41a568 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_listener_set_doit+0x12a/0x1650 fs/nfsd/nfsctl.c:1922
2 locks held by syz.6.3032/16286:
 #0: ffff88802cbb40e0 (&type->s_umount_key#91){++++}-{4:4}, at: __super_lock fs/super.c:57 [inline]
 #0: ffff88802cbb40e0 (&type->s_umount_key#91){++++}-{4:4}, at: __super_lock_excl fs/super.c:72 [inline]
 #0: ffff88802cbb40e0 (&type->s_umount_key#91){++++}-{4:4}, at: deactivate_super+0xa9/0xe0 fs/super.c:506
 #1: ffffffff8e41a568 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x4e/0xd0 fs/nfsd/nfssvc.c:596
1 lock held by syz.8.3054/16384:
 #0: ffff88802cbb40e0 (&type->s_umount_key#91){++++}-{4:4}, at: __super_lock fs/super.c:59 [inline]
 #0: ffff88802cbb40e0 (&type->s_umount_key#91){++++}-{4:4}, at: super_lock+0x2a9/0x3b0 fs/super.c:121
1 lock held by syz-executor/16422:
 #0: ffffffff8e144bf8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock kernel/rcu/tree_exp.h:336 [inline]
 #0: ffffffff8e144bf8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x3b9/0x730 kernel/rcu/tree_exp.h:998
3 locks held by kworker/1:3/17530:
 #0: ffff88801a480d48 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3213 [inline]
 #0: ffff88801a480d48 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0 kernel/workqueue.c:3321
 #1: ffffc9000c417bc0 (free_ipc_work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3214 [inline]
 #1: ffffc9000c417bc0 (free_ipc_work){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0 kernel/workqueue.c:3321
 #2: ffffffff8e144bf8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock kernel/rcu/tree_exp.h:336 [inline]
 #2: ffffffff8e144bf8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x3b9/0x730 kernel/rcu/tree_exp.h:998
1 lock held by syz.1.3352/17551:
 #0: ffffc9000c8810a8 (&kvm->slots_lock){+.+.}-{4:4}, at: kvm_vm_ioctl_clear_dirty_log+0x27/0x8f0 virt/kvm/kvm_main.c:2410
7 locks held by syz.1.3352/17554:

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

NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 31 Comm: khungtaskd Not tainted 6.16.0-syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x39e/0x3d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x17a/0x300 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:158 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:307 [inline]
 watchdog+0xfee/0x1030 kernel/hung_task.c:470
 kthread+0x70e/0x8a0 kernel/kthread.c:464
 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted 6.16.0-syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:pv_native_safe_halt+0x13/0x20 arch/x86/kernel/paravirt.c:82
Code: 53 de 02 00 cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 0f 00 2d d3 ad 21 00 f3 0f 1e fa fb f4 <c3> cc cc cc cc cc cc cc cc cc cc cc cc 90 90 90 90 90 90 90 90 90
RSP: 0018:ffffffff8de07d80 EFLAGS: 000002c2
RAX: 0e7134094a956d00 RBX: ffffffff81976918 RCX: 0e7134094a956d00
RDX: 0000000000000001 RSI: ffffffff8d982fba RDI: ffffffff8be1ba40
RBP: ffffffff8de07ea8 R08: ffff8880b8632f5b R09: 1ffff110170c65eb
R10: dffffc0000000000 R11: ffffed10170c65ec R12: ffffffff8fa0b3f0
R13: 0000000000000000 R14: 0000000000000000 R15: 1ffffffff1bd2a50
FS:  0000000000000000(0000) GS:ffff888125c57000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000404030 CR3: 000000007992e000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 arch_safe_halt arch/x86/include/asm/paravirt.h:107 [inline]
 default_idle+0x13/0x20 arch/x86/kernel/process.c:749
 default_idle_call+0x74/0xb0 kernel/sched/idle.c:117
 cpuidle_idle_call kernel/sched/idle.c:185 [inline]
 do_idle+0x1e8/0x510 kernel/sched/idle.c:325
 cpu_startup_entry+0x44/0x60 kernel/sched/idle.c:423
 rest_init+0x2de/0x300 init/main.c:745
 start_kernel+0x47d/0x500 init/main.c:1102
 x86_64_start_reservations+0x24/0x30 arch/x86/kernel/head64.c:307
 x86_64_start_kernel+0x143/0x1c0 arch/x86/kernel/head64.c:288
 common_startup_64+0x13e/0x147
 </TASK>