INFO: task syz.5.4120:18104 blocked for more than 143 seconds.
      Tainted: G             L      syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.5.4120      state:D stack:28368 pid:18104 tgid:18103 ppid:6529   task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5510 [inline]
 __schedule+0x125c/0x6730 kernel/sched/core.c:7234
 __schedule_loop kernel/sched/core.c:7311 [inline]
 schedule+0xdd/0x2c0 kernel/sched/core.c:7326
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7383
 __mutex_lock_common kernel/locking/mutex.c:726 [inline]
 __mutex_lock+0xccc/0x1bd0 kernel/locking/mutex.c:821
 write_versions+0x9d/0xba0 fs/nfsd/nfsctl.c:701
 nfsctl_transaction_write+0x106/0x1a0 fs/nfsd/nfsctl.c:112
 vfs_write+0x2aa/0x1050 fs/read_write.c:685
 ksys_write+0x12a/0x250 fs/read_write.c:739
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f8a5bb9de99
RSP: 002b:00007f8a5cad9028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f8a5be25fa0 RCX: 00007f8a5bb9de99
RDX: 0000000000000006 RSI: 00002000000001c0 RDI: 0000000000000004
RBP: 00007f8a5bc33eaf R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f8a5be26038 R14: 00007f8a5be25fa0 R15: 00007ffe87386028
 </TASK>
INFO: task syz.5.4120:18113 blocked for more than 144 seconds.
      Tainted: G             L      syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.5.4120      state:D stack:28776 pid:18113 tgid:18103 ppid:6529   task_flags:0x400040 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5510 [inline]
 __schedule+0x125c/0x6730 kernel/sched/core.c:7234
 __schedule_loop kernel/sched/core.c:7311 [inline]
 schedule+0xdd/0x2c0 kernel/sched/core.c:7326
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7383
 __mutex_lock_common kernel/locking/mutex.c:726 [inline]
 __mutex_lock+0xccc/0x1bd0 kernel/locking/mutex.c:821
 write_ports+0xa5/0xcc0 fs/nfsd/nfsctl.c:860
 nfsctl_transaction_write+0x106/0x1a0 fs/nfsd/nfsctl.c:112
 vfs_write+0x2aa/0x1050 fs/read_write.c:685
 ksys_write+0x12a/0x250 fs/read_write.c:739
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f8a5bb9de99
RSP: 002b:00007f8a5cab8028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f8a5be26090 RCX: 00007f8a5bb9de99
RDX: 0000000000000002 RSI: 0000200000000240 RDI: 0000000000000005
RBP: 00007f8a5bc33eaf R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f8a5be26128 R14: 00007f8a5be26090 R15: 00007ffe87386028
 </TASK>
INFO: task syz.5.4120:18117 blocked for more than 144 seconds.
      Tainted: G             L      syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.5.4120      state:D stack:28776 pid:18117 tgid:18103 ppid:6529   task_flags:0x400040 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5510 [inline]
 __schedule+0x125c/0x6730 kernel/sched/core.c:7234
 __schedule_loop kernel/sched/core.c:7311 [inline]
 schedule+0xdd/0x2c0 kernel/sched/core.c:7326
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7383
 __mutex_lock_common kernel/locking/mutex.c:726 [inline]
 __mutex_lock+0xccc/0x1bd0 kernel/locking/mutex.c:821
 write_threads+0x278/0x570 fs/nfsd/nfsctl.c:432
 nfsctl_transaction_write+0x106/0x1a0 fs/nfsd/nfsctl.c:112
 vfs_write+0x2aa/0x1050 fs/read_write.c:685
 ksys_write+0x12a/0x250 fs/read_write.c:739
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f8a5bb9de99
RSP: 002b:00007f8a5ca97028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f8a5be26180 RCX: 00007f8a5bb9de99
RDX: 0000000000000002 RSI: 00002000000002c0 RDI: 0000000000000006
RBP: 00007f8a5bc33eaf R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f8a5be26218 R14: 00007f8a5be26180 R15: 00007ffe87386028
 </TASK>
INFO: task syz.8.4134:18167 blocked for more than 145 seconds.
      Tainted: G             L      syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.8.4134      state:D stack:28456 pid:18167 tgid:18166 ppid:12990  task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5510 [inline]
 __schedule+0x125c/0x6730 kernel/sched/core.c:7234
 __schedule_loop kernel/sched/core.c:7311 [inline]
 schedule+0xdd/0x2c0 kernel/sched/core.c:7326
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7383
 __mutex_lock_common kernel/locking/mutex.c:726 [inline]
 __mutex_lock+0xccc/0x1bd0 kernel/locking/mutex.c:821
 nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:576
 nfsd_umount+0x3b/0x60 fs/nfsd/nfsctl.c:1365
 deactivate_locked_super+0xc1/0x1b0 fs/super.c:477
 deactivate_super fs/super.c:510 [inline]
 deactivate_super+0xe7/0x110 fs/super.c:506
 cleanup_mnt+0x21f/0x450 fs/namespace.c:1317
 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:70 [inline]
 exit_to_user_mode_loop+0x1d8/0x6f0 kernel/entry/common.c:101
 __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:230 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:318 [inline]
 do_syscall_64+0x666/0x870 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f80bad9de99
RSP: 002b:00007f80bbbb7028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: fffffffffffffffe RBX: 00007f80bb025fa0 RCX: 00007f80bad9de99
RDX: 0000200000000280 RSI: 0000200000000240 RDI: 0000000000000000
RBP: 00007f80bae33eaf R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f80bb026038 R14: 00007f80bb025fa0 R15: 00007ffe1bcc6bc8
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/31:
 #0: ffffffff8ebe8180 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
 #0: ffffffff8ebe8180 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:840 [inline]
 #0: ffffffff8ebe8180 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x3d/0x184 kernel/locking/lockdep.c:6775
2 locks held by getty/5366:
 #0: ffff8880334900a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243
 #1: ffffc900032332e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x419/0x14e0 drivers/tty/n_tty.c:2211
3 locks held by kworker/1:13/9465:
 #0: ffff88801bc0f140 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x12b1/0x1940 kernel/workqueue.c:3297
 #1: ffffc900070bfd08 (free_ipc_work){+.+.}-{0:0}, at: process_one_work+0x988/0x1940 kernel/workqueue.c:3298
 #2: ffffffff8ebf3c28 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock+0x19e/0x3c0 kernel/rcu/tree_exp.h:343
4 locks held by kworker/u9:0/14276:
 #0: ffff888083a44940 ((wq_completion)hci10){+.+.}-{0:0}, at: process_one_work+0x12b1/0x1940 kernel/workqueue.c:3297
 #1: ffffc90005d3fd08 ((work_completion)(&hdev->error_reset)){+.+.}-{0:0}, at: process_one_work+0x988/0x1940 kernel/workqueue.c:3298
 #2: ffff88801fea0ea0 (&hdev->req_lock){+.+.}-{4:4}, at: hci_dev_do_close+0x26/0xb0 net/bluetooth/hci_core.c:497
 #3: ffff88801fea00b8 (&hdev->lock){+.+.}-{4:4}, at: hci_dev_close_sync+0x37e/0x13c0 net/bluetooth/hci_sync.c:5438
3 locks held by syz.0.3134/14921:
 #0: ffff88807a8d95f0 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x2aa/0x380 fs/file.c:1259
 #1: ffff8880345fc450 (sb_writers#28){.+.+}-{0:0}, at: ksys_write+0x12a/0x250 fs/read_write.c:739
 #2: ffffffff8f0723e0 (nfsd_mutex){+.+.}-{4:4}, at: write_threads+0x278/0x570 fs/nfsd/nfsctl.c:432
3 locks held by syz.5.4120/18104:
 #0: ffff88802cf1a7f0 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x2aa/0x380 fs/file.c:1259
 #1: ffff888054228450 (sb_writers#28){.+.+}-{0:0}, at: ksys_write+0x12a/0x250 fs/read_write.c:739
 #2: ffffffff8f0723e0 (nfsd_mutex){+.+.}-{4:4}, at: write_versions+0x9d/0xba0 fs/nfsd/nfsctl.c:701
3 locks held by syz.5.4120/18113:
 #0: ffff88807f13b7b0 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x2aa/0x380 fs/file.c:1259
 #1: ffff888054228450 (sb_writers#28){.+.+}-{0:0}, at: ksys_write+0x12a/0x250 fs/read_write.c:739
 #2: ffffffff8f0723e0 (nfsd_mutex){+.+.}-{4:4}, at: write_ports+0xa5/0xcc0 fs/nfsd/nfsctl.c:860
3 locks held by syz.5.4120/18117:
 #0: ffff88807a355eb0 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x2aa/0x380 fs/file.c:1259
 #1: ffff888054228450 (sb_writers#28){.+.+}-{0:0}, at: ksys_write+0x12a/0x250 fs/read_write.c:739
 #2: ffffffff8f0723e0 (nfsd_mutex){+.+.}-{4:4}, at: write_threads+0x278/0x570 fs/nfsd/nfsctl.c:432
2 locks held by syz.8.4134/18167:
 #0: ffff88802ceac0d8 (&type->s_umount_key#86){++++}-{4:4}, at: __super_lock fs/super.c:58 [inline]
 #0: ffff88802ceac0d8 (&type->s_umount_key#86){++++}-{4:4}, at: __super_lock_excl fs/super.c:73 [inline]
 #0: ffff88802ceac0d8 (&type->s_umount_key#86){++++}-{4:4}, at: deactivate_super fs/super.c:509 [inline]
 #0: ffff88802ceac0d8 (&type->s_umount_key#86){++++}-{4:4}, at: deactivate_super+0xdf/0x110 fs/super.c:506
 #1: ffffffff8f0723e0 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:576
1 lock held by syz.3.4404/19353:
 #0: ffff88802ceac0d8 (&type->s_umount_key#86){++++}-{4:4}, at: __super_lock fs/super.c:60 [inline]
 #0: ffff88802ceac0d8 (&type->s_umount_key#86){++++}-{4:4}, at: super_lock+0x320/0x3f0 fs/super.c:122
1 lock held by syz.1.4453/19506:
 #0: ffff88802ceac0d8 (&type->s_umount_key#86){++++}-{4:4}, at: __super_lock fs/super.c:60 [inline]
 #0: ffff88802ceac0d8 (&type->s_umount_key#86){++++}-{4:4}, at: super_lock+0x320/0x3f0 fs/super.c:122
1 lock held by syz.1.4453/19510:
 #0: ffff88802ceac0d8 (&type->s_umount_key#86){++++}-{4:4}, at: __super_lock fs/super.c:60 [inline]
 #0: ffff88802ceac0d8 (&type->s_umount_key#86){++++}-{4:4}, at: super_lock+0x320/0x3f0 fs/super.c:122
1 lock held by syz.1.4453/19511:
 #0: ffff88802ceac0d8 (&type->s_umount_key#86){++++}-{4:4}, at: __super_lock fs/super.c:60 [inline]
 #0: ffff88802ceac0d8 (&type->s_umount_key#86){++++}-{4:4}, at: super_lock+0x320/0x3f0 fs/super.c:122
3 locks held by syz-executor/19527:
 #0: ffff888051a54ea0 (&hdev->req_lock){+.+.}-{4:4}, at: hci_dev_do_close+0x26/0xb0 net/bluetooth/hci_core.c:497
 #1: ffff888051a540b8 (&hdev->lock){+.+.}-{4:4}, at: hci_dev_close_sync+0x37e/0x13c0 net/bluetooth/hci_sync.c:5438
 #2: ffffffff90d2ae00 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_disconn_cfm include/net/bluetooth/hci_core.h:2149 [inline]
 #2: ffffffff90d2ae00 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_conn_hash_flush+0xbb/0x280 net/bluetooth/hci_conn.c:2733
4 locks held by syz-executor/19760:
 #0: ffff8880828a8ea0 (&hdev->req_lock){+.+.}-{4:4}, at: hci_dev_do_close+0x26/0xb0 net/bluetooth/hci_core.c:497
 #1: ffff8880828a80b8 (&hdev->lock){+.+.}-{4:4}, at: hci_dev_close_sync+0x37e/0x13c0 net/bluetooth/hci_sync.c:5438
 #2: ffffffff90d2ae00 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_disconn_cfm include/net/bluetooth/hci_core.h:2149 [inline]
 #2: ffffffff90d2ae00 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_conn_hash_flush+0xbb/0x280 net/bluetooth/hci_conn.c:2733
 #3: ffff88807c672af8 (&conn->lock#2){+.+.}-{4:4}, at: l2cap_conn_del+0xa1/0x6b0 net/bluetooth/l2cap_core.c:1808
1 lock held by syz.4.4502/19765:
 #0: ffff88802ceac0d8 (&type->s_umount_key#86){++++}-{4:4}, at: __super_lock fs/super.c:60 [inline]
 #0: ffff88802ceac0d8 (&type->s_umount_key#86){++++}-{4:4}, at: super_lock+0x320/0x3f0 fs/super.c:122
2 locks held by syz.9.4505/19807:
 #0: ffff8880324c8ea0 (&hdev->req_lock){+.+.}-{4:4}, at: hci_dev_do_close+0x26/0xb0 net/bluetooth/hci_core.c:497
 #1: ffffffff8ebf3c28 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock+0x19e/0x3c0 kernel/rcu/tree_exp.h:343
1 lock held by syz.7.4561/20202:
 #0: ffff88802ceac0d8 (&type->s_umount_key#86){++++}-{4:4}, at: __super_lock fs/super.c:60 [inline]
 #0: ffff88802ceac0d8 (&type->s_umount_key#86){++++}-{4:4}, at: super_lock+0x320/0x3f0 fs/super.c:122
2 locks held by syz-executor/20379:
 #0: ffff8880354bcea0 (&hdev->req_lock){+.+.}-{4:4}, at: hci_dev_do_close+0x26/0xb0 net/bluetooth/hci_core.c:497
 #1: ffff8880354bc0b8 (&hdev->lock){+.+.}-{4:4}, at: hci_dev_close_sync+0x37e/0x13c0 net/bluetooth/hci_sync.c:5438

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

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 31 Comm: khungtaskd Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
Call Trace:
 <TASK>
 __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:122
 nmi_trigger_cpumask_backtrace+0x21c/0x2a0 lib/nmi_backtrace.c:65
 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
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
RIP: 0010:pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:64
Code: d6 8b 02 c3 cc cc cc cc 0f 1f 00 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 c3 7e 10 00 fb f4 <e9> bc 48 03 00 66 2e 0f 1f 84 00 00 00 00 00 66 90 90 90 90 90 90
RSP: 0018:ffffc90000197e00 EFLAGS: 00000242
RAX: 0000000000b9a2a7 RBX: ffff88801eac2540 RCX: ffffffff8bbb22d5
RDX: 0000000000000000 RSI: ffffffff8e1a5b18 RDI: ffffffff8c401580
RBP: ffffed1003d584a8 R08: 0000000000000001 R09: ffffed10170a678d
R10: ffff8880b8533c6b R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 1ffff92000032fc4 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff888123edc000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000032000 CR3: 000000000e994000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 arch_safe_halt arch/x86/include/asm/paravirt.h:62 [inline]
 default_idle+0x9/0x10 arch/x86/kernel/process.c:768
 default_idle_call+0x6c/0xb0 kernel/sched/idle.c:122
 cpuidle_idle_call kernel/sched/idle.c:199 [inline]
 do_idle+0x3a7/0x5b0 kernel/sched/idle.c:355
 cpu_startup_entry+0x4f/0x60 kernel/sched/idle.c:454
 start_secondary+0x21d/0x2d0 arch/x86/kernel/smpboot.c:312
 common_startup_64+0x13e/0x158
 </TASK>