INFO: task syz.3.3139:16884 blocked for more than 144 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.3.3139      state:D stack:26688 pid:16884 tgid:16883 ppid:5634   task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5510 [inline]
 __schedule+0x17d9/0x56c0 kernel/sched/core.c:7234
 __schedule_loop kernel/sched/core.c:7311 [inline]
 schedule+0x164/0x2b0 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+0x7bf/0x1550 kernel/locking/mutex.c:821
 write_threads+0x39d/0x5a0 fs/nfsd/nfsctl.c:432
 nfsctl_transaction_write+0x10f/0x160 fs/nfsd/nfsctl.c:112
 vfs_write+0x296/0xba0 fs/read_write.c:685
 ksys_write+0x150/0x270 fs/read_write.c:739
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fd0c199e019
RSP: 002b:00007fd0c27f2028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fd0c1c25fa0 RCX: 00007fd0c199e019
RDX: 0000000000000002 RSI: 00002000000002c0 RDI: 0000000000000004
RBP: 00007fd0c1a3500c R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fd0c1c26038 R14: 00007fd0c1c25fa0 R15: 00007ffe13cb9ec8
 </TASK>
INFO: task syz.7.3141:16891 blocked for more than 145 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.7.3141      state:D stack:27704 pid:16891 tgid:16890 ppid:11882  task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5510 [inline]
 __schedule+0x17d9/0x56c0 kernel/sched/core.c:7234
 __schedule_loop kernel/sched/core.c:7311 [inline]
 schedule+0x164/0x2b0 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+0x7bf/0x1550 kernel/locking/mutex.c:821
 write_threads+0x39d/0x5a0 fs/nfsd/nfsctl.c:432
 nfsctl_transaction_write+0x10f/0x160 fs/nfsd/nfsctl.c:112
 vfs_write+0x296/0xba0 fs/read_write.c:685
 ksys_write+0x150/0x270 fs/read_write.c:739
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fa7b9f9e019
RSP: 002b:00007fa7b81f6028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fa7ba225fa0 RCX: 00007fa7b9f9e019
RDX: 0000000000000002 RSI: 00002000000002c0 RDI: 0000000000000004
RBP: 00007fa7ba03500c R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fa7ba226038 R14: 00007fa7ba225fa0 R15: 00007ffd953f9b98
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/32:
 #0: ffffffff8eb59c60 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
 #0: ffffffff8eb59c60 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:840 [inline]
 #0: ffffffff8eb59c60 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775
2 locks held by getty/5376:
 #0: ffff888035ecf0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc900032332e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45a/0x1360 drivers/tty/n_tty.c:2211
2 locks held by syz-executor/16395:
 #0: ffffffff9002dec0 (rtnl_mutex){+.+.}-{4:4}, at: tun_detach drivers/net/tun.c:634 [inline]
 #0: ffffffff9002dec0 (rtnl_mutex){+.+.}-{4:4}, at: tun_chr_close+0x3e/0x1c0 drivers/net/tun.c:3442
 #1: ffffffff8eb5ff68 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock kernel/rcu/tree_exp.h:311 [inline]
 #1: ffffffff8eb5ff68 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x2d0/0x770 kernel/rcu/tree_exp.h:961
1 lock held by syz-executor/16677:
3 locks held by syz.1.3125/16809:
 #0: ffff888021f46b70 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x246/0x320 fs/file.c:1259
 #1: ffff888037556450 (sb_writers#30){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2733 [inline]
 #1: ffff888037556450 (sb_writers#30){.+.+}-{0:0}, at: vfs_write+0x22b/0xba0 fs/read_write.c:683
 #2: ffffffff8ee8e6c0 (nfsd_mutex){+.+.}-{4:4}, at: write_threads+0x39d/0x5a0 fs/nfsd/nfsctl.c:432
3 locks held by syz.3.3139/16884:
 #0: ffff888079cb6470 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x246/0x320 fs/file.c:1259
 #1: ffff888047b04450 (sb_writers#30){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2733 [inline]
 #1: ffff888047b04450 (sb_writers#30){.+.+}-{0:0}, at: vfs_write+0x22b/0xba0 fs/read_write.c:683
 #2: ffffffff8ee8e6c0 (nfsd_mutex){+.+.}-{4:4}, at: write_threads+0x39d/0x5a0 fs/nfsd/nfsctl.c:432
3 locks held by syz.7.3141/16891:
 #0: ffff88802b6520f0 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x246/0x320 fs/file.c:1259
 #1: ffff88807cd0c450 (sb_writers#30){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2733 [inline]
 #1: ffff88807cd0c450 (sb_writers#30){.+.+}-{0:0}, at: vfs_write+0x22b/0xba0 fs/read_write.c:683
 #2: ffffffff8ee8e6c0 (nfsd_mutex){+.+.}-{4:4}, at: write_threads+0x39d/0x5a0 fs/nfsd/nfsctl.c:432
1 lock held by syz-executor/16951:
 #0: ffff888037a88ea0 (&hdev->req_lock){+.+.}-{4:4}, at: hci_dev_do_close net/bluetooth/hci_core.c:497 [inline]
 #0: ffff888037a88ea0 (&hdev->req_lock){+.+.}-{4:4}, at: hci_unregister_dev+0x22a/0x5b0 net/bluetooth/hci_core.c:2678
1 lock held by syz.9.3448/18400:
 #0: ffff88804490cea0 (&hdev->req_lock){+.+.}-{4:4}, at: hci_dev_do_close net/bluetooth/hci_core.c:497 [inline]
 #0: ffff88804490cea0 (&hdev->req_lock){+.+.}-{4:4}, at: hci_unregister_dev+0x22a/0x5b0 net/bluetooth/hci_core.c:2678
1 lock held by syz.8.3451/18418:
 #0: ffff88809a2f4ea0 (&hdev->req_lock){+.+.}-{4:4}, at: hci_dev_do_close net/bluetooth/hci_core.c:497 [inline]
 #0: ffff88809a2f4ea0 (&hdev->req_lock){+.+.}-{4:4}, at: hci_unregister_dev+0x22a/0x5b0 net/bluetooth/hci_core.c:2678

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

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 32 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x274/0x2d0 lib/nmi_backtrace.c:122
 nmi_trigger_cpumask_backtrace+0x17a/0x380 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+0x135/0x170 lib/sys_info.c:165
 check_hung_uninterruptible_tasks kernel/hung_task.c:353 [inline]
 watchdog+0xfd7/0x1030 kernel/hung_task.c:561
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>