INFO: task syz.3.2909:18464 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.3.2909      state:D stack:28808 pid:18464 tgid:18460 ppid:13417  task_flags:0x400040 flags:0x00080002
Call Trace:
 <TASK>
 __schedule+0x17d9/0x56c0
 schedule+0x164/0x2b0
 schedule_preempt_disabled+0x13/0x30
 __mutex_lock+0x7bf/0x1550
 write_ports+0xb5/0xd10
 nfsctl_transaction_write+0x10f/0x160
 vfs_write+0x296/0xba0
 ksys_write+0x150/0x270
 do_syscall_64+0x174/0x580
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe20419e0d9
RSP: 002b:00007fe205104028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fe204426090 RCX: 00007fe20419e0d9
RDX: 0000000000000001 RSI: 0000200000000240 RDI: 0000000000000004
RBP: 00007fe204235024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fe204426128 R14: 00007fe204426090 R15: 00007ffe67195ca8
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/35:
 #0: ffffffff8eb59c60 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
2 locks held by getty/5429:
 #0: ffff88810d5760a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70
 #1: ffffc900034762e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45a/0x1360
3 locks held by kworker/u8:4/7139:
 #0: ffff88812103b160 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2d/0x160
 #1: ffff888121024440 (psi_seq){-.-.}-{0:0}, at: psi_task_switch+0x57/0x7d0
 #2: ffffffff90026a40 (rtnl_mutex){+.+.}-{4:4}, at: addrconf_dad_work+0x116/0x15c0
3 locks held by kworker/0:8/8944:
 #0: ffff88810006b140 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0
 #1: ffffc900035cfc40 ((work_completion)(&data->fib_event_work)){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0
 #2: ffff888116423250 (&data->fib_lock){+.+.}-{4:4}, at: nsim_fib_event_work+0x1fd/0x3b0
2 locks held by kworker/u9:9/9140:
 #0: ffff888169887140 ((wq_completion)iou_exit){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0
 #1: ffffc90003c7fc40 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0
3 locks held by kworker/u11:3/16147:
 #0: ffff88810f58f940 ((wq_completion)hci6){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0
 #1: ffffc90004a5fc40 ((work_completion)(&hdev->power_on)){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0
 #2: ffff888115520ea0 (&hdev->req_lock){+.+.}-{4:4}, at: hci_power_on+0x1a2/0x750
3 locks held by syz.4.2867/18113:
 #0: ffff888110331ef0 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x246/0x320
 #1: ffff8881159e4450 (sb_writers#43){.+.+}-{0:0}, at: vfs_write+0x22b/0xba0
 #2: ffffffff8ee8e2c0 (nfsd_mutex){+.+.}-{4:4}, at: write_ports+0xb5/0xd10
3 locks held by syz.3.2909/18464:
 #0: ffff8881023abaf0 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x246/0x320
 #1: ffff888103fa8450 (sb_writers#43){.+.+}-{0:0}, at: vfs_write+0x22b/0xba0
 #2: ffffffff8ee8e2c0 (nfsd_mutex){+.+.}-{4:4}, at: write_ports+0xb5/0xd10
3 locks held by syz.2.3277/20848:
 #0: ffff888110e5f8f0 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x246/0x320
 #1: ffff888026d82450 (sb_writers#43){.+.+}-{0:0}, at: vfs_write+0x22b/0xba0
 #2: ffffffff8ee8e2c0 (nfsd_mutex){+.+.}-{4:4}, at: write_ports+0xb5/0xd10
3 locks held by syz-executor/21080:
 #0: ffffffff90026a40 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_newlink+0x8a3/0x1bd0
 #1: ffff8881132d1610 (&wg->device_update_lock){+.+.}-{4:4}, at: wg_open+0x227/0x420
 #2: ffffffff8eb5ff68 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x2d0/0x770
2 locks held by syz.0.3332/21285:
 #0: ffff888118bf90a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_release+0xb8/0x520
 #1: ffff888118bff0a0 (&tty->ldisc_sem/1){+.+.}-{0:0}, at: tty_ldisc_release+0xdc/0x520
2 locks held by dhcpcd/21302:
 #0: ffff888174270260 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: packet_do_bind+0x33/0xe90
 #1: ffffffff8eb5ff68 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x38d/0x770

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

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 35 Comm: khungtaskd Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150
 nmi_cpu_backtrace+0x274/0x2d0
 nmi_trigger_cpumask_backtrace+0x17a/0x380
 sys_info+0x135/0x170
 watchdog+0xfd7/0x1030
 kthread+0x388/0x470
 ret_from_fork+0x514/0xb70
 ret_from_fork_asm+0x1a/0x30
 </TASK>
