INFO: task syz.0.1914:13179 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.1914      state:D stack:25176 pid:13179 tgid:13178 ppid:5601   task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 __schedule+0x17db/0x58f0
 schedule+0x164/0x2b0
 schedule_preempt_disabled+0x13/0x30
 __mutex_lock+0x7c1/0x1550
 nfsd_nl_threads_get_doit+0x1c0/0x790
 genl_family_rcv_msg_doit+0x233/0x340
 genl_rcv_msg+0x614/0x7a0
 netlink_rcv_skb+0x226/0x4a0
 genl_rcv+0x28/0x40
 netlink_unicast+0x7bd/0x940
 netlink_sendmsg+0x813/0xb40
 sock_sendmsg_nosec+0x13a/0x180
 ____sys_sendmsg+0x54e/0x850
 ___sys_sendmsg+0x2a5/0x360
 __x64_sys_sendmsg+0x1b1/0x290
 do_syscall_64+0x166/0x520
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fc90179e159
RSP: 002b:00007fc9025eb028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fc901a25fa0 RCX: 00007fc90179e159
RDX: 0000000004004990 RSI: 0000200000000040 RDI: 0000000000000009
RBP: 00007fc901835024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fc901a26038 R14: 00007fc901a25fa0 R15: 00007ffddc005ee8
 </TASK>

Showing all locks held in the system:
locks held by kworker/0:1/10: 3, on CPU#0:
 #0: ffff88810006b140 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #1: ffffc900000f7c40 ((work_completion)(&data->fib_event_work)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #2: ffff8881a3bb5250 (&data->fib_lock){+.+.}-{4:4}, at: nsim_fib_event_work+0x1fd/0x3b0
locks held by pr/ttyS0/16: 2, last CPU#1:
 #0: ffffffff8ec363b8 (console_srcu){....}-{0:0}, at: console_srcu_read_lock+0x30/0x60
 #1: ffffffff9ad360d8 (&port_lock_key){-...}-{3:3}, at: univ8250_console_device_lock+0x67/0xc0
locks held by kworker/1:0/25: 4, last CPU#1:
 #0: ffff88810006b140 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #1: ffffc900001f7c40 ((work_completion)(&helper->damage_work)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #2: ffffc900001f7770 (crtc_ww_class_acquire){+.+.}-{0:0}, at: drm_atomic_helper_dirtyfb+0x106/0xfd0
 #3: ffffc900001f7798 (crtc_ww_class_mutex){+.+.}-{4:4}, at: drm_atomic_helper_dirtyfb+0x106/0xfd0
locks held by khungtaskd/34: 1, last CPU#0:
 #0: ffffffff8ed5c7e0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
locks held by kworker/1:1/47: 4, on CPU#1:
 #0: ffff888100692d40 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #1: ffffc90000b77c40 ((work_completion)(&(&ssp->srcu_sup->work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #2: ffffffff8ed5d6a8 (&ssp->srcu_sup->srcu_gp_mutex){+.+.}-{4:4}, at: process_srcu+0x6c/0x16f0
 #3: ffffffff8ed62ba8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x2d0/0x770
locks held by getty/5424: 2, on CPU#1:
 #0: ffff888176cb50a0 (&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
locks held by kworker/1:5/5668: 4, on CPU#1:
 #0: ffff888100692d40 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #1: ffffc90004c6fc40 ((work_completion)(&(&ssp->srcu_sup->work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #2: ffffffff8edbdb68 (&ssp->srcu_sup->srcu_gp_mutex){+.+.}-{4:4}, at: process_srcu+0x6c/0x16f0
 #3: ffffffff8ed62ba8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x38d/0x770
locks held by kworker/0:6/9588: 2, on CPU#0:
 #0: ffff88810006b140 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #1: ffffc90004a6fc40 (free_ipc_work){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
locks held by syz.3.1912/13176: 2, on CPU#0:
 #0: ffffffff902c2b28 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff8f09f100 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_listener_set_doit+0x53d/0x1ab0
locks held by syz.0.1914/13179: 2, on CPU#0:
 #0: ffffffff902c2b28 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff8f09f100 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_threads_get_doit+0x1c0/0x790
locks held by syz.5.2085/13966: 2, on CPU#0:
 #0: ffffffff902c2b28 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff8f09f100 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_cache_flush_doit+0xb5/0x1b0
locks held by syz.9.2209/14530: 2, on CPU#0:
 #0: ffffffff902c2b28 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff8f09f100 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_version_set_doit+0xcd/0x7a0
locks held by syz.2.2773/17019: 1, on CPU#0:
 #0: ffffffff8edcf460 (event_mutex){+.+.}-{4:4}, at: perf_trace_destroy+0x2e/0x150
locks held by syz.2.2773/17033: 1, last CPU#1:
 #0: ffffffff8ed5c7e0 (rcu_read_lock){....}-{1:3}, at: bpf_test_timer_enter+0xf9/0x260
locks held by syz.1.2774/17028: 1, on CPU#0:
 #0: ffff8881bc6ef440 (&sb->s_type->i_mutex_key#13){+.+.}-{4:4}, at: __sock_release+0x7a/0x1f0
locks held by syz.4.2776/17040: 1, on CPU#1:
 #0: ffffffff8edcf460 (event_mutex){+.+.}-{4:4}, at: perf_trace_destroy+0x2e/0x150

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

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 34 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(full) 
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+0x17d/0x390
 sys_info+0x135/0x170
 watchdog+0xfd7/0x1030
 kthread+0x38b/0x480
 ret_from_fork+0x514/0xb70
 ret_from_fork_asm+0x1a/0x30
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 16 Comm: pr/ttyS0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:io_serial_out+0x7c/0xc0
Code: 31 55 fc 44 89 f9 d3 e5 49 83 c6 40 4c 89 f0 48 c1 e8 03 42 80 3c 20 00 74 08 4c 89 f7 e8 bc 67 c5 fc 41 03 2e 89 d8 89 ea ee <5b> 41 5c 41 5e 41 5f 5d c3 cc cc cc cc cc 44 89 f9 80 e1 07 38 c1
RSP: 0018:ffffc90000157900 EFLAGS: 00000002
RAX: 0000000000000020 RBX: 0000000000000020 RCX: 0000000000000000
RDX: 00000000000003f8 RSI: 0000000000000000 RDI: 0000000000000020
RBP: 00000000000003f8 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: ffffffff8572a420 R12: dffffc0000000000
R13: 0000000000000020 R14: ffffffff9ad36100 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8882a8cd5000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fa3b5feb840 CR3: 00000001a8e10000 CR4: 00000000000006f0
DR0: 0000000000000000 DR1: 0000200000000300 DR2: 0000200000000300
DR3: 0000200000000300 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <TASK>
 __serial8250_console_fifo_write+0x1e6/0x3e0
 serial8250_console_write+0xaa1/0x1200
 nbcon_emit_next_record+0xef5/0x1a90
 nbcon_kthread_func+0x679/0x880
 kthread+0x38b/0x480
 ret_from_fork+0x514/0xb70
 ret_from_fork_asm+0x1a/0x30
 </TASK>
