INFO: task syz.0.10647:18035 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.10647     state:D stack:23416 pid:18035 tgid:18028 ppid:5617   task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 __schedule+0x1821/0x5740
 schedule+0x164/0x360
 schedule_preempt_disabled+0x13/0x30
 __mutex_lock+0x7f7/0x1550
 nfsd_nl_listener_set_doit+0x141/0x1670
 genl_family_rcv_msg_doit+0x22a/0x330
 genl_rcv_msg+0x61c/0x7a0
 netlink_rcv_skb+0x232/0x4b0
 genl_rcv+0x28/0x40
 netlink_unicast+0x75c/0x8e0
 netlink_sendmsg+0x813/0xb40
 ____sys_sendmsg+0x972/0x9f0
 ___sys_sendmsg+0x2a5/0x360
 __x64_sys_sendmsg+0x1bd/0x2a0
 do_syscall_64+0x15f/0x560
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f94faf9ce59
RSP: 002b:00007f94f91d5028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f94fb216090 RCX: 00007f94faf9ce59
RDX: 0000000000000000 RSI: 00002000000001c0 RDI: 000000000000000d
RBP: 00007f94fb032d6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f94fb216128 R14: 00007f94fb216090 R15: 00007ffda18cc268
 </TASK>

Showing all locks held in the system:
4 locks held by kworker/u8:1/13:
 #0: ffff8881012b5940 ((wq_completion)netns){+.+.}-{0:0}, at: process_scheduled_works+0xa35/0x1860
 #1: ffffc90000127c40 (net_cleanup_work){+.+.}-{0:0}, at: process_scheduled_works+0xa70/0x1860
 #2: ffffffff8fdc2d68 (pernet_ops_rwsem){++++}-{4:4}, at: cleanup_net+0xf4/0x800
 #3: ffffffff8e962fe8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x2d0/0x770
1 lock held by khungtaskd/34:
 #0: ffffffff8e95cce0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
2 locks held by getty/5437:
 #0: ffff88810d5780a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70
 #1: ffffc900034732e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45c/0x13a0
2 locks held by syz.1.10029/15392:
 #0: ffffffff8fe413a8 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff8ec8b2e0 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_listener_set_doit+0x141/0x1670
2 locks held by syz.0.10647/18035:
 #0: ffffffff8fe413a8 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff8ec8b2e0 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_listener_set_doit+0x141/0x1670
1 lock held by syz.2.11524/21697:
2 locks held by syz.2.11524/21714:
2 locks held by syz.3.11532/21737:

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

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+0x17a/0x300
 sys_info+0x135/0x170
 watchdog+0xfd3/0x1030
 kthread+0x389/0x470
 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: 15795 Comm: syz-executor 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:entry_SYSCALL_64+0x23/0x2b
Code: cc cc cc cc cc cc cc f3 0f 1e fa 0f 01 f8 65 48 89 25 85 1f 38 12 66 90 0f 20 dc 0f 1f 44 00 00 48 81 e4 ff e7 ff ff 0f 22 dc <65> 48 8b 25 65 8f 39 12 6a 2b 65 ff 35 60 1f 38 12 41 53 6a 33 51
RSP: 0018:000000018bb9e000 EFLAGS: 00000006
RAX: 000000000000003d RBX: 000055556af37500 RCX: 00007ffa75b5d68e
RDX: 0000000040000001 RSI: 00007ffc34e6d35c RDI: ffffffffffffffff
RBP: 00007ffc34e6d35c R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000001388
R13: 00000000000927c0 R14: 00000000001c5bbb R15: 00007ffc34e6d3b0
FS:  000055556af37500(0000) GS:ffff8882a9287000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055575148e018 CR3: 000000018bb9e000 CR4: 00000000000006f0
Call Trace:
