INFO: task syz.2.1188:10470 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.2.1188      state:D stack:24112 pid:10470 tgid:10469 ppid:5852   task_flags:0x400140 flags:0x00004004
Call Trace:
 <TASK>
 __schedule+0x1798/0x4cc0
 schedule+0x165/0x360
 schedule_preempt_disabled+0x13/0x30
 __mutex_lock+0x7e6/0x1350
 nfsd_nl_threads_get_doit+0x1b6/0x6f0
 genl_family_rcv_msg_doit+0x215/0x300
 genl_rcv_msg+0x60e/0x790
 netlink_rcv_skb+0x208/0x470
 genl_rcv+0x28/0x40
 netlink_unicast+0x82f/0x9e0
 netlink_sendmsg+0x805/0xb30
 __sock_sendmsg+0x21c/0x270
 ____sys_sendmsg+0x505/0x830
 ___sys_sendmsg+0x21f/0x2a0
 __x64_sys_sendmsg+0x19b/0x260
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f42dd38ec29
RSP: 002b:00007f42db5f6038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f42dd5d5fa0 RCX: 00007f42dd38ec29
RDX: 0000000000008000 RSI: 0000200000006e40 RDI: 0000000000000009
RBP: 00007f42dd411e41 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f42dd5d6038 R14: 00007f42dd5d5fa0 R15: 00007ffd43e6cbf8
 </TASK>

Showing all locks held in the system:
1 lock held by rcu_tasks_trace/32:
 #0: ffffffff8e13ae50 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{4:4}, at: rcu_tasks_one_gp+0xaf9/0xdf0
1 lock held by khungtaskd/34:
 #0: ffffffff8e13a120 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
2 locks held by getty/5674:
 #0: ffff8880280260a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70
 #1: ffffc900029062f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x43e/0x1400
2 locks held by syz.0.422/7521:
 #0: ffffffff8f5a0270 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff8e419548 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_listener_set_doit+0x137/0x1690
2 locks held by syz.2.1188/10470:
 #0: ffffffff8f5a0270 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff8e419548 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_threads_get_doit+0x1b6/0x6f0
3 locks held by syz.1.1389/11284:
 #0: ffffffff8f5a0270 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffff88812de586d8 (nlk_cb_mutex-GENERIC){+.+.}-{4:4}, at: __netlink_dump_start+0xfe/0x7e0
 #2: ffffffff8e419548 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_rpc_status_get_dumpit+0xdf/0x1290
1 lock held by syz.5.1885/13451:
 #0: ffffffff8e19d6c8 (event_mutex){+.+.}-{4:4}, at: perf_trace_destroy+0x2e/0x150
2 locks held by syz.5.1885/13453:
 #0: ffffffff8f5a0270 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff8e419548 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_threads_get_doit+0x1b6/0x6f0
2 locks held by syz.6.1888/13466:
 #0: ffffffff8f52dc90 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x304/0x4d0
 #1: ffffffff8f53ab48 (rtnl_mutex){+.+.}-{4:4}, at: register_nexthop_notifier+0x80/0x210
2 locks held by syz.3.1890/13472:
 #0: ffffffff8f53ab48 (rtnl_mutex){+.+.}-{4:4}, at: tun_chr_close+0x3e/0x1c0
 #1: ffffffff8e13fbb8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x2f6/0x730

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

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+0x189/0x250
 nmi_cpu_backtrace+0x39e/0x3d0
 nmi_trigger_cpumask_backtrace+0x17a/0x300
 watchdog+0xf93/0xfe0
 kthread+0x711/0x8a0
 ret_from_fork+0x439/0x7d0
 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: 13472 Comm: syz.3.1890 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:strcmp+0x28/0xc0
Code: 90 90 f3 0f 1e fa 55 41 57 41 56 41 54 53 48 bb 00 00 00 00 00 fc ff df 45 31 f6 4a 8d 04 37 48 89 c1 48 c1 e9 03 0f b6 0c 19 <84> c9 75 2c 42 0f b6 2c 37 4a 8d 04 36 48 89 c1 48 c1 e9 03 0f b6
RSP: 0018:ffffc90002a0f5e8 EFLAGS: 00000802
RAX: ffffffff8c75ba00 RBX: dffffc0000000000 RCX: 0000000000000000
RDX: 000000008c973a03 RSI: ffffffff8c973a40 RDI: ffffffff8c75ba00
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: fffff52000541eec R12: ffff888045c91298
R13: ffffffff962a15a8 R14: 0000000000000000 R15: ffffffff9353b6d0
FS:  00007f6ae2df66c0(0000) GS:ffff8881a3c12000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c36ad1e CR3: 000000003bdb8000 CR4: 00000000000006f0
DR0: 0000000000000000 DR1: 0000200000000300 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <TASK>
 count_matching_names+0x57/0x90
 register_lock_class+0x23f/0x320
 __lock_acquire+0x99/0xd20
 lock_acquire+0x120/0x360
 _raw_spin_lock_bh+0x36/0x50
 dev_reset_queue+0x138/0x1b0
 dev_deactivate_many+0x720/0xd40
 __dev_close_many+0x162/0x6f0
 netif_close_many+0x225/0x410
 unregister_netdevice_many_notify+0x7b9/0x1ff0
 unregister_netdevice_queue+0x33c/0x380
 __tun_detach+0xda4/0x1560
 tun_chr_close+0x10a/0x1c0
 __fput+0x44c/0xa70
 fput_close_sync+0x119/0x200
 __x64_sys_close+0x7f/0x110
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f6ae4b8ec29
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f6ae2df6038 EFLAGS: 00000246 ORIG_RAX: 0000000000000003
RAX: ffffffffffffffda RBX: 00007f6ae4dd6090 RCX: 00007f6ae4b8ec29
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 00007f6ae4c11e41 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f6ae4dd6128 R14: 00007f6ae4dd6090 R15: 00007ffd1c280848
 </TASK>
