INFO: task syz.0.25077:15470 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /pro
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.25077     state:D stack:27328 pid:15470 tgid:15469 ppid:5603   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_listener_set_doit+0x53d/0x1ab0
 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+0x14e/0x190
 ____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: 0033:0x7f602dd9e199
RSP: 002b:00007f602ed20028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f602e025fa0 RCX: 00007f602dd9e199
RDX: 000000000000c000 RSI: 0000200000000100 RDI: 0000000000000004
RBP: 00007f602de350b8 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f602e026038 R14: 00007f602e025fa0 R15: 00007ffc9db10108
 </TASK>

Showing all locks held in the system:
locks held by rcu_exp_gp_kthr/19: 1, last CPU#0:
 #0: ffffffff8ed62cf0 (rcu_state.exp_wake_mutex){+.+.}-{4:4}, at: rcu_exp_sel_wait_wake+0xb74/0x1170
locks held by ksoftirqd/1/24: 1, last CPU#1:
 #0: ffff88823c628298 (hrtimer_bases.lock){-.-.}-{2:2}, at: __hrtimer_run_queues+0x466/0xa10
locks held by khungtaskd/35: 1, last CPU#0:
 #0: ffffffff8ed5c8a0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
locks held by getty/5421: 2, on CPU#1:
 #0: ffff88816d85a0a0 (&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/u8:5/27271: 3, on CPU#1:
 #0: ffff888115081940 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #1: ffffc90009057c40 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #2: ffffffff90254da0 (rtnl_mutex){+.+.}-{4:4}, at: addrconf_dad_work+0x116/0x15c0
locks held by kworker/u8:6/6670: 4, on CPU#1:
 #0: ffff8881012d5940 ((wq_completion)netns){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #1: ffffc900088b7c40 (net_cleanup_work){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #2: ffffffff90246488 (pernet_ops_rwsem){++++}-{4:4}, at: cleanup_net+0xf5/0x810
 #3: ffffffff8ed62c68 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x38d/0x770
locks held by syz.3.24812/14401: 2, on CPU#0:
 #0: ffffffff902b91e8 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff8f09f7c0 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_listener_set_doit+0x53d/0x1ab0
locks held by syz.0.25077/15470: 2, on CPU#0:
 #0: ffffffff902b91e8 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff8f09f7c0 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_listener_set_doit+0x53d/0x1ab0
locks held by syz-executor/19104: 7, on CPU#0:
 #0: ffff88816d432460 (sb_writers#7){.+.+}-{0:0}, at: vfs_write+0x22b/0xba0
 #1: ffff88816d4ba080 (&of->mutex){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x1d8/0x540
 #2: ffff88810c3db968 (kn->active#48){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x22b/0x540
 #3: ffffffff8facc080 (nsim_bus_dev_list_lock){+.+.}-{4:4}, at: del_device_store+0xd6/0x370
 #4: ffff8881ba487128 (&dev->mutex){....}-{4:4}, at: device_release_driver_internal+0xb9/0x880
 #5: ffff8881ba486258 (&devlink->lock_key#6){+.+.}-{4:4}, at: nsim_drv_remove+0x50/0x170
 #6: ffffffff90254da0 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_dev_lock+0x257/0x2f0
locks held by syz.5.26005/19213: 5, last CPU#0:
 #0: ffffffff90254da0 (rtnl_mutex){+.+.}-{4:4}, at: tun_chr_close+0x3e/0x1c0
 #1: ffff8881012d42a0 (&root->kernfs_supers_rwsem){++++}-{4:4}, at: kernfs_remove_by_name_ns+0x3f/0x140
 #2: ffff8881012d4180 (&root->kernfs_rwsem){++++}-{4:4}, at: kernfs_remove_by_name_ns+0x4e/0x140
 #3: ffffffff8ed5c8a0 (rcu_read_lock){....}-{1:3}, at: kernfs_root+0x1c/0x230
 #4: ffff88812103bb20 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2d/0x160
locks held by syz.4.26007/19219: 1, on CPU#0:
 #0: ffffffff90254da0 (rtnl_mutex){+.+.}-{4:4}, at: tun_chr_close+0x3e/0x1c0

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

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 35 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: 82 54 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 8c 85 c4 fc 41 03 2e 89 d8 89 ea ee <5b> 41 5c 41 5e 41 5f 5d e9 47 ae 75 06 cc 44 89 f9 80 e1 07 38 c1
RSP: 0018:ffffc90000157900 EFLAGS: 00000002
RAX: 000000000000005b RBX: 000000000000005b RCX: 0000000000000000
RDX: 00000000000003f8 RSI: 0000000000000000 RDI: 0000000000000020
RBP: 00000000000003f8 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: ffffffff85737b50 R12: dffffc0000000000
R13: 000000000000005b R14: ffffffff9ad31300 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8882a8cda000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000563eac4b1950 CR3: 000000019bc7e000 CR4: 00000000000006f0
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>
