INFO: task syz.5.1334:10986 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.5.1334      state:D stack:23024 pid:10986 tgid:10985 ppid:6021   task_flags:0x400140 flags:0x00004004
Call Trace:
 <TASK>
 __schedule+0x1798/0x4cc0
 schedule+0x165/0x360
 schedule_preempt_disabled+0x13/0x30
 __mutex_lock+0x7e6/0x1360
 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: 0033:0x7fbb3398eba9
RSP: 002b:00007fbb34850038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fbb33bd5fa0 RCX: 00007fbb3398eba9
RDX: 0000000000008000 RSI: 0000200000006e40 RDI: 0000000000000008
RBP: 00007fbb33a11e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fbb33bd6038 R14: 00007fbb33bd5fa0 R15: 00007ffc595ce648
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/34:
 #0: ffffffff8e139ea0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
3 locks held by kworker/1:2/974:
 #0: ffff88801a480d48 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0
 #1: ffffc900068a7bc0 ((work_completion)(&data->fib_event_work)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0
 #2: ffff888124688240 (&data->fib_lock){+.+.}-{4:4}, at: nsim_fib_event_work+0x26b/0x3180
2 locks held by getty/5672:
 #0: ffff8880208f70a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70
 #1: ffffc900026682f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x43e/0x1400
2 locks held by syz-executor/5819:
3 locks held by kworker/u8:3/5878:
 #0: ffff8880262c8948 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0
 #1: ffffc90003b6fbc0 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0
 #2: ffffffff8f537dc8 (rtnl_mutex){+.+.}-{4:4}, at: addrconf_dad_work+0x112/0x14b0
3 locks held by kworker/0:4/5886:
 #0: ffff88801a480d48 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0
 #1: ffffc90003c6fbc0 ((work_completion)(&data->fib_event_work)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0
 #2: ffff88812468e240 (&data->fib_lock){+.+.}-{4:4}, at: nsim_fib_event_work+0x26b/0x3180
2 locks held by syz.6.875/9510:
 #0: ffffffff8f59d470 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff8e418588 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_threads_set_doit+0x2cb/0x960
2 locks held by syz-executor/9839:
2 locks held by syz.5.1334/10986:
 #0: ffffffff8f59d470 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff8e418588 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_threads_get_doit+0x1b6/0x6f0
1 lock held by syz-executor/14506:
 #0: ffffffff8f537dc8 (rtnl_mutex){+.+.}-{4:4}, at: devinet_ioctl+0x323/0x1b50
3 locks held by syz-executor/14508:
 #0: ffffffff8f537dc8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_newlink+0x8db/0x1c70
 #1: ffff8880395ed4e8 (&wg->device_update_lock){+.+.}-{4:4}, at: wg_open+0x227/0x420
 #2: ffffffff8e13f938 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x2f6/0x730

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

NMI backtrace for cpu 1
CPU: 1 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+0x3fc/0x770
 ret_from_fork_asm+0x1a/0x30
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 15 Comm: ksoftirqd/0 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:kmem_cache_free+0x8b/0x400
Code: 0d f6 05 05 07 75 0d 01 0f 84 5e 02 00 00 4c 8b 2d 92 03 a5 0b 48 89 df e8 92 24 5c ff 48 c1 e8 06 48 83 e0 c0 49 8b 4c 05 08 <f6> c1 01 0f 85 6f 01 00 00 49 01 c5 0f 1f 44 00 00 41 0f b6 45 33
RSP: 0018:ffffc900001277b0 EFLAGS: 00000206
RAX: 00000000009ad3c0 RBX: ffff888026b4f240 RCX: ffff88801a44b780
RDX: 0000000000000100 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc900001278b0 R08: ffff88804b03fd03 R09: 1ffff11009607fa0
R10: dffffc0000000000 R11: ffffed1009607fa1 R12: dffffc0000000000
R13: ffffea0000000000 R14: ffff88801a44b780 R15: ffffffff820e5eb1
FS:  0000000000000000(0000) GS:ffff8880b861c000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f4674107d60 CR3: 0000000105c5a000 CR4: 00000000000006f0
DR0: 0000000000000000 DR1: 0000000000000082 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <TASK>
 __tlb_remove_table+0x81/0x3b0
 tlb_remove_table_rcu+0x85/0x100
 rcu_core+0xcab/0x1770
 handle_softirqs+0x286/0x870
 run_ksoftirqd+0x9b/0x100
 smpboot_thread_fn+0x542/0xa60
 kthread+0x711/0x8a0
 ret_from_fork+0x3fc/0x770
 ret_from_fork_asm+0x1a/0x30
 </TASK>
