INFO: task syz.1.4255:20477 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.1.4255      state:D stack:24776 pid:20477 tgid:20476 ppid:5610   task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 __schedule+0x17d9/0x56c0
 schedule+0x164/0x2b0
 schedule_preempt_disabled+0x13/0x30
 __mutex_lock+0x7bf/0x1550
 nfsd_nl_cache_flush_doit+0xb5/0x1b0
 genl_family_rcv_msg_doit+0x233/0x340
 genl_rcv_msg+0x614/0x7a0
 netlink_rcv_skb+0x226/0x4a0
 genl_rcv+0x28/0x40
 netlink_unicast+0x7bb/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+0x174/0x580
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb4e439de99
RSP: 002b:00007fb4e51be028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fb4e4625fa0 RCX: 00007fb4e439de99
RDX: 0000000004000080 RSI: 0000200000000100 RDI: 0000000000000007
RBP: 00007fb4e4433eaf R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fb4e4626038 R14: 00007fb4e4625fa0 R15: 00007fff817f13b8
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/34:
 #0: ffffffff8eb59c60 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
2 locks held by getty/5437:
 #0: ffff8881709610a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70
 #1: ffffc900034732e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45a/0x1360
2 locks held by syz.0.3811/18904:
 #0: ffffffff9009daa8 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff8ee8e5a0 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_listener_set_doit+0x135/0x1750
2 locks held by syz.1.4255/20477:
 #0: ffffffff9009daa8 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff8ee8e5a0 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_cache_flush_doit+0xb5/0x1b0
2 locks held by syz.2.5641/25568:
 #0: ffffffff9002d140 (rtnl_mutex){+.+.}-{4:4}, at: tun_chr_close+0x3e/0x1c0
 #1: ffffffff8eb5ff68 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x2d0/0x770

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

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+0xe8/0x150
 nmi_cpu_backtrace+0x274/0x2d0
 nmi_trigger_cpumask_backtrace+0x17a/0x380
 sys_info+0x135/0x170
 watchdog+0xfd7/0x1030
 kthread+0x388/0x470
 ret_from_fork+0x514/0xb70
 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: 1112 Comm: kworker/u10:7 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
Workqueue: events_unbound toggle_allocation_gate
RIP: 0010:debug_object_assert_init+0xf4/0x380
Code: fd 4c 89 34 24 4c 8b 6d 00 45 31 f6 eb 07 4d 8b 6d 00 41 ff c6 4d 85 ed 74 3c 4d 8d 65 18 4c 89 e0 48 c1 e8 03 42 80 3c 38 00 <74> 08 4c 89 e7 e8 22 a2 55 fd 49 39 1c 24 0f 84 f2 00 00 00 4c 89
RSP: 0018:ffffc90006f678a0 EFLAGS: 00000046
RAX: 1ffff1102d4af7c3 RBX: ffffffff9a7f4188 RCX: 0000000000000001
RDX: 0000000000000001 RSI: 0000000000000004 RDI: ffffc90006f67800
RBP: ffffffff9aa14d30 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff52000decf00 R12: ffff88816a57be18
R13: ffff88816a57be00 R14: 000000000000000b R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff88818d950000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007efcdfdeb580 CR3: 000000000e946000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 __mod_timer+0x4b/0xed0
 queue_delayed_work_on+0x11a/0x1e0
 toggle_allocation_gate+0x245/0x290
 process_scheduled_works+0xa8e/0x14e0
 worker_thread+0xa47/0xfb0
 kthread+0x388/0x470
 ret_from_fork+0x514/0xb70
 ret_from_fork_asm+0x1a/0x30
 </TASK>
