INFO: task syz.3.2970:16560 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.3.2970      state:D stack:25288 pid:16560 tgid:16559 ppid:10678  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: 0033:0x7fab85b8ebe9
RSP: 002b:00007fab86a1a038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fab85db5fa0 RCX: 00007fab85b8ebe9
RDX: 0000000000008000 RSI: 0000200000006e40 RDI: 0000000000000009
RBP: 00007fab85c11e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fab85db6038 R14: 00007fab85db5fa0 R15: 00007ffd568d7bc8
 </TASK>

Showing all locks held in the system:
1 lock held by rcu_tasks_trace/31:
 #0: ffffffff8e13abd0 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{4:4}, at: rcu_tasks_one_gp+0xaf9/0xdf0
1 lock held by khungtaskd/34:
 #0: ffffffff8e139ea0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
2 locks held by getty/5674:
 #0: ffff8881067fa0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70
 #1: ffffc900029032f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x43e/0x1400
3 locks held by kworker/1:4/5894:
 #0: ffff88801a480d48 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0
 #1: ffffc90003dffbc0 (free_ipc_work){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0
 #2: ffffffff8e13f938 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x3b9/0x730
2 locks held by syz.1.2765/15811:
 #0: ffffffff8f59d470 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff8e418588 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_listener_set_doit+0x137/0x1690
2 locks held by syz.3.2970/16560:
 #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.9.3142/17290:
 #0: ffffffff8e19d448 (event_mutex){+.+.}-{4:4}, at: perf_trace_destroy+0x2e/0x150
1 lock held by syz.8.3143/17298:
2 locks held by syz.7.3144/17294:
 #0: ffffffff8e19d448 (event_mutex){+.+.}-{4:4}, at: perf_trace_destroy+0x2e/0x150
 #1: ffffffff8e13f938 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x3b9/0x730

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

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+0x3fc/0x770
 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: 17298 Comm: syz.8.3143 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:rcu_is_watching+0x60/0xb0
Code: 80 3c 38 00 74 08 4c 89 f7 e8 bc c2 7c 00 48 c7 c3 98 6f a1 92 49 03 1e 48 89 d8 48 c1 e8 03 42 0f b6 04 38 84 c0 75 34 8b 03 <65> ff 0d a9 e1 f9 10 74 11 83 e0 04 c1 e8 02 5b 41 5e 41 5f e9 47
RSP: 0018:ffffc90003bbf4b0 EFLAGS: 00000246
RAX: 00000000000fcbac RBX: ffff888136632f98 RCX: 215b69e79cf9b800
RDX: ffffc90003bbf601 RSI: ffffffff8be332e0 RDI: ffffffff8be332a0
RBP: dffffc0000000000 R08: ffffc90003bbfc30 R09: 0000000000000000
R10: ffffc90003bbf658 R11: fffff52000777ecd R12: ffffc90003bbfc40
R13: ffffffff8172c195 R14: ffffffff8dbded18 R15: dffffc0000000000
FS:  00007fdedabb96c0(0000) GS:ffff8881a3c1c000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fdedabb8fc8 CR3: 000000002a0b4000 CR4: 00000000000006f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000200000000300
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <TASK>
 lock_release+0x4b/0x3e0
 unwind_next_frame+0x19a9/0x2390
 arch_stack_walk+0x11c/0x150
 stack_trace_save+0x9c/0xe0
 save_stack+0xf5/0x1f0
 __reset_page_owner+0x71/0x1f0
 __free_frozen_pages+0xbc4/0xd30
 vfree+0x25a/0x400
 kcov_close+0x28/0x50
 __fput+0x44c/0xa70
 task_work_run+0x1d4/0x260
 do_exit+0x6b5/0x2300
 do_group_exit+0x21c/0x2d0
 get_signal+0x1286/0x1340
 arch_do_signal_or_restart+0x9a/0x750
 exit_to_user_mode_loop+0x75/0x110
 do_syscall_64+0x2bd/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fded9d8ebe9
Code: Unable to access opcode bytes at 0x7fded9d8ebbf.
RSP: 002b:00007fdedabb90e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 00007fded9fb6098 RCX: 00007fded9d8ebe9
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007fded9fb6098
RBP: 00007fded9fb6090 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fded9fb6128 R14: 00007ffd81ee3d40 R15: 00007ffd81ee3e28
 </TASK>
