INFO: task syz.5.4218:20578 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.5.4218      state:D stack:24776 pid:20578 tgid:20577 ppid:20189  task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 __schedule+0x15dd/0x52d0
 schedule+0x164/0x360
 schedule_preempt_disabled+0x13/0x30
 __mutex_lock+0x7fe/0x1300
 nfsd_nl_version_get_doit+0x17c/0xc40
 genl_family_rcv_msg_doit+0x22a/0x330
 genl_rcv_msg+0x61c/0x7a0
 netlink_rcv_skb+0x232/0x4b0
 genl_rcv+0x28/0x40
 netlink_unicast+0x80f/0x9b0
 netlink_sendmsg+0x813/0xb40
 ____sys_sendmsg+0x972/0x9f0
 ___sys_sendmsg+0x2a5/0x360
 __x64_sys_sendmsg+0x1bd/0x2a0
 do_syscall_64+0x14d/0xf80
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7ff29a99c799
RSP: 002b:00007ff29b7cc028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007ff29ac15fa0 RCX: 00007ff29a99c799
RDX: 0000000020048000 RSI: 0000200000000140 RDI: 0000000000000008
RBP: 00007ff29aa32c99 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ff29ac16038 R14: 00007ff29ac15fa0 R15: 00007fffd9b21b18
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/35:
 #0: ffffffff8e75e5e0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
2 locks held by getty/5635:
 #0: ffff88811384d0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70
 #1: ffffc9000356b2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45c/0x13c0
3 locks held by kworker/0:7/7064:
 #0: ffff88810006b148 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0xa52/0x18c0
 #1: ffffc90003cb7c40 ((work_completion)(&data->fib_event_work)){+.+.}-{0:0}, at: process_scheduled_works+0xa8d/0x18c0
 #2: ffff88819801b240 (&data->fib_lock){+.+.}-{4:4}, at: nsim_fib_event_work+0x202/0x3d0
3 locks held by kworker/0:9/7535:
 #0: ffff88810006b148 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0xa52/0x18c0
 #1: ffffc900039b7c40 (free_ipc_work){+.+.}-{0:0}, at: process_scheduled_works+0xa8d/0x18c0
 #2: ffffffff8e764878 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x38d/0x770
2 locks held by syz.1.4010/19822:
 #0: ffffffff8fc3c6f0 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff8ea86108 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_listener_set_doit+0x141/0x1670
2 locks held by syz.5.4218/20578:
 #0: ffffffff8fc3c6f0 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff8ea86108 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_version_get_doit+0x17c/0xc40
2 locks held by dhcpcd/22195:
 #0: ffff8881bedd8208 (&sb->s_type->i_mutex_key#14){+.+.}-{4:4}, at: sock_close+0x9b/0x240
 #1: ffffffff8e764878 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x38d/0x770
2 locks held by syz.6.4899/23512:
 #0: ffffffff8fc3c6f0 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff8ea86108 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_listener_set_doit+0x141/0x1670
1 lock held by syz-executor/23928:
2 locks held by dhcpcd-run-hook/23980:

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

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+0x17a/0x300
 sys_info+0x135/0x170
 watchdog+0xfd9/0x1030
 kthread+0x388/0x470
 ret_from_fork+0x51e/0xb90
 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: 23949 Comm: syz.0.5021 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:unwind_next_frame+0x50f/0x23c0
Code: c1 f9 02 48 c1 e8 3f 48 01 c8 48 83 e0 fe 4c 8d 3c 45 00 00 00 00 49 01 ef 4c 89 f8 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <0f> b6 04 08 84 c0 75 27 49 63 07 4c 01 f8 49 8d 4f 04 4c 39 e0 48
RSP: 0018:ffffc90008a5f558 EFLAGS: 00000a06
RAX: 1ffffffff205ca22 RBX: ffffffff902e5134 RCX: dffffc0000000000
RDX: ffffffff902e50f0 RSI: ffffffff90ac93be RDI: ffffffff8c27c7a0
RBP: ffffffff902e50f0 R08: 0000000000000012 R09: ffffffff8e75e5e0
R10: ffffc90008a5f678 R11: ffffffff81b0c390 R12: ffffffff81c5c477
R13: ffffffff902e50f0 R14: ffffc90008a5f628 R15: ffffffff902e5110
FS:  00007f24cb5956c0(0000) GS:ffff8882a945c000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000561fce3f9950 CR3: 000000016a658000 CR4: 00000000000006f0
DR0: ffff8880b8609000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <TASK>
 arch_stack_walk+0x11b/0x150
 stack_trace_save+0xa9/0x100
 save_stack+0x122/0x230
 __reset_page_owner+0x71/0x1f0
 __free_frozen_pages+0xc2b/0xdb0
 vfree+0x25a/0x400
 kcov_close+0x28/0x50
 __fput+0x44f/0xa70
 task_work_run+0x1d9/0x270
 do_exit+0x70f/0x23c0
 do_group_exit+0x21b/0x2d0
 get_signal+0x1284/0x1330
 arch_do_signal_or_restart+0xbc/0x830
 exit_to_user_mode_loop+0x86/0x480
 do_syscall_64+0x32d/0xf80
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f24ca79c799
Code: Unable to access opcode bytes at 0x7f24ca79c76f.
RSP: 002b:00007f24cb5950e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 00007f24caa16098 RCX: 00007f24ca79c799
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007f24caa16098
RBP: 00007f24caa16090 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f24caa16128 R14: 00007ffe49c59830 R15: 00007ffe49c59918
 </TASK>
