INFO: task syz.0.9746:28835 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.9746      state:D stack:25864 pid:28835 tgid:28834 ppid:5850   task_flags:0x400140 flags:0x00004004
Call Trace:
 <TASK>
 __schedule+0x1798/0x4cc0
 schedule+0x165/0x360
 schedule_preempt_disabled+0x13/0x30
 __mutex_lock+0x7e6/0x1350
 nfsd_nl_listener_set_doit+0x137/0x1690
 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: 0033:0x7f645838ec29
RSP: 002b:00007f645925e038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f64585d5fa0 RCX: 00007f645838ec29
RDX: 0000000000000000 RSI: 0000200000000040 RDI: 0000000000000006
RBP: 00007f6458411e41 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f64585d6038 R14: 00007f64585d5fa0 R15: 00007ffe183c4898
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/34:
 #0: ffffffff8e13a0e0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
2 locks held by getty/5677:
 #0: ffff888021dd10a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70
 #1: ffffc900029062f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x43e/0x1400
2 locks held by sshd/5792:
3 locks held by syz.2.6185/20483:
1 lock held by syz-executor/20991:
 #0: ffffffff8e13fb78 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x3b9/0x730
2 locks held by syz.3.8786/26555:
 #0: ffffffff8f5a08d0 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff8e418b48 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_listener_set_doit+0x137/0x1690
2 locks held by syz.0.9746/28835:
 #0: ffffffff8f5a08d0 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff8e418b48 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_listener_set_doit+0x137/0x1690
2 locks held by syz.6.10053/29560:
 #0: ffffffff8f5a08d0 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff8e418b48 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_listener_set_doit+0x137/0x1690
1 lock held by syz.7.11950/1647:
 #0: ffffffff8e13fb78 (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+0x439/0x7d0
 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: 1634 Comm: syz.5.11944 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:__kasan_check_byte+0x12/0x40
Code: cf fe ff ff 0f 1f 40 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 66 0f 1f 00 41 56 53 48 89 f3 49 89 fe e8 5e 14 00 00 <84> c0 75 16 be 01 00 00 00 4c 89 f7 31 d2 48 89 d9 89 c3 e8 c6 03
RSP: 0018:ffffc9000659f480 EFLAGS: 00000293
RAX: 0000000000000001 RBX: ffffffff8172c1b2 RCX: b8b337712d2a7b00
RDX: 0000000000000000 RSI: ffffffff8172c1b2 RDI: 1ffffffff1c2741c
RBP: ffffffff8172c195 R08: 0000000000000000 R09: 0000000000000000
R10: ffffc9000659f658 R11: ffffffff81ac3c30 R12: 0000000000000002
R13: ffffffff8e13a0e0 R14: ffffffff8e13a0e0 R15: 0000000000000000
FS:  000055556b716500(0000) GS:ffff8881a3c39000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000559ec146a043 CR3: 000000000df36000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 lock_acquire+0x8d/0x360
 unwind_next_frame+0xc2/0x2390
 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: 0033:0x7fcfe91c14e5
Code: Unable to access opcode bytes at 0x7fcfe91c14bb.
RSP: 002b:00007ffd0d49f130 EFLAGS: 00000293 ORIG_RAX: 00000000000000e6
RAX: 0000000000000000 RBX: 00007fcfe93d5fa0 RCX: 00007fcfe91c14e5
RDX: 00007ffd0d49f170 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007fcfe93d7da0 R08: 0000000000000000 R09: 7fffffffffffffff
R10: 0000000000000000 R11: 0000000000000293 R12: 00000000000b7deb
R13: 00007ffd0d49f290 R14: ffffffffffffffff R15: 00007ffd0d49f2b0
 </TASK>
