INFO: task syz.3.771:8791 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.3.771       state:D stack:27272 pid:8791  tgid:8790  ppid:7462   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_version_get_doit+0x16e/0xb60
 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: 0033:0x7f7ca478ebe9
RSP: 002b:00007f7ca5676038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f7ca49b5fa0 RCX: 00007f7ca478ebe9
RDX: 0000000000040000 RSI: 0000200000000540 RDI: 0000000000000009
RBP: 00007f7ca4811e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f7ca49b6038 R14: 00007f7ca49b5fa0 R15: 00007ffdead9a058
 </TASK>
INFO: task syz.1.899:9206 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.1.899       state:D stack:25896 pid:9206  tgid:9205  ppid:5846   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_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: 0033:0x7fab0bf8ebe9
RSP: 002b:00007fab0cda9038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fab0c1b5fa0 RCX: 00007fab0bf8ebe9
RDX: 0000000000000000 RSI: 0000200000000040 RDI: 0000000000000009
RBP: 00007fab0c011e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fab0c1b6038 R14: 00007fab0c1b5fa0 R15: 00007ffe56daafe8
 </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 kswapd0/90:
2 locks held by getty/5666:
 #0: ffff888021ac50a0 (&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
2 locks held by syz.0.226/6750:
 #0: ffffffff8f59d230 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff8e4183c8 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_listener_set_doit+0x137/0x1690
2 locks held by syz.3.771/8791:
 #0: ffffffff8f59d230 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff8e4183c8 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_version_get_doit+0x16e/0xb60
2 locks held by syz.1.899/9206:
 #0: ffffffff8f59d230 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff8e4183c8 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_listener_set_doit+0x137/0x1690
2 locks held by syz.2.1413/11086:
 #0: ffffffff8f59d230 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff8e4183c8 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_listener_set_doit+0x137/0x1690
2 locks held by syz.4.1489/11342:
 #0: ffffffff8f59d230 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff8e4183c8 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_listener_set_doit+0x137/0x1690
1 lock held by syz-executor/11634:
2 locks held by syz.5.2029/13339:
 #0: ffffffff8f59d230 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff8e4183c8 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_listener_set_doit+0x137/0x1690
1 lock held by syz.8.2256/14199:
 #0: ffffffff8e13f938 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x3b9/0x730
2 locks held by syz.6.2257/14198:
 #0: ffffffff8fa54ef8 (&ops->srcu#2){.+.+}-{0:0}, at: rtnl_link_ops_get+0x23/0x250
 #1: ffffffff8e13f800 (rcu_state.barrier_mutex){+.+.}-{4:4}, at: rcu_barrier+0x4c/0x570

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

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: 14199 Comm: syz.8.2256 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:preempt_count_add+0x42/0x1a0
Code: ab 99 48 c1 e8 03 42 0f b6 04 38 84 c0 0f 85 f1 00 00 00 83 3d 4e 97 1b 18 00 75 07 65 8b 05 55 44 10 11 65 01 3d 4e 44 10 11 <48> c7 c0 20 93 ab 99 48 c1 e8 03 42 0f b6 04 38 84 c0 0f 85 ec 00
RSP: 0018:ffffc900074b7880 EFLAGS: 00000282
RAX: 0000000080000001 RBX: 0000000000000001 RCX: ffffffff99ab9303
RDX: 0000000000000017 RSI: ffffffff8be332e0 RDI: 0000000000000001
RBP: 0000000000000000 R08: dffffc0000000000 R09: 0000000000000000
R10: ffffed100d1a9400 R11: fffffbfff1f46fc7 R12: ffffffff8dbded10
R13: ffff88804b03fe80 R14: ffff88804b03fe80 R15: dffffc0000000000
FS:  00007f2132a146c0(0000) GS:ffff8880b861c000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f2bd9bf8440 CR3: 000000000df36000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 _raw_spin_trylock+0x19/0x80
 __free_frozen_pages+0x65e/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: 0033:0x7f2131b8ebe9
Code: Unable to access opcode bytes at 0x7f2131b8ebbf.
RSP: 002b:00007f2132a14038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffa1 RBX: 00007f2131db6090 RCX: 00007f2131b8ebe9
RDX: 0000200000000240 RSI: 00000000000089f1 RDI: 0000000000000003
RBP: 00007f2131c11e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f2131db6128 R14: 00007f2131db6090 R15: 00007ffe6b9f8038
 </TASK>
