INFO: task syz.0.1308:8934 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.1308      state:D stack:26824 pid:8934  tgid:8933  ppid:5617   task_flags:0x400040 flags:0x00080002
Call Trace:
 <TASK>
 __schedule+0x17b4/0x5680
 schedule+0x164/0x360
 schedule_preempt_disabled+0x13/0x30
 __mutex_lock+0x7f7/0x1550
 nfsd_nl_listener_get_doit+0x10a/0x5e0
 genl_family_rcv_msg_doit+0x22a/0x330
 genl_rcv_msg+0x61c/0x7a0
 netlink_rcv_skb+0x232/0x4b0
 genl_rcv+0x28/0x40
 netlink_unicast+0x75c/0x8e0
 netlink_sendmsg+0x813/0xb40
 ____sys_sendmsg+0x972/0x9f0
 ___sys_sendmsg+0x2a5/0x360
 __x64_sys_sendmsg+0x1bd/0x2a0
 do_syscall_64+0x15f/0xf80
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f060dd9cdd9
RSP: 002b:00007f060ece7028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f060e015fa0 RCX: 00007f060dd9cdd9
RDX: 0000000004000000 RSI: 0000200000000100 RDI: 0000000000000003
RBP: 00007f060de32d69 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f060e016038 R14: 00007f060e015fa0 R15: 00007ffcf8c70258
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/34:
 #0: ffffffff8e95cd60 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
2 locks held by getty/5439:
 #0: ffff888175bae0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70
 #1: ffffc900034732e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45c/0x13a0
6 locks held by kworker/u11:3/5619:
 #0: ffff888170a76940 ((wq_completion)hci3){+.+.}-{0:0}, at: process_scheduled_works+0xa35/0x1860
 #1: ffffc9000454fc40 ((work_completion)(&hdev->cmd_sync_work)){+.+.}-{0:0}, at: process_scheduled_works+0xa70/0x1860
 #2: ffff88816c578ea0 (&hdev->req_lock){+.+.}-{4:4}, at: hci_cmd_sync_work+0x1d3/0x400
 #3: ffff88816c5780b8 (&hdev->lock){+.+.}-{4:4}, at: hci_abort_conn_sync+0xa6f/0x1190
 #4: ffffffff8ff53580 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_conn_failed+0x165/0x340
 #5: ffff8881143502f8 (&conn->lock#2){+.+.}-{4:4}, at: l2cap_conn_del+0x92/0x570
2 locks held by syz.1.662/7410:
 #0: ffffffff8fe3f9c8 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff8ec8aca0 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_listener_set_doit+0x141/0x1670
2 locks held by syz.0.1308/8934:
 #0: ffffffff8fe3f9c8 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff8ec8aca0 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_listener_get_doit+0x10a/0x5e0
1 lock held by syz-executor/9490:
 #0: ffffffff8e963068 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x38d/0x770
2 locks held by syz.2.3411/13959:
 #0: ffffffff8fe3f9c8 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff8ec8aca0 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_listener_set_doit+0x141/0x1670

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

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+0xe8/0x150
 nmi_cpu_backtrace+0x274/0x2d0
 nmi_trigger_cpumask_backtrace+0x17a/0x300
 sys_info+0x135/0x170
 watchdog+0xfd3/0x1030
 kthread+0x388/0x470
 ret_from_fork+0x514/0xb70
 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: 16085 Comm: syz.5.4294 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:check_preemption_disabled+0x2a/0xe0
Code: 55 41 57 41 56 53 65 8b 05 b7 af 8f 07 65 8b 0d ac af 8f 07 f7 c1 ff ff ff 7f 74 0c 5b 41 5e 41 5f 5d e9 09 d7 02 00 cc 9c 59 <f7> c1 00 02 00 00 74 ea 65 4c 8b 3d 5e af 8f 07 41 f6 47 2f 04 74
RSP: 0018:ffffc9000634f930 EFLAGS: 00000046
RAX: 0000000000000001 RBX: ffff88823c53cfe0 RCX: 0000000000000046
RDX: 0000000000000000 RSI: ffffffff8c28adc0 RDI: ffffffff8c28ad80
RBP: 1ffff110478c77ee R08: ffffffff9030dcf7 R09: 1ffffffff2061b9e
R10: dffffc0000000000 R11: fffffbfff2061b9f R12: dffffc0000000000
R13: ffff88823c63bf70 R14: ffff88823c63be80 R15: ffff88823c6339d8
FS:  00007f480e1bb6c0(0000) GS:ffff8882a9287000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fcff8087e20 CR3: 000000000e74a000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 call_rcu+0x5b9/0x890
 kmem_cache_free+0x462/0x650
 task_work_run+0x1d9/0x270
 do_exit+0x70f/0x22c0
 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+0x33e/0xf80
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f480d39cdd9
Code: Unable to access opcode bytes at 0x7f480d39cdaf.
RSP: 002b:00007f480e1bb0e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 00007f480d616188 RCX: 00007f480d39cdd9
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007f480d616188
RBP: 00007f480d616180 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f480d616218 R14: 00007ffc35dc8d10 R15: 00007ffc35dc8df8
 </TASK>
