INFO: task syz.4.7068:24162 blocked for more than 143 seconds.
      Tainted: G             L      syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.4.7068      state:D stack:26696 pid:24162 tgid:24158 ppid:23110  task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 __schedule+0x15dd/0x52d0
 schedule+0x164/0x360
 schedule_preempt_disabled+0x13/0x30
 __mutex_lock+0x7fe/0x1300
 nfsd_shutdown_threads+0x4e/0xd0
 nfsd_umount+0x41/0x60
 deactivate_locked_super+0xbc/0x130
 cleanup_mnt+0x437/0x4d0
 task_work_run+0x1d9/0x270
 exit_to_user_mode_loop+0xed/0x480
 do_syscall_64+0x32d/0xf80
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f49f879c819
RSP: 002b:00007f49f69b4028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffec RBX: 00007f49f8a16180 RCX: 00007f49f879c819
RDX: 0000200000000040 RSI: 00002000000001c0 RDI: 0000000000000000
RBP: 00007f49f8832c91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000001000016 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f49f8a16218 R14: 00007f49f8a16180 R15: 00007fffee9115f8
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/34:
 #0: ffffffff8e75e620 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
4 locks held by udevd/5811:
2 locks held by getty/6660:
 #0: ffff8881135e30a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70
 #1: ffffc900066722f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45c/0x13c0
2 locks held by syz.5.5783/20434:
 #0: ffffffff8fc3f4b0 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff8ea87928 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_threads_set_doit+0x2b5/0x9a0
2 locks held by kworker/u10:4/23876:
 #0: ffff88823c63ade0 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x31/0x150
 #1: ffff88823c624588 (psi_seq){-.-.}-{0:0}, at: psi_task_switch+0x53/0x880
2 locks held by syz-executor/23902:
 #0: ffff88811d0680e0 (&type->s_umount_key#100){++++}-{4:4}, at: deactivate_super+0xa9/0xe0
 #1: ffffffff8ebeea48 (jfs_log_mutex){+.+.}-{4:4}, at: lmLogClose+0xb4/0x520
2 locks held by syz.4.7068/24162:
 #0: ffff88810ef220e0 (&type->s_umount_key#137){+.+.}-{4:4}, at: deactivate_super+0xa9/0xe0
 #1: ffffffff8ea87928 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x4e/0xd0

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

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 34 Comm: khungtaskd Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
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: 0 Comm: swapper/1 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:pv_native_safe_halt+0xf/0x20
Code: 1e 6f 02 c3 cc cc cc cc cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa eb 07 0f 00 2d e3 23 1d 00 fb f4 <e9> 7c e7 02 00 cc cc cc cc cc cc cc cc cc cc cc cc 90 90 90 90 90
RSP: 0018:ffffc90000197e20 EFLAGS: 00000206
RAX: 0000000000a0f6db RBX: ffffffff819a857a RCX: 0000000080000001
RDX: 0000000000000001 RSI: ffffffff8defc9db RDI: ffffffff8c27f880
RBP: ffffc90000197f10 R08: ffff88823c63399b R09: 1ffff110478c6733
R10: dffffc0000000000 R11: ffffed10478c6734 R12: 0000000000000001
R13: 1ffff1102c08e000 R14: 0000000000000001 R15: 1ffff1102c08e000
FS:  0000000000000000(0000) GS:ffff8882a9462000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f8c8dde92f8 CR3: 000000016b35c000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 default_idle+0x9/0x20
 default_idle_call+0x72/0xb0
 do_idle+0x36a/0x5f0
 cpu_startup_entry+0x43/0x60
 start_secondary+0x101/0x110
 common_startup_64+0x13e/0x147
 </TASK>
