[LTP] [issue] cgroup: fail to mount, if mount immediately after umount

[Ma Xinjian]

Hi guys,

I ran the LTP case "cgroup cgroup_regression_test.sh" on Cento10,
and found that if mounting cgroup immediately after umount, it will report 
error "cgroup already mounted or mount point busy."

But this does not occur on old kernel(such as Centos9).
Could someone help take a look?

Reproduce Step:
```
# mkdir cgroup
# mount -t cgroup -o none,name=foo cgroup cgroup
# umount cgroup && mount -t cgroup -o none,name=foo cgroup cgroup
mount: /opt/ltp/tmpdir/cgroup: cgroup already mounted or mount point busy.
       dmesg(1) may have more information after failed mount system call.
```

LTP failed case:
```
Running tests.......                                                                                                                                                                                                                                                                                                          
<<<test_start>>>
tag=cgroup stime=1735584666
cmdline="cgroup_regression_test.sh"
contacts=""
analysis=exit
<<<test_output>>>
incrementing stop
cgroup_regression_test 1 TINFO: Running: cgroup_regression_test.sh 
cgroup_regression_test 1 TINFO: Tested kernel: Linux  6.11.0-0.rc5.23.el10.x86_64 #1 SMP PREEMPT_DYNAMIC Mon Sep 23 04:19:12 EDT 2024 x86_64 GNU/Linux
cgroup_regression_test 1 TINFO: Using /tmp/ltp-q3TtUTWV42/LTP_cgroup_regression_test.68LuGosjOZ as tmpdir (xfs filesystem)
cgroup_regression_test 1 TINFO: timeout per run is 0h 5m 0s
cgroup_regression_test 1 TPASS: no kernel bug was found
mount: /tmp/ltp-q3TtUTWV42/LTP_cgroup_regression_test.68LuGosjOZ/cgroup: cgroup already mounted or mount point busy.
       dmesg(1) may have more information after failed mount system call.
cgroup_regression_test 2 TFAIL: Failed to mount cgroup filesystem
cgroup_regression_test 3 TCONF: CONFIG_SCHED_DEBUG is not enabled
cgroup_regression_test 4 TCONF: CONFIG_LOCKDEP is not enabled
cgroup_regression_test 5 TINFO: The '/tmp/ltp-q3TtUTWV42/LTP_cgroup_regression_test.68LuGosjOZ/cgroup' is not mounted, skipping umount
cgroup_regression_test 5 TPASS: no kernel bug was found
cgroup_regression_test 6 TPASS: no kernel bug was found
cgroup_regression_test 7 TPASS: no kernel bug was found for test 1
cgroup_regression_test 7 TCONF: skip rest of testing due possible oops triggered by reading /proc/sched_debug
cgroup_regression_test 7 TPASS: no kernel bug was found for test 2
cgroup_regression_test 8 TPASS: no kernel bug was found

Summary:
passed   6
failed   1
broken   0
skipped  3
warnings 0
<<<execution_status>>>
initiation_status="ok"
duration=62 termination_type=exited termination_id=1 corefile=no
cutime=4420 cstime=7914
<<<test_end>>>
INFO: ltp-pan reported some tests FAIL
LTP Version: 20240524-400-gec81cf213
```

Best regards
Ma