Comment 0 for bug 2075275

Found on Jammy 6.8 variants since 2024.04.29:
  * J-oracle-6.8.0-1006.6~22.04.3 (2024.04.29)
  * J-azure-6.8.0-1008.8~22.04.1 (2024.04.29)
  * J-aws-6.8.0-1009.9~22.04.2 (2024.04.29)
  * J-gcp-6.8.0-1010.11~22.04.1 (2024.06.10)
  * J-hwe-6.8.0-38.38~22.04.1 (2024.06.10)
  * J-ibm-6.8.0-1008.8~22.04.1 (2024.06.10)
  * J-lowlatency-hwe-6.8.0-38.38.1~22.04.2 (2024.06.10)
  * J-nvidia-6.8.0-1009.9~22.04.1 (2024.06.10)
  * J-realtime-6.8.1-1004.4~22.04.1 (2024.06.10)

When trying to run the memfd test in ubuntu_kernel_selftests, the run_hugetlbfs_test.sh sub-test will have a leftover process the prevents the test to finish properly, and consequently causing sut-test failure in our infrastructure.

$ cd ~/autotest/client/tmp/ubuntu_kernel_selftests/src/linux/tools/testing/selftests/
$ sudo make TARGETS=memfd
$ cd memfd
$ sudo ./run_hugetlbfs_test.sh
memfd-hugetlb: CREATE
memfd-hugetlb: BASIC
memfd-hugetlb: SEAL-EXEC
memfd-hugetlb: Apply SEAL_EXEC
fchmod(/memfd:kern_memfd_seal_exec (deleted), 00777) didn't fail as expected
./run_hugetlbfs_test.sh: line 60: 1424 Aborted (core dumped) ./memfd_test hugetlbfs
fusermount: failed to unmount /home/ubuntu/autotest/client/tmp/ubuntu_kernel_selftests/src/linux/tools/testing/selftests/memfd/mnt: Invalid argument
eopening: ./mnt/memfd
cho $?ADD_SEALS(4, 0 -> 8) failed: Device or resource busy
8 != 0 = GET_SEALS(4)
Aborted (core dumped)
$ echo $?
0
$ ps aux | grep fuse
root 1431 0.0 0.0 150776 1292 ? Ssl 01:50 0:00 ./fuse_mnt ./mnt
ubuntu 1454 0.0 0.0 7008 2304 pts/0 S+ 01:50 0:00 grep --color=auto fuse

Nothing interesting in dmesg output.