Currently if the filesystem for the cgroups version it wants to use is not mounted charge_reserved_hugetlb.sh and hugetlb_reparenting_test.sh tests will attempt to mount it on the hard coded path /dev/cgroup/memory, deleting that directory when the test finishes. This will fail if there is not a preexisting directory at that path, and since the directory is deleted subsequent runs of the test will fail. Instead of relying on this hard coded directory name use mktemp to generate a temporary directory to use as a mountpoint, fixing both the assumption and the disruption caused by deleting a preexisting directory.
This means that if the relevant cgroup filesystem is not already mounted then we rely on having coreutils (which provides mktemp) installed. I suspect that many current users are relying on having things automounted by default, and given that the script relies on bash it's probably not an unreasonable requirement.
Fixes: 209376ed2a84 ("selftests/vm: make charge_reserved_hugetlb.sh work with existing cgroup setting") Signed-off-by: Mark Brown broonie@kernel.org --- tools/testing/selftests/mm/charge_reserved_hugetlb.sh | 4 ++-- tools/testing/selftests/mm/hugetlb_reparenting_test.sh | 2 +- 2 files changed, 3 insertions(+), 3 deletions(-)
diff --git a/tools/testing/selftests/mm/charge_reserved_hugetlb.sh b/tools/testing/selftests/mm/charge_reserved_hugetlb.sh index 67df7b47087f..e1fe16bcbbe8 100755 --- a/tools/testing/selftests/mm/charge_reserved_hugetlb.sh +++ b/tools/testing/selftests/mm/charge_reserved_hugetlb.sh @@ -29,7 +29,7 @@ fi if [[ $cgroup2 ]]; then cgroup_path=$(mount -t cgroup2 | head -1 | awk '{print $3}') if [[ -z "$cgroup_path" ]]; then - cgroup_path=/dev/cgroup/memory + cgroup_path=$(mktemp -d) mount -t cgroup2 none $cgroup_path do_umount=1 fi @@ -37,7 +37,7 @@ if [[ $cgroup2 ]]; then else cgroup_path=$(mount -t cgroup | grep ",hugetlb" | awk '{print $3}') if [[ -z "$cgroup_path" ]]; then - cgroup_path=/dev/cgroup/memory + cgroup_path=$(mktemp -d) mount -t cgroup memory,hugetlb $cgroup_path do_umount=1 fi diff --git a/tools/testing/selftests/mm/hugetlb_reparenting_test.sh b/tools/testing/selftests/mm/hugetlb_reparenting_test.sh index 11f9bbe7dc22..0b0d4ba1af27 100755 --- a/tools/testing/selftests/mm/hugetlb_reparenting_test.sh +++ b/tools/testing/selftests/mm/hugetlb_reparenting_test.sh @@ -23,7 +23,7 @@ fi if [[ $cgroup2 ]]; then CGROUP_ROOT=$(mount -t cgroup2 | head -1 | awk '{print $3}') if [[ -z "$CGROUP_ROOT" ]]; then - CGROUP_ROOT=/dev/cgroup/memory + CGROUP_ROOT=$(mktemp -d) mount -t cgroup2 none $CGROUP_ROOT do_umount=1 fi
--- base-commit: a4cda136f021ad44b8b52286aafd613030a6db5f change-id: 20250403-kselftest-mm-cgroup2-detection-b761fd232f9d
Best regards,