6.6-stable review patch. If anyone has any objections, please let me know.
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From: Mark Brown broonie@kernel.org
commit 9c02223e2d9df5cb37c51aedb78f3960294e09b5 upstream.
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.
Link: https://lkml.kernel.org/r/20250404-kselftest-mm-cgroup2-detection-v1-1-3dba6... Fixes: 209376ed2a84 ("selftests/vm: make charge_reserved_hugetlb.sh work with existing cgroup setting") Signed-off-by: Mark Brown broonie@kernel.org Cc: Aishwarya TCV aishwarya.tcv@arm.com Cc: Mark Brown broonie@kernel.org Cc: Mina Almasry almasrymina@google.com Cc: Shuah Khan shuah@kernel.org Cc: Waiman Long longman@redhat.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.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(-)
--- a/tools/testing/selftests/mm/charge_reserved_hugetlb.sh +++ b/tools/testing/selftests/mm/charge_reserved_hugetlb.sh @@ -27,7 +27,7 @@ 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 @@ -35,7 +35,7 @@ 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 --- a/tools/testing/selftests/mm/hugetlb_reparenting_test.sh +++ b/tools/testing/selftests/mm/hugetlb_reparenting_test.sh @@ -22,7 +22,7 @@ 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