From 607723b13a0cdfb9ea4da6edb819f0b496e0d133 Mon Sep 17 00:00:00 2001 From: Mark Brown Date: Fri, 4 Apr 2025 17:42:32 +0100 Subject: [PATCH] selftests/mm: generate a temporary mountpoint for cgroup filesystem 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-v1-1-3dba6d32ba8c@kernel.org Fixes: 209376ed2a84 ("selftests/vm: make charge_reserved_hugetlb.sh work with existing cgroup setting") Signed-off-by: Mark Brown Cc: Aishwarya TCV Cc: Mark Brown Cc: Mina Almasry Cc: Shuah Khan Cc: Waiman Long Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman --- 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 8e00276b4e69b..dc3fc438b3d9e 100755 --- 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 diff --git a/tools/testing/selftests/mm/hugetlb_reparenting_test.sh b/tools/testing/selftests/mm/hugetlb_reparenting_test.sh index 14d26075c8635..302f2c7003f03 100755 --- 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