The patch below does not apply to the 5.10-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.10.y git checkout FETCH_HEAD git cherry-pick -x 9c02223e2d9df5cb37c51aedb78f3960294e09b5 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2025042145-carmaker-turbofan-c6eb@gregkh' --subject-prefix 'PATCH 5.10.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 9c02223e2d9df5cb37c51aedb78f3960294e09b5 Mon Sep 17 00:00:00 2001 From: Mark Brown broonie@kernel.org Date: Fri, 4 Apr 2025 17:42:32 +0100 Subject: [PATCH] selftests/mm: generate a temporary mountpoint for cgroup filesystem

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

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