[PATCH v7 03/13] selftests/mm: restore default nr_hugepages value via exit trap in hugetlb_reparenting_test.sh

[Sayali Patil]

The test modifies nr_hugepages during execution and restores it from
cleanup() and again reconfigure it setup, which is invoked multiple
times across test flow. This can lead to repeated
allocation/freeing of hugepages.

With set -e, failures in cleanup (e.g., rmdir/umount) can also
cause early exit before restoring the original value at the end.

Move restoration of the original nr_hugepages value to a trap handler
registered for EXIT, INT, and TERM signals so it is always restored on
all exit paths. This also avoids unnecessary allocation churn across
repeated cleanup/setup cycles.

Fixes: 585a9145886a ("selftests/mm: restore default nr_hugepages value during cleanup in hugetlb_reparenting_test.sh")
Acked-by: Zi Yan <ziy@xxxxxxxxxx>
Tested-by: Venkat Rao Bagalkote <venkat88@xxxxxxxxxxxxx>
Signed-off-by: Sayali Patil <sayalip@xxxxxxxxxxxxx>
---
 tools/testing/selftests/mm/hugetlb_reparenting_test.sh | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/mm/hugetlb_reparenting_test.sh b/tools/testing/selftests/mm/hugetlb_reparenting_test.sh
index 0dd31892ff67..11f914831146 100755
--- a/tools/testing/selftests/mm/hugetlb_reparenting_test.sh
+++ b/tools/testing/selftests/mm/hugetlb_reparenting_test.sh
@@ -12,6 +12,8 @@ if [[ $(id -u) -ne 0 ]]; then
 fi
 
 nr_hugepgs=$(cat /proc/sys/vm/nr_hugepages)
+trap 'echo "$nr_hugepgs" > /proc/sys/vm/nr_hugepages' EXIT INT TERM
+
 usage_file=usage_in_bytes
 
 if [[ "$1" == "-cgroup-v2" ]]; then
@@ -56,7 +58,6 @@ function cleanup() {
   rmdir "$CGROUP_ROOT"/a/b 2>/dev/null
   rmdir "$CGROUP_ROOT"/a 2>/dev/null
   rmdir "$CGROUP_ROOT"/test1 2>/dev/null
-  echo $nr_hugepgs >/proc/sys/vm/nr_hugepages
   set -e
 }
 
@@ -240,4 +241,3 @@ if [[ $do_umount ]]; then
   rm -rf $CGROUP_ROOT
 fi
 
-echo "$nr_hugepgs" > /proc/sys/vm/nr_hugepages
-- 
2.52.0