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From: Muhammad Usama Anjum <usama.anjum@collabora.com>
To: Andrew Morton <akpm@linux-foundation.org>,
	Shuah Khan <shuah@kernel.org>
Cc: Muhammad Usama Anjum <usama.anjum@collabora.com>,
	kernel@collabora.com,
	Ryan Roberts <ryan.roberts@arm.com>,
	linux-mm@kvack.org,
	linux-kselftest@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: [PATCH v3 3/5] selftests/mm: save and restore nr_hugepages value
Date: Thu, 25 Jan 2024 20:46:06 +0500
Message-ID: <20240125154608.720072-4-usama.anjum@collabora.com>
In-Reply-To: <20240125154608.720072-1-usama.anjum@collabora.com>
References: <20240125154608.720072-1-usama.anjum@collabora.com>
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Save and restore nr_hugepages before changing it during the test. A test
should not change system wide settings.

Signed-off-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
---
 tools/testing/selftests/mm/charge_reserved_hugetlb.sh  | 4 ++++
 tools/testing/selftests/mm/hugetlb_reparenting_test.sh | 3 +++
 2 files changed, 7 insertions(+)

diff --git a/tools/testing/selftests/mm/charge_reserved_hugetlb.sh b/tools/testing/selftests/mm/charge_reserved_hugetlb.sh
index e14bdd4455f2d..d680c00d2853a 100755
--- a/tools/testing/selftests/mm/charge_reserved_hugetlb.sh
+++ b/tools/testing/selftests/mm/charge_reserved_hugetlb.sh
@@ -11,6 +11,8 @@ if [[ $(id -u) -ne 0 ]]; then
   exit $ksft_skip
 fi
 
+nr_hugepgs=$(cat /proc/sys/vm/nr_hugepages)
+
 fault_limit_file=limit_in_bytes
 reservation_limit_file=rsvd.limit_in_bytes
 fault_usage_file=usage_in_bytes
@@ -582,3 +584,5 @@ if [[ $do_umount ]]; then
   umount $cgroup_path
   rmdir $cgroup_path
 fi
+
+echo "$nr_hugepgs" > /proc/sys/vm/nr_hugepages
diff --git a/tools/testing/selftests/mm/hugetlb_reparenting_test.sh b/tools/testing/selftests/mm/hugetlb_reparenting_test.sh
index 615c4d766c909..11f9bbe7dc222 100755
--- a/tools/testing/selftests/mm/hugetlb_reparenting_test.sh
+++ b/tools/testing/selftests/mm/hugetlb_reparenting_test.sh
@@ -11,6 +11,7 @@ if [[ $(id -u) -ne 0 ]]; then
   exit $ksft_skip
 fi
 
+nr_hugepgs=$(cat /proc/sys/vm/nr_hugepages)
 usage_file=usage_in_bytes
 
 if [[ "$1" == "-cgroup-v2" ]]; then
@@ -252,3 +253,5 @@ if [[ $do_umount ]]; then
   umount $CGROUP_ROOT
   rm -rf $CGROUP_ROOT
 fi
+
+echo "$nr_hugepgs" > /proc/sys/vm/nr_hugepages
-- 
2.42.0