From dd9b35efd719be242e227f9eebad1e50ea5c914f Mon Sep 17 00:00:00 2001
From: Breno Leitao <leitao@debian.org>
Date: Fri, 3 Nov 2023 10:33:59 -0700
Subject: [PATCH] selftests/mm: restore number of hugepages
The test mm `hugetlb_fault_after_madv` selftest needs one and only one
huge page to run, thus it sets `/proc/sys/vm/nr_hugepages` to 1.
The problem is that further tests require the previous number of hugepages
allocated in order to succeed.
Save the number of huge pages before changing it, and restore it once the
test finishes, so, further tests could run successfully.
Link: https://lkml.kernel.org/r/20231103173400.1608403-1-leitao@debian.org
Fixes: 116d57303a05 ("selftests/mm: add a new test for madv and hugetlb")
Signed-off-by: Breno Leitao <leitao@debian.org>
Reported-by: Ryan Roberts <ryan.roberts@arm.com>
Closes: https://lore.kernel.org/all/662df57e-47f1-4c15-9b84-f2f2d587fc5c@arm.com/
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
tools/testing/selftests/mm/run_vmtests.sh | 3 +++
1 file changed, 3 insertions(+)
diff --git a/tools/testing/selftests/mm/run_vmtests.sh b/tools/testing/selftests/mm/run_vmtests.sh
index cc16f6ca85333..00757445278ed 100755
--- a/tools/testing/selftests/mm/run_vmtests.sh
+++ b/tools/testing/selftests/mm/run_vmtests.sh
@@ -223,9 +223,12 @@ CATEGORY="hugetlb" run_test ./hugepage-mremap
CATEGORY="hugetlb" run_test ./hugepage-vmemmap
CATEGORY="hugetlb" run_test ./hugetlb-madvise
+nr_hugepages_tmp=$(cat /proc/sys/vm/nr_hugepages)
# For this test, we need one and just one huge page
echo 1 > /proc/sys/vm/nr_hugepages
CATEGORY="hugetlb" run_test ./hugetlb_fault_after_madv
+# Restore the previous number of huge pages, since further tests rely on it
+echo "$nr_hugepages_tmp" > /proc/sys/vm/nr_hugepages
if test_selected "hugetlb"; then
echo "NOTE: These hugetlb tests provide minimal coverage. Use"