[PATCH v2 2/3] selftests/mm: alloc hugepages in va_high_addr_switch test

[Chunyu Hu <chuhu@redhat.com>]

Alloc hugepages in the test internally, so we don't fully rely on the
run_vmtests.sh. If run_vmtests.sh does that great, free hugepages is
enough for being used to run the test, leave it as it is, otherwise setup
the hugepages in the test.

Save the original nr_hugepages value and restore it after test finish, so
leave a stable test envronment.

Signed-off-by: Chunyu Hu <chuhu@redhat.com>
---
 .../selftests/mm/va_high_addr_switch.sh       | 37 +++++++++++++++++++
 1 file changed, 37 insertions(+)

diff --git a/tools/testing/selftests/mm/va_high_addr_switch.sh b/tools/testing/selftests/mm/va_high_addr_switch.sh
index 325de53966b6..a7d4b02b21dd 100755
--- a/tools/testing/selftests/mm/va_high_addr_switch.sh
+++ b/tools/testing/selftests/mm/va_high_addr_switch.sh
@@ -9,6 +9,7 @@
 
 # Kselftest framework requirement - SKIP code is 4.
 ksft_skip=4
+orig_nr_hugepages=0
 
 skip()
 {
@@ -76,5 +77,41 @@ check_test_requirements()
 	esac
 }
 
+save_nr_hugepages()
+{
+	orig_nr_hugepages=$(cat /proc/sys/vm/nr_hugepages)
+}
+
+restore_nr_hugepages()
+{
+	echo "$orig_nr_hugepages" > /proc/sys/vm/nr_hugepages
+}
+
+setup_nr_hugepages()
+{
+	local needpgs=$1
+	while read -r name size unit; do
+		if [ "$name" = "HugePages_Free:" ]; then
+			freepgs="$size"
+			break
+		fi
+	done < /proc/meminfo
+	if [ "$freepgs" -ge "$needpgs" ]; then
+		return
+	fi
+	local hpgs=$((orig_nr_hugepages + needpgs))
+	echo $hpgs > /proc/sys/vm/nr_hugepages
+
+	local nr_hugepgs=$(cat /proc/sys/vm/nr_hugepages)
+	if [ "$nr_hugepgs" != "$hpgs" ]; then
+		restore_nr_hugepages
+		skip "$0: no enough hugepages for testing"
+	fi
+}
+
 check_test_requirements
+save_nr_hugepages
+# 4 keep_mapped pages, and one for tmp usage
+setup_nr_hugepages 5
 ./va_high_addr_switch --run-hugetlb
+restore_nr_hugepages
-- 
2.49.0