[PATCH v2 1/2] selftests/mm: on-fault-limit: run test without root privileges otherwise skip

[Muhammad Usama Anjum]

The mmap() respects rlimit only for normal users. This test should be
run as normal user, without root privileges. Also add back the sudo -u
nobody as run_vmtests.sh is run as root most of the times. Skip the test
instead if sudo isn't present to lower the privileges.

Fixes: b6221771d468 ("selftests/mm: run_vmtests: remove sudo and conform to tap")
Signed-off-by: Muhammad Usama Anjum <usama.anjum@xxxxxxxxxxxxx>
---
Please fold this patch in the Fixes patch if needed.
---
 tools/testing/selftests/mm/on-fault-limit.c | 6 +++---
 tools/testing/selftests/mm/run_vmtests.sh   | 7 ++++++-
 2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/tools/testing/selftests/mm/on-fault-limit.c b/tools/testing/selftests/mm/on-fault-limit.c
index 0ea98ffab3589..431c1277d83a1 100644
--- a/tools/testing/selftests/mm/on-fault-limit.c
+++ b/tools/testing/selftests/mm/on-fault-limit.c
@@ -21,7 +21,7 @@ static void test_limit(void)
 	map = mmap(NULL, 2 * lims.rlim_max, PROT_READ | PROT_WRITE,
 		   MAP_PRIVATE | MAP_ANONYMOUS | MAP_POPULATE, -1, 0);
 
-	ksft_test_result(map == MAP_FAILED, "Failed mmap\n");
+	ksft_test_result(map == MAP_FAILED, "The map failed respecting mlock limits\n");
 
 	if (map != MAP_FAILED)
 		munmap(map, 2 * lims.rlim_max);
@@ -33,8 +33,8 @@ int main(int argc, char **argv)
 	ksft_print_header();
 	ksft_set_plan(1);
 
-	if (getuid())
-		ksft_test_result_skip("Require root privileges to run\n");
+	if (!getuid())
+		ksft_test_result_skip("The test must be run from a normal user\n");
 	else
 		test_limit();
 
diff --git a/tools/testing/selftests/mm/run_vmtests.sh b/tools/testing/selftests/mm/run_vmtests.sh
index 55898d64e2ebf..edd73f871c79a 100755
--- a/tools/testing/selftests/mm/run_vmtests.sh
+++ b/tools/testing/selftests/mm/run_vmtests.sh
@@ -303,7 +303,12 @@ echo "$nr_hugepgs" > /proc/sys/vm/nr_hugepages
 
 CATEGORY="compaction" run_test ./compaction_test
 
-CATEGORY="mlock" run_test ./on-fault-limit
+if command -v sudo &> /dev/null;
+then
+	CATEGORY="mlock" run_test sudo -u nobody ./on-fault-limit
+else
+	echo "# SKIP ./on-fault-limit"
+fi
 
 CATEGORY="mmap" run_test ./map_populate
 
-- 
2.42.0