selftests/mm: run_vmtests: remove sudo and conform to tap

Remove sudo as some test running environments may not have sudo available.
Instead skip the test if root privileges aren't available in the test.

[[e-mail]: on-fault-limit: run test without root privileges otherwise skip]
Link: https://lkml.kernel.org/r/[e-mail]
Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Muhammad Usama Anjum <[e-mail]>
Cc: Ryan Roberts <[e-mail]>
Cc: Shuah Khan <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>

tools/testing/selftests/mm/on-fault-limit.c

···
 #include <string.h>
 #include <sys/time.h>
 #include <sys/resource.h>
+#include "../kselftest.h"
 
-static int test_limit(void)
+static void test_limit(void)
 {
-	int ret = 1;
 	struct rlimit lims;
 	void *map;
 
-	if (getrlimit(RLIMIT_MEMLOCK, &lims)) {
-		perror("getrlimit");
-		return ret;
-	}
+	if (getrlimit(RLIMIT_MEMLOCK, &lims))
+		ksft_exit_fail_msg("getrlimit: %s\n", strerror(errno));
 
-	if (mlockall(MCL_ONFAULT | MCL_FUTURE)) {
-		perror("mlockall");
-		return ret;
-	}
+	if (mlockall(MCL_ONFAULT | MCL_FUTURE))
+		ksft_exit_fail_msg("mlockall: %s\n", strerror(errno));
 
 	map = mmap(NULL, 2 * lims.rlim_max, PROT_READ | PROT_WRITE,
 		   MAP_PRIVATE | MAP_ANONYMOUS | MAP_POPULATE, -1, 0);
-	if (map != MAP_FAILED)
-		printf("mmap should have failed, but didn't\n");
-	else {
-		ret = 0;
-		munmap(map, 2 * lims.rlim_max);
-	}
 
+	ksft_test_result(map == MAP_FAILED, "The map failed respecting mlock limits\n");
+
+	if (map != MAP_FAILED)
+		munmap(map, 2 * lims.rlim_max);
 	munlockall();
-	return ret;
 }
 
 int main(int argc, char **argv)
 {
-	int ret = 0;
+	ksft_print_header();
+	ksft_set_plan(1);
 
-	ret += test_limit();
-	return ret;
+	if (!getuid())
+		ksft_test_result_skip("The test must be run from a normal user\n");
+	else
+		test_limit();
+
+	ksft_finished();
 }

tools/testing/selftests/mm/run_vmtests.sh

···
 
 CATEGORY="compaction" run_test ./compaction_test
 
-CATEGORY="mlock" run_test sudo -u nobody ./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