linux-kernel - [PATCH v4 12/12] selftests/mm/mlock: Print error on failure

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Message-ID: <20250311-mm-selftests-v4-12-dec210a658f5@google.com>
Date: Tue, 11 Mar 2025 13:18:23 +0000
From: Brendan Jackman <jackmanb@...gle.com>
To: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>, Andrew Morton <akpm@...ux-foundation.org>, 
	Shuah Khan <shuah@...nel.org>
Cc: Dev Jain <dev.jain@....com>, linux-mm@...ck.org, linux-kselftest@...r.kernel.org, 
	linux-kernel@...r.kernel.org, Brendan Jackman <jackmanb@...gle.com>
Subject: [PATCH v4 12/12] selftests/mm/mlock: Print error on failure

It's not really possible to start diagnosing this without knowing the
actual error.

Also update the mlock2 helper to behave like libc would by setting errno
and returning -1.

Signed-off-by: Brendan Jackman <jackmanb@...gle.com>
---
 tools/testing/selftests/mm/mlock-random-test.c | 4 ++--
 tools/testing/selftests/mm/mlock2.h            | 8 +++++++-
 2 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/tools/testing/selftests/mm/mlock-random-test.c b/tools/testing/selftests/mm/mlock-random-test.c
index 1cd80b0f76c33f04ef01f4dee6602f28b6a7c991..b8d7e966f44c67e5606d384bd660e5a4e5e8fda9 100644
--- a/tools/testing/selftests/mm/mlock-random-test.c
+++ b/tools/testing/selftests/mm/mlock-random-test.c
@@ -161,9 +161,9 @@ static void test_mlock_within_limit(char *p, int alloc_size)
 				       MLOCK_ONFAULT);
 
 		if (ret)
-			ksft_exit_fail_msg("%s() failure at |%p(%d)| mlock:|%p(%d)|\n",
+			ksft_exit_fail_msg("%s() failure (%s) at |%p(%d)| mlock:|%p(%d)|\n",
 					   is_mlock ? "mlock" : "mlock2",
-					   p, alloc_size,
+					   strerror(errno), p, alloc_size,
 					   p + start_offset, lock_size);
 	}
 
diff --git a/tools/testing/selftests/mm/mlock2.h b/tools/testing/selftests/mm/mlock2.h
index 4417eaa5cfb78ba2bb0f51d3418c9b768ff0fe90..81e77fa41901a095cc041e05d01da7dffbf2f4fe 100644
--- a/tools/testing/selftests/mm/mlock2.h
+++ b/tools/testing/selftests/mm/mlock2.h
@@ -6,7 +6,13 @@
 
 static int mlock2_(void *start, size_t len, int flags)
 {
-	return syscall(__NR_mlock2, start, len, flags);
+	int ret = syscall(__NR_mlock2, start, len, flags);
+
+	if (ret) {
+		errno = ret;
+		return -1;
+	}
+	return 0;
 }
 
 static FILE *seek_to_smaps_entry(unsigned long addr)

-- 
2.49.0.rc0.332.g42c0ae87b1-goog