[PATCH v1 RESEND 1/6] selftests/mm: reuse read_pmd_pagesize() in COW selftest

[David Hildenbrand <david@xxxxxxxxxx>]

The COW selftest can deal with THP not being configured. So move error
handling of read_pmd_pagesize() into the callers such that we can reuse
it in the COW selftest.

Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
---
 tools/testing/selftests/mm/cow.c              | 33 +++----------------
 tools/testing/selftests/mm/khugepaged.c       |  4 +++
 tools/testing/selftests/mm/soft-dirty.c       |  3 ++
 .../selftests/mm/split_huge_page_test.c       |  4 +++
 tools/testing/selftests/mm/vm_util.c          |  4 +--
 5 files changed, 17 insertions(+), 31 deletions(-)

diff --git a/tools/testing/selftests/mm/cow.c b/tools/testing/selftests/mm/cow.c
index 0eb2e8180aa5..dc9d6fe86028 100644
--- a/tools/testing/selftests/mm/cow.c
+++ b/tools/testing/selftests/mm/cow.c
@@ -45,34 +45,6 @@ static size_t hugetlbsizes[10];
 static int gup_fd;
 static bool has_huge_zeropage;
 
-static void detect_thpsize(void)
-{
-	int fd = open("/sys/kernel/mm/transparent_hugepage/hpage_pmd_size",
-		      O_RDONLY);
-	size_t size = 0;
-	char buf[15];
-	int ret;
-
-	if (fd < 0)
-		return;
-
-	ret = pread(fd, buf, sizeof(buf), 0);
-	if (ret > 0 && ret < sizeof(buf)) {
-		buf[ret] = 0;
-
-		size = strtoul(buf, NULL, 10);
-		if (size < pagesize)
-			size = 0;
-		if (size > 0) {
-			thpsize = size;
-			ksft_print_msg("[INFO] detected THP size: %zu KiB\n",
-				       thpsize / 1024);
-		}
-	}
-
-	close(fd);
-}
-
 static void detect_huge_zeropage(void)
 {
 	int fd = open("/sys/kernel/mm/transparent_hugepage/use_zero_page",
@@ -1741,7 +1713,10 @@ int main(int argc, char **argv)
 	int err;
 
 	pagesize = getpagesize();
-	detect_thpsize();
+	thpsize = read_pmd_pagesize();
+	if (thpsize)
+		ksft_print_msg("[INFO] detected THP size: %zu KiB\n",
+			       thpsize / 1024);
 	detect_hugetlbsizes();
 	detect_huge_zeropage();
 
diff --git a/tools/testing/selftests/mm/khugepaged.c b/tools/testing/selftests/mm/khugepaged.c
index 64126c8cd561..97adc0f34f9c 100644
--- a/tools/testing/selftests/mm/khugepaged.c
+++ b/tools/testing/selftests/mm/khugepaged.c
@@ -1476,6 +1476,10 @@ int main(int argc, const char **argv)
 
 	page_size = getpagesize();
 	hpage_pmd_size = read_pmd_pagesize();
+	if (!hpage_pmd_size) {
+		printf("Reading PMD pagesize failed");
+		exit(EXIT_FAILURE);
+	}
 	hpage_pmd_nr = hpage_pmd_size / page_size;
 
 	default_settings.khugepaged.max_ptes_none = hpage_pmd_nr - 1;
diff --git a/tools/testing/selftests/mm/soft-dirty.c b/tools/testing/selftests/mm/soft-dirty.c
index 21d8830c5f24..cc5f144430d4 100644
--- a/tools/testing/selftests/mm/soft-dirty.c
+++ b/tools/testing/selftests/mm/soft-dirty.c
@@ -80,6 +80,9 @@ static void test_hugepage(int pagemap_fd, int pagesize)
 	int i, ret;
 	size_t hpage_len = read_pmd_pagesize();
 
+	if (!hpage_len)
+		ksft_exit_fail_msg("Reading PMD pagesize failed");
+
 	map = memalign(hpage_len, hpage_len);
 	if (!map)
 		ksft_exit_fail_msg("memalign failed\n");
diff --git a/tools/testing/selftests/mm/split_huge_page_test.c b/tools/testing/selftests/mm/split_huge_page_test.c
index 76e1c36dd9e5..1dc5804b8b2b 100644
--- a/tools/testing/selftests/mm/split_huge_page_test.c
+++ b/tools/testing/selftests/mm/split_huge_page_test.c
@@ -300,6 +300,10 @@ int main(int argc, char **argv)
 	pagesize = getpagesize();
 	pageshift = ffs(pagesize) - 1;
 	pmd_pagesize = read_pmd_pagesize();
+	if (!pmd_pagesize) {
+		printf("Reading PMD pagesize failed\n");
+		exit(EXIT_FAILURE);
+	}
 
 	split_pmd_thp();
 	split_pte_mapped_thp();
diff --git a/tools/testing/selftests/mm/vm_util.c b/tools/testing/selftests/mm/vm_util.c
index 40e795624ff3..8dc74dd022c2 100644
--- a/tools/testing/selftests/mm/vm_util.c
+++ b/tools/testing/selftests/mm/vm_util.c
@@ -84,12 +84,12 @@ uint64_t read_pmd_pagesize(void)
 
 	fd = open(PMD_SIZE_FILE_PATH, O_RDONLY);
 	if (fd == -1)
-		ksft_exit_fail_msg("Open hpage_pmd_size failed\n");
+		return 0;
 
 	num_read = read(fd, buf, 19);
 	if (num_read < 1) {
 		close(fd);
-		ksft_exit_fail_msg("Read hpage_pmd_size failed\n");
+		return 0;
 	}
 	buf[num_read] = '\0';
 	close(fd);
-- 
2.39.2