[PATCH v9 3/4] kselftest: mm: integrate huge page checks

[Yeoreum Yun <yeoreum.yun@arm.com>]

check_large_folios() only checks for large folios without distinguishing
between anonymous and file-backed huge pages.

To add huge page type checking, integrate the huge page checks into
__check_huge() and __check_type():

  1. If hpage_size == pmd_pagesize, check PAGE_IS_HUGE instead of using
     check_large_folios(), since only the mapping type matters. This
     identifies PMD-mapped huge pages.

  2. Otherwise, use check_large_folios() to detect large folios. This
     covers mTHP cases.

  3. Check the folio flags according to the huge page type via
     __check_type()

Suggested-by: David Hildenbrand (Arm) <david@kernel.org>
Suggested-by: Zi Yan <ziy@nvidia.com>
Signed-off-by: Yeoreum Yun <yeoreum.yun@arm.com>
---
 tools/testing/selftests/mm/vm_util.c | 90 ++++++++++++++++++++++--------------
 1 file changed, 56 insertions(+), 34 deletions(-)

diff --git a/tools/testing/selftests/mm/vm_util.c b/tools/testing/selftests/mm/vm_util.c
index a3c3a2706c22..65c06e17c326 100644
--- a/tools/testing/selftests/mm/vm_util.c
+++ b/tools/testing/selftests/mm/vm_util.c
@@ -392,76 +392,98 @@ static bool check_large_folios(void *addr, size_t len, int nr_hpages,
 	return ret;
 }
 
-enum check_huge_type {
-	CHECK_HUGE_ANON,
-	CHECK_HUGE_FILE,
+enum check_type {
+	CHECK_TYPE_ANON,
+	CHECK_TYPE_FILE,
 };
 
-static bool check_huge_type(uint64_t categories, enum check_huge_type type)
+static bool __check_type(void *addr, size_t len, uint64_t page_size,
+		enum check_type type)
 {
-	const bool file = categories & PAGE_IS_FILE;
+	bool ret = false;
+	int pagemap_fd;
+	char *start = addr;
+	char *end = start + len;
+	uint64_t categories;
 
-	switch (type) {
-	case CHECK_HUGE_ANON:
-		return !file;
-	case CHECK_HUGE_FILE:
-		return file;
+	pagemap_fd = open(PAGEMAP_PATH, O_RDONLY);
+	if (pagemap_fd < 0)
+		ksft_exit_fail_perror("open pagemap");
+
+	for (; start < end; start += page_size) {
+		categories = pagemap_scan_get_categories(pagemap_fd, start);
+		if ((categories & PAGE_IS_PRESENT) != PAGE_IS_PRESENT)
+			continue;
+
+		if ((type == CHECK_TYPE_FILE) != !!(categories & PAGE_IS_FILE))
+			goto out;
 	}
 
-	return false;
+	ret = true;
+
+out:
+	close(pagemap_fd);
+	return ret;
 }
 
-static bool __check_pmd_huge(void *addr, size_t len, int nr_hpages,
-		  uint64_t hpage_size, enum check_huge_type type)
+static bool __check_huge(void *addr, size_t len, int nr_hpages,
+		uint64_t hpage_size)
 {
+	bool ret = false;
 	int pagemap_fd;
 	int nr_pmd_mappings = 0;
+	uint64_t pmd_pagesize;
 	uint64_t categories;
 	char *start = addr;
 	char *end = start + len;
 
+	pmd_pagesize = read_pmd_pagesize();
+	if (!pmd_pagesize)
+		ksft_exit_fail_msg("reading PMD pagesize failed\n");
+
 	pagemap_fd = open(PAGEMAP_PATH, O_RDONLY);
 	if (pagemap_fd < 0)
 		ksft_exit_fail_perror("open pagemap");
 
+	if (hpage_size != pmd_pagesize) {
+		ret = check_large_folios(addr, len, nr_hpages, hpage_size);
+		goto out;
+	}
+
 	for (; start < end; start += hpage_size) {
 		categories = pagemap_scan_get_categories(pagemap_fd, start);
-		if (!(categories & PAGE_IS_HUGE))
-			continue;
-		if (check_huge_type(categories, type))
+		if (categories & PAGE_IS_HUGE)
 			nr_pmd_mappings++;
 	}
-	close(pagemap_fd);
 
-	return nr_hpages == nr_pmd_mappings;
+	if (nr_pmd_mappings != nr_hpages)
+		goto out;
+
+	ret = true;
+
+out:
+	close(pagemap_fd);
+	return ret;
 }
 
 bool check_huge_anon(void *addr, size_t len, int nr_hpages, uint64_t hpage_size)
 {
-	uint64_t pmd_pagesize = read_pmd_pagesize();
-
-	if (!pmd_pagesize)
-		ksft_exit_fail_msg("reading PMD pagesize failed\n");
+	const uint64_t scan_mapping_size = (nr_hpages > 0) ? hpage_size : psize();
 
-	if (hpage_size == pmd_pagesize)
-		return __check_pmd_huge(addr, len, nr_hpages, hpage_size,
-					CHECK_HUGE_ANON);
+	if (!__check_huge(addr, len, nr_hpages, hpage_size))
+		return false;
 
-	return check_large_folios(addr, len, nr_hpages, hpage_size);
+	return __check_type(addr, len, scan_mapping_size, CHECK_TYPE_ANON);
 }
 
 bool check_huge_file(void *addr, size_t len, int nr_hpages, uint64_t hpage_size)
 {
-	uint64_t pmd_pagesize = read_pmd_pagesize();
+	const uint64_t scan_mapping_size = (nr_hpages > 0) ? hpage_size : psize();
 
-	if (!pmd_pagesize)
-		ksft_exit_fail_msg("reading PMD pagesize failed\n");
-
-	if (hpage_size == pmd_pagesize)
-		return __check_pmd_huge(addr, len, nr_hpages, hpage_size,
-					CHECK_HUGE_FILE);
+	if (!__check_huge(addr, len, nr_hpages, hpage_size))
+		return false;
 
-	return check_large_folios(addr, len, nr_hpages, hpage_size);
+	return __check_type(addr, len, scan_mapping_size, CHECK_TYPE_FILE);
 }
 
 bool check_huge_shmem(void *addr, size_t len, int nr_hpages, uint64_t hpage_size)

-- 
2.43.0