+ kselftest-mm-integrate-huge-page-checks.patch added to mm-new branch

+ kselftest-mm-integrate-huge-page-checks.patch added to mm-new branch

[Andrew Morton]

The patch titled
     Subject: kselftest: mm: integrate huge page checks
has been added to the -mm mm-new branch.  Its filename is
     kselftest-mm-integrate-huge-page-checks.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/kselftest-mm-integrate-huge-page-checks.patch

This patch will later appear in the mm-new branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Note, mm-new is a provisional staging ground for work-in-progress
patches, and acceptance into mm-new is a notification for others take
notice and to finish up reviews.  Please do not hesitate to respond to
review feedback and post updated versions to replace or incrementally
fixup patches in mm-new.

The mm-new branch of mm.git is not included in linux-next

If a few days of testing in mm-new is successful, the patch will me moved
into mm.git's mm-unstable branch, which is included in linux-next

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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

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and is updated there most days

------------------------------------------------------
From: Yeoreum Yun <yeoreum.yun@arm.com>
Subject: kselftest: mm: integrate huge page checks
Date: Thu, 24 Sep 2026 20:11:18 +0100

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():

  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.

Link: https://lore.kernel.org/20260924-fix_split-v8-3-cba7359d882a@arm.com
Signed-off-by: Yeoreum Yun <yeoreum.yun@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Suggested-by: David Hildenbrand (Arm) <david@kernel.org>
Suggested-by: Zi Yan <ziy@nvidia.com>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Nico Pache <nico.pache@linux.dev>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Usama Arif <usama.arif@linux.dev>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Kevin Brodsky <kevin.brodsky@arm.com>
---

 tools/testing/selftests/mm/vm_util.c |   90 +++++++++++++------------
 1 file changed, 48 insertions(+), 42 deletions(-)

--- a/tools/testing/selftests/mm/vm_util.c~kselftest-mm-integrate-huge-page-checks
+++ a/tools/testing/selftests/mm/vm_util.c
@@ -351,13 +351,13 @@ err_out:
 	return entry;
 }
 
-static bool check_large_folios(void *addr, size_t len, int nr_hpages,
+static bool check_large_folios(int pagemap_fd, int kpageflags_fd,
+		void *addr, size_t len, int nr_hpages,
 		uint64_t hpage_size)
 {
 	int order = 0, pagesize = getpagesize();
 	unsigned int nr_pages = hpage_size / pagesize;
 	int orders[MAX_NR_ORDERS], status;
-	int pagemap_fd, kpageflags_fd;
 	bool ret = false;
 
 	if (!nr_pages)
@@ -368,15 +368,6 @@ static bool check_large_folios(void *add
 		ksft_exit_fail_msg("invalid order\n");
 
 	memset(orders, 0, sizeof(int) * MAX_NR_ORDERS);
-	pagemap_fd = open(PAGEMAP_PATH, O_RDONLY);
-	if (pagemap_fd == -1)
-		ksft_exit_fail_msg("read pagemap fail\n");
-
-	kpageflags_fd = open(KPAGEFLAGS_PATH, O_RDONLY);
-	if (kpageflags_fd == -1) {
-		close(pagemap_fd);
-		ksft_exit_fail_msg("read kpageflags fail\n");
-	}
 
 	status = gather_folio_orders(addr, len, pagemap_fd,
 			kpageflags_fd, orders, MAX_NR_ORDERS);
@@ -387,8 +378,6 @@ static bool check_large_folios(void *add
 		ret = true;
 
 out:
-	close(pagemap_fd);
-	close(kpageflags_fd);
 	return ret;
 }
 
@@ -411,57 +400,74 @@ static bool check_huge_type(uint64_t cat
 	return false;
 }
 
-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, enum check_huge_type type)
 {
-	int pagemap_fd;
+	bool ret = false;
+	int pagemap_fd, kpageflags_fd;
 	int nr_pmd_mappings = 0;
+	uint64_t pmd_pagesize, scan_mapping_size;
 	uint64_t categories;
+	unsigned long pfn;
+	bool check_pmd_mapping, allow_nonpresent;
 	char *start = addr;
 	char *end = start + len;
 
+	pmd_pagesize = read_pmd_pagesize();
+	if (!pmd_pagesize)
+		ksft_exit_fail_msg("reading PMD pagesize failed\n");
+
+	check_pmd_mapping = hpage_size == pmd_pagesize;
+	scan_mapping_size = (nr_hpages > 0) ? hpage_size : psize();
+	/* Some mTHP tests check a partially populated PMD-sized range. */
+	allow_nonpresent = (uint64_t)nr_hpages * hpage_size < len;
+
 	pagemap_fd = open(PAGEMAP_PATH, O_RDONLY);
 	if (pagemap_fd < 0)
 		ksft_exit_fail_msg("open pagemap fail\n");
 
-	for (; start < end; start += hpage_size) {
+	kpageflags_fd = open(KPAGEFLAGS_PATH, O_RDONLY);
+	if (kpageflags_fd < 0)
+		ksft_exit_fail_msg("open kpageflags fail\n");
+
+	if (!check_pmd_mapping &&
+	    !check_large_folios(pagemap_fd, kpageflags_fd,
+				addr, len, nr_hpages, hpage_size))
+		goto out;
+
+	for (; start < end; start += scan_mapping_size) {
 		categories = pagemap_scan_get_categories(pagemap_fd, start);
-		if (!(categories & PAGE_IS_HUGE))
-			continue;
-		if (check_huge_type(categories, type))
+		pfn = pagemap_get_pfn(pagemap_fd, start);
+		if (pfn == -1UL) {
+			if (!allow_nonpresent)
+				goto out;
+			else
+				continue;
+		}
+		if (check_pmd_mapping && (categories & PAGE_IS_HUGE))
 			nr_pmd_mappings++;
+		if (!check_huge_type(categories, type))
+			goto out;
 	}
-	close(pagemap_fd);
 
-	return nr_hpages == nr_pmd_mappings;
+	if (check_pmd_mapping && (nr_pmd_mappings != nr_hpages))
+		goto out;
+	ret = true;
+
+out:
+	close(pagemap_fd);
+	close(kpageflags_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");
-
-	if (hpage_size == pmd_pagesize)
-		return __check_pmd_huge(addr, len, nr_hpages, hpage_size,
-					CHECK_HUGE_ANON);
-
-	return check_large_folios(addr, len, nr_hpages, hpage_size);
+	return __check_huge(addr, len, nr_hpages, hpage_size, CHECK_HUGE_ANON);
 }
 
 bool check_huge_file(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");
-
-	if (hpage_size == pmd_pagesize)
-		return __check_pmd_huge(addr, len, nr_hpages, hpage_size,
-					CHECK_HUGE_FILE);
-
-	return check_large_folios(addr, len, nr_hpages, hpage_size);
+	return __check_huge(addr, len, nr_hpages, hpage_size, CHECK_HUGE_FILE);
 }
 
 bool check_huge_shmem(void *addr, size_t len, int nr_hpages, uint64_t hpage_size)
_

Patches currently in -mm which might be from yeoreum.yun@arm.com are

kselftest-mm-fix-potential-failure-for-merged-vma-in-guard-regions.patch
kselftest-mm-remove-exclusion-of-building-soft-dirty-test-in-arm64.patch
kselftest-mm-return-fail-when-child-test-result-is-fail-in-khugepaged.patch
kselftest-mm-fix-intermittent-failure-khugepaged-test.patch
kselftest-mm-prevent-random-failure-of-huge-page-split-for-khugepaged.patch
kselftest-mm-replace-usage-of-proc-self-smaps-for-__check_pmd_huge.patch
kselftest-mm-integrate-huge-page-checks.patch
kselftest-mm-remove-check_huge_shmem.patch