[PATCH v4 0/3] kselftest: mm: remove HPAGE_SIZE and HPAGE_SHIFT macro

[PATCH v4 0/3] kselftest: mm: remove HPAGE_SIZE and HPAGE_SHIFT macro

[Yeoreum Yun]

HPAGE_SIZE and HPAGE_SHIFT macro is written based on the 4KB PAGE_SIZE.
When this macro is used in some test, test result would be strange in
the system where PAGE_SIZE is more then 4KB.

Here is the example with transhuge-stress test with 16KB PAGE_SIZE:

  transhuge-stress: allocate 61073 transhuge pages, using 122146 MiB virtual memory and 1908 MiB of ram
    3.292 s/loop, 0.054 ms/page,  37106.002 MiB/s       2566 succeed, 58507 failed, 2566 different pages
    0.591 s/loop, 0.010 ms/page, 206850.792 MiB/s          0 succeed, 61073 failed,    0 different pages
    0.527 s/loop, 0.009 ms/page, 231895.107 MiB/s          0 succeed, 61073 failed,    0 different pages
    3.292 s/loop, 0.054 ms/page,  37106.002 MiB/s       2566 succeed, 58507 failed, 2566 different pages
    0.591 s/loop, 0.010 ms/page, 206850.792 MiB/s          0 succeed, 61073 failed,    0 different pages
    0.527 s/loop, 0.009 ms/page, 231895.107 MiB/s          0 succeed, 61073 failed,    0 different pages
    0.527 s/loop, 0.009 ms/page, 231839.704 MiB/s          0 succeed, 61073 failed,    0 different pages
    0.528 s/loop, 0.009 ms/page, 231544.782 MiB/s          0 succeed, 61073 failed,    0 different pages
    0.528 s/loop, 0.009 ms/page, 231462.074 MiB/s          0 succeed, 61073 failed,    0 different pages
    0.527 s/loop, 0.009 ms/page, 231770.300 MiB/s          0 succeed, 61073 failed,    0 different pages
    ...
  ok 1 Completed

To address this, remove the HPAGE_SIZE and HPAGE_SHIFT macro,
introduce pmd_pshift() and rename read_pmd_pagesize() to pmd_psize()
to keep consistency with psize() and pshift().

Also, run the KSM_MERGE_TIME_HUGE_PAGES test with a size of 512 MiB,
which is the least common multiple of the PMD sizes for 4 KiB, 16 KiB,
and 64 KiB base pages. Since allocate_transhuge() allocates mappings in
PMD-sized units, the test may fail with the previous size of 100 MiB,
which is not a multiple of the PMD size when the base page size is
16 KiB or 64 KiB.

After this patch, output of transhuge-stress:

  transhuge-stress: allocate 3817 transhuge pages, using 122146 MiB virtual memory and 119 MiB of ram
    2.558 s/loop, 0.670 ms/page,  47755.759 MiB/s       2585 succeed, 1232 failed, 2585 different pages
    2.640 s/loop, 0.692 ms/page,  46268.432 MiB/s       2585 succeed, 1232 failed, 2585 different pages
    2.635 s/loop, 0.690 ms/page,  46360.298 MiB/s       2585 succeed, 1232 failed, 2585 different pages
    2.782 s/loop, 0.729 ms/page,  43899.795 MiB/s       2616 succeed, 1201 failed, 2616 different pages
    2.692 s/loop, 0.705 ms/page,  45380.876 MiB/s       2627 succeed, 1190 failed, 2627 different pages
    2.612 s/loop, 0.684 ms/page,  46765.812 MiB/s       2628 succeed, 1189 failed, 2628 different pages
    2.683 s/loop, 0.703 ms/page,  45520.990 MiB/s       2630 succeed, 1187 failed, 2630 different pages
    2.727 s/loop, 0.714 ms/page,  44789.321 MiB/s       2631 succeed, 1186 failed, 2631 different pages
    ...
  ok 1 Completed

Additionally, introduce size_to_shift() for future users that need to
obtain shift of a huge-page which is other than pmd_psize().

Patch History
=============
Changes in v4:
  - make size_to_shift() as inline function.
  - initialise __pmd_psize and __pmd_pshift with -1ull.
  - Link to v3: https://lore.kernel.org/r/20260914-fix_hpage_macro-v3-0-c9a305a01d39@arm.com

Change in v3:
 - rename read_pmd_pagesize() to pmd_psize()
 - introduce size_to_shift()
 - Link to v2: https://lore.kernel.org/all/20260907081509.924979-1-yeoreum.yun@arm.com/

Chnage in v2:
 - rename hpage_* to pmd_page_*
 - Link to v1: https://lore.kernel.org/all/20260902175611.1241118-1-yeoreum.yun@arm.com/#t

---
Yeoreum Yun (3):
      kselftest: mm: rename read_pmd_pagesize() to pmd_psize()
      kselftest: mm: remove HPAGE_SIZE and HPAGE_SHIFT macro
      kselftest: mm: introduce size_to_shift() helper

 tools/testing/selftests/mm/cow.c                   |  2 +-
 tools/testing/selftests/mm/folio_split_race_test.c |  2 +-
 tools/testing/selftests/mm/guard-regions.c         | 11 +++++-
 tools/testing/selftests/mm/hmm-tests.c             | 22 +++++------
 tools/testing/selftests/mm/khugepaged.c            |  2 +-
 tools/testing/selftests/mm/ksm_tests.c             | 16 +++++---
 tools/testing/selftests/mm/migration.c             |  4 +-
 tools/testing/selftests/mm/mkdirty.c               |  2 +-
 tools/testing/selftests/mm/pagemap_ioctl.c         |  2 +-
 tools/testing/selftests/mm/prctl_thp_disable.c     |  4 +-
 tools/testing/selftests/mm/process_madv.c          |  2 +-
 tools/testing/selftests/mm/run_vmtests.sh          |  4 +-
 tools/testing/selftests/mm/soft-dirty.c            |  2 +-
 tools/testing/selftests/mm/split_huge_page_test.c  |  2 +-
 tools/testing/selftests/mm/transhuge-stress.c      | 25 +++++++-----
 tools/testing/selftests/mm/uffd-common.c           |  6 +--
 tools/testing/selftests/mm/uffd-unit-tests.c       |  8 ++--
 tools/testing/selftests/mm/uffd-wp-mremap.c        |  2 +-
 tools/testing/selftests/mm/vm_util.c               | 46 +++++++++++++++++-----
 tools/testing/selftests/mm/vm_util.h               | 23 +++++++----
 20 files changed, 120 insertions(+), 67 deletions(-)
---
base-commit: 8d61431ed2607386b427752505379536eb634ce8
change-id: 20260909-fix_hpage_macro-da069ae04502

Best regards,
-- 
Sincerely,
Yeoreum Yun

[PATCH v4 1/3] kselftest: mm: rename read_pmd_pagesize() to pmd_psize()

[Yeoreum Yun]

For consistency with psize(), rename read_pmd_pagesize() to
pmd_psize(). There is no functional change.

Suggested-by: David Hildenbrand (Arm) <david@kernel.org>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Signed-off-by: Yeoreum Yun <yeoreum.yun@arm.com>
---
 tools/testing/selftests/mm/cow.c                   |  2 +-
 tools/testing/selftests/mm/folio_split_race_test.c |  2 +-
 tools/testing/selftests/mm/hmm-tests.c             | 22 +++++++++++-----------
 tools/testing/selftests/mm/khugepaged.c            |  2 +-
 tools/testing/selftests/mm/migration.c             |  4 ++--
 tools/testing/selftests/mm/mkdirty.c               |  2 +-
 tools/testing/selftests/mm/pagemap_ioctl.c         |  2 +-
 tools/testing/selftests/mm/prctl_thp_disable.c     |  4 ++--
 tools/testing/selftests/mm/process_madv.c          |  2 +-
 tools/testing/selftests/mm/soft-dirty.c            |  2 +-
 tools/testing/selftests/mm/split_huge_page_test.c  |  2 +-
 tools/testing/selftests/mm/uffd-common.c           |  6 +++---
 tools/testing/selftests/mm/uffd-unit-tests.c       |  8 ++++----
 tools/testing/selftests/mm/uffd-wp-mremap.c        |  2 +-
 tools/testing/selftests/mm/vm_util.c               |  8 ++++----
 tools/testing/selftests/mm/vm_util.h               |  2 +-
 16 files changed, 36 insertions(+), 36 deletions(-)

diff --git a/tools/testing/selftests/mm/cow.c b/tools/testing/selftests/mm/cow.c
index 8aa5249d9bef6..e42edeccfd7a2 100644
--- a/tools/testing/selftests/mm/cow.c
+++ b/tools/testing/selftests/mm/cow.c
@@ -1889,7 +1889,7 @@ int main(int argc, char **argv)
 	thp_save_settings();
 
 	pagesize = getpagesize();
-	pmdsize = read_pmd_pagesize();
+	pmdsize = pmd_psize();
 	if (pmdsize) {
 		/* Only if THP is supported. */
 		thp_read_settings(&default_settings);
diff --git a/tools/testing/selftests/mm/folio_split_race_test.c b/tools/testing/selftests/mm/folio_split_race_test.c
index 1960635a953eb..a956e5c74c655 100644
--- a/tools/testing/selftests/mm/folio_split_race_test.c
+++ b/tools/testing/selftests/mm/folio_split_race_test.c
@@ -235,7 +235,7 @@ int main(void)
 	ksft_print_header();
 
 	page_size = getpagesize();
-	pmd_pagesize = read_pmd_pagesize();
+	pmd_pagesize = pmd_psize();
 
 	if (!thp_available() || !pmd_pagesize)
 		ksft_exit_skip("Transparent Hugepages not available\n");
diff --git a/tools/testing/selftests/mm/hmm-tests.c b/tools/testing/selftests/mm/hmm-tests.c
index e2642eca0d02b..ad14372b75d9e 100644
--- a/tools/testing/selftests/mm/hmm-tests.c
+++ b/tools/testing/selftests/mm/hmm-tests.c
@@ -569,7 +569,7 @@ TEST_F(hmm, anon_write_child)
 
 	for (migrate = 0; migrate < 2; ++migrate) {
 		for (use_thp = 0; use_thp < 2; ++use_thp) {
-			npages = ALIGN(use_thp ? read_pmd_pagesize() : HMM_BUFFER_SIZE,
+			npages = ALIGN(use_thp ? pmd_psize() : HMM_BUFFER_SIZE,
 				       self->page_size) >> self->page_shift;
 			ASSERT_NE(npages, 0);
 			size = npages << self->page_shift;
@@ -730,7 +730,7 @@ TEST_F(hmm, anon_write_huge)
 	int *ptr;
 	int ret;
 
-	size = 2 * read_pmd_pagesize();
+	size = 2 * pmd_psize();
 
 	buffer = hmm_buffer_alloc(size, size,
 				  PROT_READ | PROT_WRITE,
@@ -1941,7 +1941,7 @@ TEST_F(hmm, migrate_anon_huge_empty)
 	int *ptr;
 	int ret;
 
-	size = read_pmd_pagesize();
+	size = pmd_psize();
 
 	buffer = hmm_buffer_alloc(2 * size, size,
 				  PROT_READ,
@@ -1984,7 +1984,7 @@ TEST_F(hmm, migrate_anon_huge_zero)
 	int ret;
 	int val;
 
-	size = read_pmd_pagesize();
+	size = pmd_psize();
 
 	buffer = hmm_buffer_alloc(2 * size, size,
 				  PROT_READ,
@@ -2038,7 +2038,7 @@ TEST_F(hmm, migrate_anon_huge_free)
 	int *ptr;
 	int ret;
 
-	size = read_pmd_pagesize();
+	size = pmd_psize();
 
 	buffer = hmm_buffer_alloc(2 * size, size,
 				  PROT_READ | PROT_WRITE,
@@ -2091,7 +2091,7 @@ TEST_F(hmm, migrate_anon_huge_fault)
 	int *ptr;
 	int ret;
 
-	size = read_pmd_pagesize();
+	size = pmd_psize();
 
 	buffer = hmm_buffer_alloc(2 * size, size,
 				  PROT_READ | PROT_WRITE,
@@ -2161,7 +2161,7 @@ TEST_F(hmm, migrate_partial_unmap_fault)
 {
 	struct hmm_buffer *buffer;
 	unsigned long npages;
-	unsigned long size = read_pmd_pagesize();
+	unsigned long size = pmd_psize();
 	unsigned long unmap_size;
 	unsigned long offsets[3];
 	unsigned long i;
@@ -2226,7 +2226,7 @@ TEST_F(hmm, migrate_remap_fault)
 {
 	struct hmm_buffer *buffer;
 	unsigned long npages;
-	unsigned long size = read_pmd_pagesize();
+	unsigned long size = pmd_psize();
 	unsigned long offsets[3];
 	unsigned long i;
 	void *old_ptr, *new_ptr = NULL;
@@ -2323,7 +2323,7 @@ TEST_F(hmm, migrate_anon_huge_err)
 	int *ptr;
 	int ret;
 
-	size = read_pmd_pagesize();
+	size = pmd_psize();
 
 	buffer = hmm_buffer_alloc(2 * size, 2 * size,
 				  PROT_READ | PROT_WRITE,
@@ -2413,7 +2413,7 @@ TEST_F(hmm, migrate_anon_huge_zero_err)
 	int *ptr;
 	int ret;
 
-	size = read_pmd_pagesize();
+	size = pmd_psize();
 
 	buffer = hmm_buffer_alloc(2 * size, 2 * size,
 				  PROT_READ,
@@ -2609,7 +2609,7 @@ static inline int run_migration_benchmark(int fd, int use_thp, size_t buffer_siz
 TEST_F_TIMEOUT(hmm, benchmark_thp_migration, 120)
 {
 	struct benchmark_results thp_results, regular_results;
-	size_t thp_size = read_pmd_pagesize();
+	size_t thp_size = pmd_psize();
 	int iterations = 5;
 
 	if (!thp_size)
diff --git a/tools/testing/selftests/mm/khugepaged.c b/tools/testing/selftests/mm/khugepaged.c
index f82673f5f6b47..76c1fbcc5260d 100644
--- a/tools/testing/selftests/mm/khugepaged.c
+++ b/tools/testing/selftests/mm/khugepaged.c
@@ -1330,7 +1330,7 @@ int main(int argc, char **argv)
 		ksft_exit_skip("Transparent Hugepages not available\n");
 
 	page_size = getpagesize();
-	hpage_pmd_size = read_pmd_pagesize();
+	hpage_pmd_size = pmd_psize();
 	if (!hpage_pmd_size)
 		ksft_exit_fail_msg("Reading PMD pagesize failed\n");
 	hpage_pmd_nr = hpage_pmd_size / page_size;
diff --git a/tools/testing/selftests/mm/migration.c b/tools/testing/selftests/mm/migration.c
index f19d53c695764..4280d2c87b22a 100644
--- a/tools/testing/selftests/mm/migration.c
+++ b/tools/testing/selftests/mm/migration.c
@@ -229,7 +229,7 @@ TEST_F_TIMEOUT(migration, private_anon_thp, 2*RUNTIME)
 	if (!thp_is_enabled())
 		SKIP(return, "Transparent Hugepages not available");
 
-	pmdsize = read_pmd_pagesize();
+	pmdsize = pmd_psize();
 	if (!pmdsize)
 		SKIP(return, "Reading PMD pagesize failed");
 
@@ -263,7 +263,7 @@ TEST_F_TIMEOUT(migration, shared_anon_thp, 2*RUNTIME)
 	if (!thp_is_enabled())
 		SKIP(return, "Transparent Hugepages not available");
 
-	pmdsize = read_pmd_pagesize();
+	pmdsize = pmd_psize();
 	if (!pmdsize)
 		SKIP(return, "Reading PMD pagesize failed");
 
diff --git a/tools/testing/selftests/mm/mkdirty.c b/tools/testing/selftests/mm/mkdirty.c
index 68dd447a54542..49ef643a6e639 100644
--- a/tools/testing/selftests/mm/mkdirty.c
+++ b/tools/testing/selftests/mm/mkdirty.c
@@ -330,7 +330,7 @@ int main(void)
 	int err, tests = 2;
 
 	pagesize = getpagesize();
-	thpsize = read_pmd_pagesize();
+	thpsize = pmd_psize();
 	if (thpsize) {
 		ksft_print_msg("[INFO] detected THP size: %zu KiB\n",
 			       thpsize / 1024);
diff --git a/tools/testing/selftests/mm/pagemap_ioctl.c b/tools/testing/selftests/mm/pagemap_ioctl.c
index d9a4fb782ecfe..d0e34dd5850b1 100644
--- a/tools/testing/selftests/mm/pagemap_ioctl.c
+++ b/tools/testing/selftests/mm/pagemap_ioctl.c
@@ -1654,7 +1654,7 @@ int main(int __attribute__((unused)) argc, char *argv[])
 	ksft_print_header();
 
 	page_size = getpagesize();
-	hpage_size = read_pmd_pagesize();
+	hpage_size = pmd_psize();
 
 	if (init_uffd())
 		ksft_exit_skip("Failed to initialize userfaultfd\n");
diff --git a/tools/testing/selftests/mm/prctl_thp_disable.c b/tools/testing/selftests/mm/prctl_thp_disable.c
index 82c6e96ea6eb3..d0290c4567bd9 100644
--- a/tools/testing/selftests/mm/prctl_thp_disable.c
+++ b/tools/testing/selftests/mm/prctl_thp_disable.c
@@ -133,7 +133,7 @@ FIXTURE_SETUP(prctl_thp_disable_completely)
 	if (!thp_available())
 		SKIP(return, "Transparent Hugepages not available\n");
 
-	self->pmdsize = read_pmd_pagesize();
+	self->pmdsize = pmd_psize();
 	if (!self->pmdsize)
 		SKIP(return, "Unable to read PMD size\n");
 
@@ -241,7 +241,7 @@ FIXTURE_SETUP(prctl_thp_disable_except_madvise)
 	if (!thp_available())
 		SKIP(return, "Transparent Hugepages not available\n");
 
-	self->pmdsize = read_pmd_pagesize();
+	self->pmdsize = pmd_psize();
 	if (!self->pmdsize)
 		SKIP(return, "Unable to read PMD size\n");
 
diff --git a/tools/testing/selftests/mm/process_madv.c b/tools/testing/selftests/mm/process_madv.c
index 3fffd5f7e6fb4..7e32bad8ab2a9 100644
--- a/tools/testing/selftests/mm/process_madv.c
+++ b/tools/testing/selftests/mm/process_madv.c
@@ -141,7 +141,7 @@ TEST_F(process_madvise, remote_collapse)
 		void *map_addr;
 	} info;
 
-	huge_page_size = read_pmd_pagesize();
+	huge_page_size = pmd_psize();
 	if (huge_page_size <= 0)
 		SKIP(return, "Could not determine a valid huge page size.\n");
 
diff --git a/tools/testing/selftests/mm/soft-dirty.c b/tools/testing/selftests/mm/soft-dirty.c
index 5f278913c4d75..670fcad083b58 100644
--- a/tools/testing/selftests/mm/soft-dirty.c
+++ b/tools/testing/selftests/mm/soft-dirty.c
@@ -88,7 +88,7 @@ static void test_hugepage(int pagemap_fd, int pagesize)
 		return;
 	}
 
-	size_t hpage_len = read_pmd_pagesize();
+	size_t hpage_len = pmd_psize();
 	if (!hpage_len)
 		ksft_exit_fail_msg("Reading PMD pagesize failed");
 
diff --git a/tools/testing/selftests/mm/split_huge_page_test.c b/tools/testing/selftests/mm/split_huge_page_test.c
index c01d227d7fd6d..295a6769d670b 100644
--- a/tools/testing/selftests/mm/split_huge_page_test.c
+++ b/tools/testing/selftests/mm/split_huge_page_test.c
@@ -658,7 +658,7 @@ int main(int argc, char **argv)
 
 	pagesize = getpagesize();
 	pageshift = ffs(pagesize) - 1;
-	pmd_pagesize = read_pmd_pagesize();
+	pmd_pagesize = pmd_psize();
 	if (!pmd_pagesize)
 		ksft_exit_fail_msg("Reading PMD pagesize failed\n");
 
diff --git a/tools/testing/selftests/mm/uffd-common.c b/tools/testing/selftests/mm/uffd-common.c
index 1fb967ef49854..0b8bbb55c3357 100644
--- a/tools/testing/selftests/mm/uffd-common.c
+++ b/tools/testing/selftests/mm/uffd-common.c
@@ -137,7 +137,7 @@ static void shmem_release_pages(uffd_global_test_opts_t *gopts, char *rel_area)
 static int shmem_allocate_area(uffd_global_test_opts_t *gopts, void **alloc_area, bool is_src)
 {
 	void *area_alias = NULL;
-	size_t bytes = gopts->nr_pages * gopts->page_size, hpage_size = read_pmd_pagesize();
+	size_t bytes = gopts->nr_pages * gopts->page_size, hpage_size = pmd_psize();
 	unsigned long offset = is_src ? 0 : bytes;
 	char *p = NULL, *p_alias = NULL;
 	int mem_fd = uffd_mem_fd_create(bytes * 2, false);
@@ -194,10 +194,10 @@ static void shmem_alias_mapping(uffd_global_test_opts_t *gopts, __u64 *start,
 
 static void shmem_check_pmd_mapping(uffd_global_test_opts_t *gopts, void *p, int expect_nr_hpages)
 {
-	size_t len = expect_nr_hpages * read_pmd_pagesize();
+	size_t len = expect_nr_hpages * pmd_psize();
 
 	if (!check_huge_shmem(gopts->area_dst_alias, len, expect_nr_hpages,
-			      read_pmd_pagesize()))
+			      pmd_psize()))
 		err("Did not find expected %d number of hugepages",
 		    expect_nr_hpages);
 }
diff --git a/tools/testing/selftests/mm/uffd-unit-tests.c b/tools/testing/selftests/mm/uffd-unit-tests.c
index ef9b3956bdcfd..05477466af1b2 100644
--- a/tools/testing/selftests/mm/uffd-unit-tests.c
+++ b/tools/testing/selftests/mm/uffd-unit-tests.c
@@ -588,7 +588,7 @@ static void uffd_minor_test_common(uffd_global_test_opts_t *gopts, bool test_col
 		uffd_test_ops->check_pmd_mapping(gopts,
 						 gopts->area_dst,
 						 gopts->nr_pages * gopts->page_size /
-						 read_pmd_pagesize());
+						 pmd_psize());
 		/*
 		 * This won't cause uffd-fault - it purely just makes sure there
 		 * was no corruption.
@@ -1914,7 +1914,7 @@ static void uffd_move_handle_fault(uffd_global_test_opts_t *gopts, struct uffd_m
 static void uffd_move_pmd_handle_fault(uffd_global_test_opts_t *gopts, struct uffd_msg *msg,
 				       struct uffd_args *args)
 {
-	uffd_move_handle_fault_common(gopts, msg, args, read_pmd_pagesize());
+	uffd_move_handle_fault_common(gopts, msg, args, pmd_psize());
 }
 
 static void
@@ -2025,7 +2025,7 @@ static void uffd_move_pmd_test(uffd_global_test_opts_t *gopts, uffd_test_args_t
 {
 	if (madvise(gopts->area_dst, gopts->nr_pages * gopts->page_size, MADV_HUGEPAGE))
 		err("madvise(MADV_HUGEPAGE) failure");
-	uffd_move_test_common(gopts, targs, read_pmd_pagesize(),
+	uffd_move_test_common(gopts, targs, pmd_psize(),
 			      uffd_move_pmd_handle_fault);
 }
 
@@ -2033,7 +2033,7 @@ static void uffd_move_pmd_split_test(uffd_global_test_opts_t *gopts, uffd_test_a
 {
 	if (madvise(gopts->area_dst, gopts->nr_pages * gopts->page_size, MADV_NOHUGEPAGE))
 		err("madvise(MADV_NOHUGEPAGE) failure");
-	uffd_move_test_common(gopts, targs, read_pmd_pagesize(),
+	uffd_move_test_common(gopts, targs, pmd_psize(),
 			      uffd_move_pmd_handle_fault);
 }
 
diff --git a/tools/testing/selftests/mm/uffd-wp-mremap.c b/tools/testing/selftests/mm/uffd-wp-mremap.c
index 572c2516e874d..f46edd3ee6d81 100644
--- a/tools/testing/selftests/mm/uffd-wp-mremap.c
+++ b/tools/testing/selftests/mm/uffd-wp-mremap.c
@@ -38,7 +38,7 @@ static int detect_thp_sizes(size_t sizes[], int max)
 	int i;
 
 	/* thp not supported at all. */
-	if (!read_pmd_pagesize())
+	if (!pmd_psize())
 		return 0;
 
 	orders = thp_supported_orders();
diff --git a/tools/testing/selftests/mm/vm_util.c b/tools/testing/selftests/mm/vm_util.c
index 4821a35630363..e712a980851c8 100644
--- a/tools/testing/selftests/mm/vm_util.c
+++ b/tools/testing/selftests/mm/vm_util.c
@@ -155,7 +155,7 @@ bool check_for_pattern(FILE *fp, const char *pattern, char *buf, size_t len)
 	return false;
 }
 
-uint64_t read_pmd_pagesize(void)
+uint64_t pmd_psize(void)
 {
 	int fd;
 	char buf[20];
@@ -412,7 +412,7 @@ static bool check_large_folios(void *addr, size_t len, int nr_hpages,
 
 bool check_huge_anon(void *addr, size_t len, int nr_hpages, uint64_t hpage_size)
 {
-	uint64_t pmd_pagesize = read_pmd_pagesize();
+	uint64_t pmd_pagesize = pmd_psize();
 
 	if (!pmd_pagesize)
 		ksft_exit_fail_msg("reading PMD pagesize failed\n");
@@ -425,7 +425,7 @@ bool check_huge_anon(void *addr, size_t len, int nr_hpages, uint64_t hpage_size)
 
 bool check_huge_file(void *addr, size_t len, int nr_hpages, uint64_t hpage_size)
 {
-	uint64_t pmd_pagesize = read_pmd_pagesize();
+	uint64_t pmd_pagesize = pmd_psize();
 
 	if (!pmd_pagesize)
 		ksft_exit_fail_msg("reading PMD pagesize failed\n");
@@ -438,7 +438,7 @@ bool check_huge_file(void *addr, size_t len, int nr_hpages, uint64_t hpage_size)
 
 bool check_huge_shmem(void *addr, size_t len, int nr_hpages, uint64_t hpage_size)
 {
-	uint64_t pmd_pagesize = read_pmd_pagesize();
+	uint64_t pmd_pagesize = pmd_psize();
 
 	if (!pmd_pagesize)
 		ksft_exit_fail_msg("reading PMD pagesize failed\n");
diff --git a/tools/testing/selftests/mm/vm_util.h b/tools/testing/selftests/mm/vm_util.h
index 9a49af88702e4..a40e40c820ef7 100644
--- a/tools/testing/selftests/mm/vm_util.h
+++ b/tools/testing/selftests/mm/vm_util.h
@@ -88,7 +88,7 @@ bool pagemap_is_populated(int fd, char *start);
 unsigned long pagemap_get_pfn(int fd, char *start);
 void clear_softdirty(void);
 bool check_for_pattern(FILE *fp, const char *pattern, char *buf, size_t len);
-uint64_t read_pmd_pagesize(void);
+uint64_t pmd_psize(void);
 unsigned long rss_anon(void);
 bool check_huge_anon(void *addr, size_t len, int nr_hpages, uint64_t hpage_size);
 bool check_huge_file(void *addr, size_t len, int nr_hpages, uint64_t hpage_size);

-- 
2.43.0

[PATCH v4 2/3] kselftest: mm: remove HPAGE_SIZE and HPAGE_SHIFT macro

[Yeoreum Yun]

HPAGE_SIZE and HPAGE_SHIFT macro is written based on the 4KB PAGE_SIZE.
When this macro is used in some test, test result would be strange in
the system where PAGE_SIZE is more then 4KB.

Here is the example with transhuge-stress test with 16KB PAGE_SIZE:

  transhuge-stress: allocate 61073 transhuge pages, using 122146 MiB virtual memory and 1908 MiB of ram
    3.292 s/loop, 0.054 ms/page,  37106.002 MiB/s	2566 succeed, 58507 failed, 2566 different pages
    0.591 s/loop, 0.010 ms/page, 206850.792 MiB/s	   0 succeed, 61073 failed,    0 different pages
    0.527 s/loop, 0.009 ms/page, 231895.107 MiB/s	   0 succeed, 61073 failed,    0 different pages
    0.527 s/loop, 0.009 ms/page, 231839.704 MiB/s	   0 succeed, 61073 failed,    0 different pages
    0.528 s/loop, 0.009 ms/page, 231544.782 MiB/s	   0 succeed, 61073 failed,    0 different pages
    0.528 s/loop, 0.009 ms/page, 231462.074 MiB/s	   0 succeed, 61073 failed,    0 different pages
    0.527 s/loop, 0.009 ms/page, 231770.300 MiB/s	   0 succeed, 61073 failed,    0 different pages
    ...
  ok 1 Completed

Remove the HPAGE_SIZE and HPAGE_SHIFT macro and introduce pmd_pshift()
helper to get the HPAGE_SHIFT properly. For HPAGE_SIZE, use pre-existing
helper, pmd_psize().

Also, run the KSM_MERGE_TIME_HUGE_PAGES test with a size of 512 MiB,
which is the least common multiple of the PMD sizes for 4 KiB, 16 KiB,
and 64 KiB base pages. Since allocate_transhuge() allocates mappings in
PMD-sized units, the test may fail with the previous size of 100 MiB,
which is not a multiple of the PMD size when the base page size is
16 KiB or 64 KiB.

After this patch, output of transhuge-stress:

  transhuge-stress: allocate 3817 transhuge pages, using 122146 MiB virtual memory and 119 MiB of ram
    2.558 s/loop, 0.670 ms/page,  47755.759 MiB/s	2585 succeed, 1232 failed, 2585 different pages
    2.640 s/loop, 0.692 ms/page,  46268.432 MiB/s	2585 succeed, 1232 failed, 2585 different pages
    2.635 s/loop, 0.690 ms/page,  46360.298 MiB/s	2585 succeed, 1232 failed, 2585 different pages
    2.782 s/loop, 0.729 ms/page,  43899.795 MiB/s	2616 succeed, 1201 failed, 2616 different pages
    2.692 s/loop, 0.705 ms/page,  45380.876 MiB/s	2627 succeed, 1190 failed, 2627 different pages
    2.612 s/loop, 0.684 ms/page,  46765.812 MiB/s	2628 succeed, 1189 failed, 2628 different pages
    2.683 s/loop, 0.703 ms/page,  45520.990 MiB/s	2630 succeed, 1187 failed, 2630 different pages
    2.727 s/loop, 0.714 ms/page,  44789.321 MiB/s	2631 succeed, 1186 failed, 2631 different pages
    ...
  ok 1 Completed

Suggested-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Signed-off-by: Yeoreum Yun <yeoreum.yun@arm.com>
---
 tools/testing/selftests/mm/guard-regions.c    | 11 ++++++--
 tools/testing/selftests/mm/ksm_tests.c        | 16 ++++++-----
 tools/testing/selftests/mm/run_vmtests.sh     |  4 +--
 tools/testing/selftests/mm/transhuge-stress.c | 25 +++++++++++-------
 tools/testing/selftests/mm/vm_util.c          | 38 +++++++++++++++++++++++----
 tools/testing/selftests/mm/vm_util.h          |  9 +++----
 6 files changed, 72 insertions(+), 31 deletions(-)

diff --git a/tools/testing/selftests/mm/guard-regions.c b/tools/testing/selftests/mm/guard-regions.c
index b724d62d2b755..eee29ef88cb20 100644
--- a/tools/testing/selftests/mm/guard-regions.c
+++ b/tools/testing/selftests/mm/guard-regions.c
@@ -2195,14 +2195,21 @@ TEST_F(guard_regions, pagemap_scan)
 TEST_F(guard_regions, collapse)
 {
 	const unsigned long page_size = self->page_size;
-	const unsigned long size = 2 * HPAGE_SIZE;
-	const unsigned long num_pages = size / page_size;
+	const uint64_t hpage_size = pmd_psize();
+	unsigned long size;
+	unsigned long num_pages;
 	char *ptr;
 	int i;
 
 	if (!thp_available())
 		SKIP(return, "Transparent Hugepages not available\n");
 
+	if (!hpage_size)
+		ksft_exit_fail_msg("reading hpage_size failed\n");
+
+	size = 2 * hpage_size;
+	num_pages = size / page_size;
+
 	/* Need file to be correct size for tests for non-anon. */
 	if (variant->backing != ANON_BACKED)
 		ASSERT_EQ(ftruncate(self->fd, size), 0);
diff --git a/tools/testing/selftests/mm/ksm_tests.c b/tools/testing/selftests/mm/ksm_tests.c
index 5fd7792a0d479..617e31138af06 100644
--- a/tools/testing/selftests/mm/ksm_tests.c
+++ b/tools/testing/selftests/mm/ksm_tests.c
@@ -521,19 +521,23 @@ static int ksm_merge_hugepages_time(int merge_type, int mapping, int prot,
 	struct timespec start_time, end_time;
 	unsigned long scan_time_ns;
 	int pagemap_fd, n_normal_pages, n_huge_pages;
+	const uint64_t hpage_size = pmd_psize();
 
 	if (!thp_is_enabled()) {
 		ksft_print_msg("Transparent Hugepages not available\n");
 		return KSFT_SKIP;
 	}
 
+	if (!hpage_size)
+		ksft_exit_fail_msg("reading hpage_size failed\n");
+
 	map_size *= MB;
 	size_t len = map_size;
 
-	len -= len % HPAGE_SIZE;
-	map_ptr_orig = mmap(NULL, len + HPAGE_SIZE, PROT_READ | PROT_WRITE,
+	len -= len % hpage_size;
+	map_ptr_orig = mmap(NULL, len + hpage_size, PROT_READ | PROT_WRITE,
 			MAP_ANONYMOUS | MAP_NORESERVE | MAP_PRIVATE, -1, 0);
-	map_ptr = map_ptr_orig + HPAGE_SIZE - (uintptr_t)map_ptr_orig % HPAGE_SIZE;
+	map_ptr = map_ptr_orig + hpage_size - (uintptr_t)map_ptr_orig % hpage_size;
 
 	if (map_ptr_orig == MAP_FAILED)
 		err(2, "initial mmap");
@@ -547,7 +551,7 @@ static int ksm_merge_hugepages_time(int merge_type, int mapping, int prot,
 
 	n_normal_pages = 0;
 	n_huge_pages = 0;
-	for (void *p = map_ptr; p < map_ptr + len; p += HPAGE_SIZE) {
+	for (void *p = map_ptr; p < map_ptr + len; p += hpage_size) {
 		if (allocate_transhuge(p, pagemap_fd) < 0)
 			n_normal_pages++;
 		else
@@ -578,11 +582,11 @@ static int ksm_merge_hugepages_time(int merge_type, int mapping, int prot,
 	ksft_print_msg("Average speed:  %.3f MiB/s\n", (map_size / MB) /
 					       ((double)scan_time_ns / NSEC_PER_SEC));
 
-	munmap(map_ptr_orig, len + HPAGE_SIZE);
+	munmap(map_ptr_orig, len + hpage_size);
 	return KSFT_PASS;
 
 err_out:
-	munmap(map_ptr_orig, len + HPAGE_SIZE);
+	munmap(map_ptr_orig, len + hpage_size);
 	return KSFT_FAIL;
 }
 
diff --git a/tools/testing/selftests/mm/run_vmtests.sh b/tools/testing/selftests/mm/run_vmtests.sh
index 19755fb4edb94..345d1a79f07ef 100755
--- a/tools/testing/selftests/mm/run_vmtests.sh
+++ b/tools/testing/selftests/mm/run_vmtests.sh
@@ -378,8 +378,8 @@ fi
 CATEGORY="memfd_secret" run_test ./memfd_secret
 fi
 
-# KSM KSM_MERGE_TIME_HUGE_PAGES test with size of 100
-CATEGORY="ksm" run_test ./ksm_tests -H -s 100
+# KSM KSM_MERGE_TIME_HUGE_PAGES test with size of 512
+CATEGORY="ksm" run_test ./ksm_tests -H -s 512
 # KSM KSM_MERGE_TIME test with size of 100
 CATEGORY="ksm" run_test ./ksm_tests -P -s 100
 # KSM MADV_MERGEABLE test with 10 identical pages
diff --git a/tools/testing/selftests/mm/transhuge-stress.c b/tools/testing/selftests/mm/transhuge-stress.c
index 8eb0c5630e7e3..40ca224a61f49 100644
--- a/tools/testing/selftests/mm/transhuge-stress.c
+++ b/tools/testing/selftests/mm/transhuge-stress.c
@@ -35,12 +35,17 @@ int main(int argc, char **argv)
 	size_t map_len;
 	int pagemap_fd;
 	int duration = 0;
+	const uint64_t hpage_size = pmd_psize();
+	const uint64_t hpage_shift = pmd_pshift();
 
 	ksft_print_header();
 
 	if (!thp_is_enabled())
 		ksft_exit_skip("Transparent Hugepages not available\n");
 
+	if (!hpage_size || !hpage_shift)
+		ksft_exit_fail_msg("reading hpage_size failed\n");
+
 	ram = sysconf(_SC_PHYS_PAGES);
 	if (ram > SIZE_MAX / psize() / 4)
 		ram = SIZE_MAX / 4;
@@ -70,23 +75,23 @@ int main(int argc, char **argv)
 	}
 
 	warnx("allocate %zd transhuge pages, using %zd MiB virtual memory"
-	      " and %zd MiB of ram", len >> HPAGE_SHIFT, len >> 20,
-	      ram >> (20 + HPAGE_SHIFT - pshift() - 1));
+	      " and %zd MiB of ram", len >> hpage_shift, len >> 20,
+	      ram >> (20 + hpage_shift - pshift() - 1));
 
 	pagemap_fd = open("/proc/self/pagemap", O_RDONLY);
 	if (pagemap_fd < 0)
 		ksft_exit_fail_msg("open pagemap\n");
 
-	len -= len % HPAGE_SIZE;
-	ptr = mmap(NULL, len + HPAGE_SIZE, PROT_RW, mmap_flags, backing_fd, 0);
+	len -= len % hpage_size;
+	ptr = mmap(NULL, len + hpage_size, PROT_RW, mmap_flags, backing_fd, 0);
 	if (ptr == MAP_FAILED)
 		ksft_exit_fail_msg("initial mmap");
-	ptr += HPAGE_SIZE - (uintptr_t)ptr % HPAGE_SIZE;
+	ptr += hpage_size - (uintptr_t)ptr % hpage_size;
 
 	if (madvise(ptr, len, MADV_HUGEPAGE))
 		ksft_exit_fail_msg("MADV_HUGEPAGE");
 
-	map_len = ram >> (HPAGE_SHIFT - 1);
+	map_len = ram >> (hpage_shift - 1);
 	map = malloc(map_len);
 	if (!map)
 		ksft_exit_fail_msg("map malloc\n");
@@ -99,7 +104,7 @@ int main(int argc, char **argv)
 		memset(map, 0, map_len);
 
 		clock_gettime(CLOCK_MONOTONIC, &a);
-		for (p = ptr; p < ptr + len; p += HPAGE_SIZE) {
+		for (p = ptr; p < ptr + len; p += hpage_size) {
 			int64_t pfn;
 
 			pfn = allocate_transhuge(p, pagemap_fd);
@@ -107,7 +112,7 @@ int main(int argc, char **argv)
 			if (pfn < 0) {
 				nr_failed++;
 			} else {
-				size_t idx = pfn >> (HPAGE_SHIFT - pshift());
+				size_t idx = pfn >> (hpage_shift - pshift());
 
 				nr_succeed++;
 				if (idx >= map_len) {
@@ -123,7 +128,7 @@ int main(int argc, char **argv)
 			}
 
 			/* split transhuge page, keep last page */
-			if (madvise(p, HPAGE_SIZE - psize(), MADV_DONTNEED))
+			if (madvise(p, hpage_size - psize(), MADV_DONTNEED))
 				ksft_exit_fail_msg("MADV_DONTNEED");
 		}
 		clock_gettime(CLOCK_MONOTONIC, &b);
@@ -131,7 +136,7 @@ int main(int argc, char **argv)
 
 		ksft_print_msg("%.3f s/loop, %.3f ms/page, %10.3f MiB/s\t"
 			       "%4d succeed, %4d failed, %4d different pages\n",
-			       s, s * 1000 / (len >> HPAGE_SHIFT), len / s / (1 << 20),
+			       s, s * 1000 / (len >> hpage_shift), len / s / (1 << 20),
 			       nr_succeed, nr_failed, nr_pages);
 
 		if (duration > 0 && b.tv_sec - start.tv_sec >= duration) {
diff --git a/tools/testing/selftests/mm/vm_util.c b/tools/testing/selftests/mm/vm_util.c
index e712a980851c8..8f80e73dc22a5 100644
--- a/tools/testing/selftests/mm/vm_util.c
+++ b/tools/testing/selftests/mm/vm_util.c
@@ -21,6 +21,8 @@
 
 unsigned int __page_size;
 unsigned int __page_shift;
+uint64_t __pmd_psize = -1ull;
+uint64_t __pmd_pshift = -1ull;
 
 uint64_t pagemap_get_entry(int fd, char *start)
 {
@@ -161,19 +163,40 @@ uint64_t pmd_psize(void)
 	char buf[20];
 	ssize_t num_read;
 
+	if (__pmd_psize != -1ull)
+		return __pmd_psize;
+
 	fd = open(PMD_SIZE_FILE_PATH, O_RDONLY);
-	if (fd == -1)
+	if (fd == -1) {
+		__pmd_psize = 0;
 		return 0;
+	}
 
 	num_read = read(fd, buf, 19);
 	if (num_read < 1) {
+		__pmd_psize = 0;
 		close(fd);
 		return 0;
 	}
 	buf[num_read] = '\0';
 	close(fd);
 
-	return strtoul(buf, NULL, 10);
+	__pmd_psize = strtoul(buf, NULL, 10);
+
+	return __pmd_psize;
+}
+
+uint64_t pmd_pshift(void)
+{
+	if (__pmd_pshift != -1ull)
+		return __pmd_pshift;
+
+	if (__pmd_psize != -1ull)
+		__pmd_psize = pmd_psize();
+
+	__pmd_pshift = (__pmd_psize > 0) ? ffsl(__pmd_psize) - 1 : 0;
+
+	return __pmd_pshift;
 }
 
 unsigned long rss_anon(void)
@@ -452,14 +475,19 @@ bool check_huge_shmem(void *addr, size_t len, int nr_hpages, uint64_t hpage_size
 int64_t allocate_transhuge(void *ptr, int pagemap_fd)
 {
 	uint64_t ent[2];
+	const uint64_t hpage_size = pmd_psize();
+	const uint64_t hpage_shift = pmd_pshift();
+
+	if (!hpage_size || !hpage_shift)
+		return -1;
 
 	/* drop pmd */
-	if (mmap(ptr, HPAGE_SIZE, PROT_READ | PROT_WRITE,
+	if (mmap(ptr, hpage_size, PROT_READ | PROT_WRITE,
 		 MAP_FIXED | MAP_ANONYMOUS |
 		 MAP_NORESERVE | MAP_PRIVATE, -1, 0) != ptr)
 		ksft_exit_fail_msg("mmap transhuge\n");
 
-	if (madvise(ptr, HPAGE_SIZE, MADV_HUGEPAGE))
+	if (madvise(ptr, hpage_size, MADV_HUGEPAGE))
 		ksft_exit_fail_msg("MADV_HUGEPAGE\n");
 
 	/* allocate transparent huge page */
@@ -471,7 +499,7 @@ int64_t allocate_transhuge(void *ptr, int pagemap_fd)
 
 	if (PAGEMAP_PRESENT(ent[0]) && PAGEMAP_PRESENT(ent[1]) &&
 	    PAGEMAP_PFN(ent[0]) + 1 == PAGEMAP_PFN(ent[1]) &&
-	    !(PAGEMAP_PFN(ent[0]) & ((1 << (HPAGE_SHIFT - pshift())) - 1)))
+	    !(PAGEMAP_PFN(ent[0]) & ((1 << (hpage_shift - pshift())) - 1)))
 		return PAGEMAP_PFN(ent[0]);
 
 	return -1;
diff --git a/tools/testing/selftests/mm/vm_util.h b/tools/testing/selftests/mm/vm_util.h
index a40e40c820ef7..71af4804f8f24 100644
--- a/tools/testing/selftests/mm/vm_util.h
+++ b/tools/testing/selftests/mm/vm_util.h
@@ -31,6 +31,8 @@
 
 extern unsigned int __page_size;
 extern unsigned int __page_shift;
+extern uint64_t __pmd_psize;
+extern uint64_t __pmd_pshift;
 
 /*
  * Represents an open fd and PROCMAP_QUERY state for binary (via ioctl)
@@ -89,6 +91,7 @@ unsigned long pagemap_get_pfn(int fd, char *start);
 void clear_softdirty(void);
 bool check_for_pattern(FILE *fp, const char *pattern, char *buf, size_t len);
 uint64_t pmd_psize(void);
+uint64_t pmd_pshift(void);
 unsigned long rss_anon(void);
 bool check_huge_anon(void *addr, size_t len, int nr_hpages, uint64_t hpage_size);
 bool check_huge_file(void *addr, size_t len, int nr_hpages, uint64_t hpage_size);
@@ -157,12 +160,6 @@ int ksm_stop(void);
 int get_hardware_corrupted_size(unsigned long *val);
 int unpoison_memory(unsigned long pfn);
 
-/*
- * On ppc64 this will only work with radix 2M hugepage size
- */
-#define HPAGE_SHIFT 21
-#define HPAGE_SIZE (1 << HPAGE_SHIFT)
-
 #define PAGEMAP_PRESENT(ent)	(((ent) & (1ull << 63)) != 0)
 #define PAGEMAP_PFN(ent)	((ent) & ((1ull << 55) - 1))
 

-- 
2.43.0

[PATCH v4 3/3] kselftest: mm: introduce size_to_shift() helper

[Yeoreum Yun]

Introduce size_to_shift() for future users that need to
obtain shift of a huge-page which is other than pmd_psize().

Suggested-by: David Hildenbrand (Arm) <david@kernel.org>
Reviewed-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Signed-off-by: Yeoreum Yun <yeoreum.yun@arm.com>
---
 tools/testing/selftests/mm/vm_util.c |  2 +-
 tools/testing/selftests/mm/vm_util.h | 12 ++++++++++++
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/mm/vm_util.c b/tools/testing/selftests/mm/vm_util.c
index 8f80e73dc22a5..970671058397d 100644
--- a/tools/testing/selftests/mm/vm_util.c
+++ b/tools/testing/selftests/mm/vm_util.c
@@ -194,7 +194,7 @@ uint64_t pmd_pshift(void)
 	if (__pmd_psize != -1ull)
 		__pmd_psize = pmd_psize();
 
-	__pmd_pshift = (__pmd_psize > 0) ? ffsl(__pmd_psize) - 1 : 0;
+	__pmd_pshift = size_to_shift(__pmd_psize);
 
 	return __pmd_pshift;
 }
diff --git a/tools/testing/selftests/mm/vm_util.h b/tools/testing/selftests/mm/vm_util.h
index 71af4804f8f24..6e37c90f3c3a5 100644
--- a/tools/testing/selftests/mm/vm_util.h
+++ b/tools/testing/selftests/mm/vm_util.h
@@ -148,6 +148,18 @@ static inline int sz2ord(size_t size, size_t pagesize)
 	return __builtin_ctzll(size / pagesize);
 }
 
+static inline uint64_t size_to_shift(uint64_t size)
+{
+	/*
+	 * The function returns the corresponding shift only when the size
+	 * is a power of two; otherwise, it returns 0.
+	 */
+	if (!size || (size & (size - 1)))
+		return 0;
+
+	return ffsl(size) - 1;
+}
+
 void *sys_mremap(void *old_address, unsigned long old_size,
 		 unsigned long new_size, int flags, void *new_address);
 

-- 
2.43.0

Re: [PATCH v4 2/3] kselftest: mm: remove HPAGE_SIZE and HPAGE_SHIFT macro

[David Hildenbrand (Arm)]

On 9/21/26 12:36, Yeoreum Yun wrote:
> HPAGE_SIZE and HPAGE_SHIFT macro is written based on the 4KB PAGE_SIZE.
> When this macro is used in some test, test result would be strange in
> the system where PAGE_SIZE is more then 4KB.
> 
> Here is the example with transhuge-stress test with 16KB PAGE_SIZE:
> 
>   transhuge-stress: allocate 61073 transhuge pages, using 122146 MiB virtual memory and 1908 MiB of ram
>     3.292 s/loop, 0.054 ms/page,  37106.002 MiB/s	2566 succeed, 58507 failed, 2566 different pages
>     0.591 s/loop, 0.010 ms/page, 206850.792 MiB/s	   0 succeed, 61073 failed,    0 different pages
>     0.527 s/loop, 0.009 ms/page, 231895.107 MiB/s	   0 succeed, 61073 failed,    0 different pages
>     0.527 s/loop, 0.009 ms/page, 231839.704 MiB/s	   0 succeed, 61073 failed,    0 different pages
>     0.528 s/loop, 0.009 ms/page, 231544.782 MiB/s	   0 succeed, 61073 failed,    0 different pages
>     0.528 s/loop, 0.009 ms/page, 231462.074 MiB/s	   0 succeed, 61073 failed,    0 different pages
>     0.527 s/loop, 0.009 ms/page, 231770.300 MiB/s	   0 succeed, 61073 failed,    0 different pages
>     ...
>   ok 1 Completed
> 
> Remove the HPAGE_SIZE and HPAGE_SHIFT macro and introduce pmd_pshift()
> helper to get the HPAGE_SHIFT properly. For HPAGE_SIZE, use pre-existing
> helper, pmd_psize().
> 
> Also, run the KSM_MERGE_TIME_HUGE_PAGES test with a size of 512 MiB,
> which is the least common multiple of the PMD sizes for 4 KiB, 16 KiB,
> and 64 KiB base pages. Since allocate_transhuge() allocates mappings in
> PMD-sized units, the test may fail with the previous size of 100 MiB,
> which is not a multiple of the PMD size when the base page size is
> 16 KiB or 64 KiB.
> 
> After this patch, output of transhuge-stress:
> 
>   transhuge-stress: allocate 3817 transhuge pages, using 122146 MiB virtual memory and 119 MiB of ram
>     2.558 s/loop, 0.670 ms/page,  47755.759 MiB/s	2585 succeed, 1232 failed, 2585 different pages
>     2.640 s/loop, 0.692 ms/page,  46268.432 MiB/s	2585 succeed, 1232 failed, 2585 different pages
>     2.635 s/loop, 0.690 ms/page,  46360.298 MiB/s	2585 succeed, 1232 failed, 2585 different pages
>     2.782 s/loop, 0.729 ms/page,  43899.795 MiB/s	2616 succeed, 1201 failed, 2616 different pages
>     2.692 s/loop, 0.705 ms/page,  45380.876 MiB/s	2627 succeed, 1190 failed, 2627 different pages
>     2.612 s/loop, 0.684 ms/page,  46765.812 MiB/s	2628 succeed, 1189 failed, 2628 different pages
>     2.683 s/loop, 0.703 ms/page,  45520.990 MiB/s	2630 succeed, 1187 failed, 2630 different pages
>     2.727 s/loop, 0.714 ms/page,  44789.321 MiB/s	2631 succeed, 1186 failed, 2631 different pages
>     ...
>   ok 1 Completed
> 
> Suggested-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
> Reviewed-by: Zi Yan <ziy@nvidia.com>
> Signed-off-by: Yeoreum Yun <yeoreum.yun@arm.com>
> ---

Acked-by: David Hildenbrand (Arm) <david@kernel.org>

-- 
Cheers,

David

Re: [PATCH v4 3/3] kselftest: mm: introduce size_to_shift() helper

[David Hildenbrand (Arm)]

On 9/21/26 12:36, Yeoreum Yun wrote:
> Introduce size_to_shift() for future users that need to
> obtain shift of a huge-page which is other than pmd_psize().
> 
> Suggested-by: David Hildenbrand (Arm) <david@kernel.org>
> Reviewed-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
> Signed-off-by: Yeoreum Yun <yeoreum.yun@arm.com>
> ---

Acked-by: David Hildenbrand (Arm) <david@kernel.org>

-- 
Cheers,

David

Re: [PATCH v4 3/3] kselftest: mm: introduce size_to_shift() helper

[Zi Yan]

On 21 Sep 2026, at 6:36, Yeoreum Yun wrote:

> Introduce size_to_shift() for future users that need to
> obtain shift of a huge-page which is other than pmd_psize().
>
> Suggested-by: David Hildenbrand (Arm) <david@kernel.org>
> Reviewed-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
> Signed-off-by: Yeoreum Yun <yeoreum.yun@arm.com>
> ---
>  tools/testing/selftests/mm/vm_util.c |  2 +-
>  tools/testing/selftests/mm/vm_util.h | 12 ++++++++++++
>  2 files changed, 13 insertions(+), 1 deletion(-)
>
LGTM.

Reviewed-by: Zi Yan <ziy@nvidia.com>

Best Regards,
Yan, Zi

Re: [PATCH v4 2/3] kselftest: mm: remove HPAGE_SIZE and HPAGE_SHIFT macro

[Lorenzo Stoakes (ARM)]

On Mon, Sep 21, 2026 at 11:36:39AM +0100, Yeoreum Yun wrote:
> HPAGE_SIZE and HPAGE_SHIFT macro is written based on the 4KB PAGE_SIZE.
> When this macro is used in some test, test result would be strange in
> the system where PAGE_SIZE is more then 4KB.
>
> Here is the example with transhuge-stress test with 16KB PAGE_SIZE:
>
>   transhuge-stress: allocate 61073 transhuge pages, using 122146 MiB virtual memory and 1908 MiB of ram
>     3.292 s/loop, 0.054 ms/page,  37106.002 MiB/s	2566 succeed, 58507 failed, 2566 different pages
>     0.591 s/loop, 0.010 ms/page, 206850.792 MiB/s	   0 succeed, 61073 failed,    0 different pages
>     0.527 s/loop, 0.009 ms/page, 231895.107 MiB/s	   0 succeed, 61073 failed,    0 different pages
>     0.527 s/loop, 0.009 ms/page, 231839.704 MiB/s	   0 succeed, 61073 failed,    0 different pages
>     0.528 s/loop, 0.009 ms/page, 231544.782 MiB/s	   0 succeed, 61073 failed,    0 different pages
>     0.528 s/loop, 0.009 ms/page, 231462.074 MiB/s	   0 succeed, 61073 failed,    0 different pages
>     0.527 s/loop, 0.009 ms/page, 231770.300 MiB/s	   0 succeed, 61073 failed,    0 different pages
>     ...
>   ok 1 Completed
>
> Remove the HPAGE_SIZE and HPAGE_SHIFT macro and introduce pmd_pshift()
> helper to get the HPAGE_SHIFT properly. For HPAGE_SIZE, use pre-existing
> helper, pmd_psize().
>
> Also, run the KSM_MERGE_TIME_HUGE_PAGES test with a size of 512 MiB,
> which is the least common multiple of the PMD sizes for 4 KiB, 16 KiB,
> and 64 KiB base pages. Since allocate_transhuge() allocates mappings in
> PMD-sized units, the test may fail with the previous size of 100 MiB,
> which is not a multiple of the PMD size when the base page size is
> 16 KiB or 64 KiB.
>
> After this patch, output of transhuge-stress:
>
>   transhuge-stress: allocate 3817 transhuge pages, using 122146 MiB virtual memory and 119 MiB of ram
>     2.558 s/loop, 0.670 ms/page,  47755.759 MiB/s	2585 succeed, 1232 failed, 2585 different pages
>     2.640 s/loop, 0.692 ms/page,  46268.432 MiB/s	2585 succeed, 1232 failed, 2585 different pages
>     2.635 s/loop, 0.690 ms/page,  46360.298 MiB/s	2585 succeed, 1232 failed, 2585 different pages
>     2.782 s/loop, 0.729 ms/page,  43899.795 MiB/s	2616 succeed, 1201 failed, 2616 different pages
>     2.692 s/loop, 0.705 ms/page,  45380.876 MiB/s	2627 succeed, 1190 failed, 2627 different pages
>     2.612 s/loop, 0.684 ms/page,  46765.812 MiB/s	2628 succeed, 1189 failed, 2628 different pages
>     2.683 s/loop, 0.703 ms/page,  45520.990 MiB/s	2630 succeed, 1187 failed, 2630 different pages
>     2.727 s/loop, 0.714 ms/page,  44789.321 MiB/s	2631 succeed, 1186 failed, 2631 different pages
>     ...
>   ok 1 Completed
>
> Suggested-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
> Reviewed-by: Zi Yan <ziy@nvidia.com>
> Signed-off-by: Yeoreum Yun <yeoreum.yun@arm.com>

Thanks for fixing this!

LGTM so:

Reviewed-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>

> ---
>  tools/testing/selftests/mm/guard-regions.c    | 11 ++++++--
>  tools/testing/selftests/mm/ksm_tests.c        | 16 ++++++-----
>  tools/testing/selftests/mm/run_vmtests.sh     |  4 +--
>  tools/testing/selftests/mm/transhuge-stress.c | 25 +++++++++++-------
>  tools/testing/selftests/mm/vm_util.c          | 38 +++++++++++++++++++++++----
>  tools/testing/selftests/mm/vm_util.h          |  9 +++----
>  6 files changed, 72 insertions(+), 31 deletions(-)
>
> diff --git a/tools/testing/selftests/mm/guard-regions.c b/tools/testing/selftests/mm/guard-regions.c
> index b724d62d2b755..eee29ef88cb20 100644
> --- a/tools/testing/selftests/mm/guard-regions.c
> +++ b/tools/testing/selftests/mm/guard-regions.c
> @@ -2195,14 +2195,21 @@ TEST_F(guard_regions, pagemap_scan)
>  TEST_F(guard_regions, collapse)
>  {
>  	const unsigned long page_size = self->page_size;
> -	const unsigned long size = 2 * HPAGE_SIZE;
> -	const unsigned long num_pages = size / page_size;
> +	const uint64_t hpage_size = pmd_psize();
> +	unsigned long size;
> +	unsigned long num_pages;
>  	char *ptr;
>  	int i;
>
>  	if (!thp_available())
>  		SKIP(return, "Transparent Hugepages not available\n");
>
> +	if (!hpage_size)
> +		ksft_exit_fail_msg("reading hpage_size failed\n");
> +
> +	size = 2 * hpage_size;
> +	num_pages = size / page_size;
> +
>  	/* Need file to be correct size for tests for non-anon. */
>  	if (variant->backing != ANON_BACKED)
>  		ASSERT_EQ(ftruncate(self->fd, size), 0);
> diff --git a/tools/testing/selftests/mm/ksm_tests.c b/tools/testing/selftests/mm/ksm_tests.c
> index 5fd7792a0d479..617e31138af06 100644
> --- a/tools/testing/selftests/mm/ksm_tests.c
> +++ b/tools/testing/selftests/mm/ksm_tests.c
> @@ -521,19 +521,23 @@ static int ksm_merge_hugepages_time(int merge_type, int mapping, int prot,
>  	struct timespec start_time, end_time;
>  	unsigned long scan_time_ns;
>  	int pagemap_fd, n_normal_pages, n_huge_pages;
> +	const uint64_t hpage_size = pmd_psize();
>
>  	if (!thp_is_enabled()) {
>  		ksft_print_msg("Transparent Hugepages not available\n");
>  		return KSFT_SKIP;
>  	}
>
> +	if (!hpage_size)
> +		ksft_exit_fail_msg("reading hpage_size failed\n");
> +
>  	map_size *= MB;
>  	size_t len = map_size;
>
> -	len -= len % HPAGE_SIZE;
> -	map_ptr_orig = mmap(NULL, len + HPAGE_SIZE, PROT_READ | PROT_WRITE,
> +	len -= len % hpage_size;
> +	map_ptr_orig = mmap(NULL, len + hpage_size, PROT_READ | PROT_WRITE,
>  			MAP_ANONYMOUS | MAP_NORESERVE | MAP_PRIVATE, -1, 0);
> -	map_ptr = map_ptr_orig + HPAGE_SIZE - (uintptr_t)map_ptr_orig % HPAGE_SIZE;
> +	map_ptr = map_ptr_orig + hpage_size - (uintptr_t)map_ptr_orig % hpage_size;
>
>  	if (map_ptr_orig == MAP_FAILED)
>  		err(2, "initial mmap");
> @@ -547,7 +551,7 @@ static int ksm_merge_hugepages_time(int merge_type, int mapping, int prot,
>
>  	n_normal_pages = 0;
>  	n_huge_pages = 0;
> -	for (void *p = map_ptr; p < map_ptr + len; p += HPAGE_SIZE) {
> +	for (void *p = map_ptr; p < map_ptr + len; p += hpage_size) {
>  		if (allocate_transhuge(p, pagemap_fd) < 0)
>  			n_normal_pages++;
>  		else
> @@ -578,11 +582,11 @@ static int ksm_merge_hugepages_time(int merge_type, int mapping, int prot,
>  	ksft_print_msg("Average speed:  %.3f MiB/s\n", (map_size / MB) /
>  					       ((double)scan_time_ns / NSEC_PER_SEC));
>
> -	munmap(map_ptr_orig, len + HPAGE_SIZE);
> +	munmap(map_ptr_orig, len + hpage_size);
>  	return KSFT_PASS;
>
>  err_out:
> -	munmap(map_ptr_orig, len + HPAGE_SIZE);
> +	munmap(map_ptr_orig, len + hpage_size);
>  	return KSFT_FAIL;
>  }
>
> diff --git a/tools/testing/selftests/mm/run_vmtests.sh b/tools/testing/selftests/mm/run_vmtests.sh
> index 19755fb4edb94..345d1a79f07ef 100755
> --- a/tools/testing/selftests/mm/run_vmtests.sh
> +++ b/tools/testing/selftests/mm/run_vmtests.sh
> @@ -378,8 +378,8 @@ fi
>  CATEGORY="memfd_secret" run_test ./memfd_secret
>  fi
>
> -# KSM KSM_MERGE_TIME_HUGE_PAGES test with size of 100
> -CATEGORY="ksm" run_test ./ksm_tests -H -s 100
> +# KSM KSM_MERGE_TIME_HUGE_PAGES test with size of 512
> +CATEGORY="ksm" run_test ./ksm_tests -H -s 512
>  # KSM KSM_MERGE_TIME test with size of 100
>  CATEGORY="ksm" run_test ./ksm_tests -P -s 100
>  # KSM MADV_MERGEABLE test with 10 identical pages
> diff --git a/tools/testing/selftests/mm/transhuge-stress.c b/tools/testing/selftests/mm/transhuge-stress.c
> index 8eb0c5630e7e3..40ca224a61f49 100644
> --- a/tools/testing/selftests/mm/transhuge-stress.c
> +++ b/tools/testing/selftests/mm/transhuge-stress.c
> @@ -35,12 +35,17 @@ int main(int argc, char **argv)
>  	size_t map_len;
>  	int pagemap_fd;
>  	int duration = 0;
> +	const uint64_t hpage_size = pmd_psize();
> +	const uint64_t hpage_shift = pmd_pshift();
>
>  	ksft_print_header();
>
>  	if (!thp_is_enabled())
>  		ksft_exit_skip("Transparent Hugepages not available\n");
>
> +	if (!hpage_size || !hpage_shift)
> +		ksft_exit_fail_msg("reading hpage_size failed\n");
> +
>  	ram = sysconf(_SC_PHYS_PAGES);
>  	if (ram > SIZE_MAX / psize() / 4)
>  		ram = SIZE_MAX / 4;
> @@ -70,23 +75,23 @@ int main(int argc, char **argv)
>  	}
>
>  	warnx("allocate %zd transhuge pages, using %zd MiB virtual memory"
> -	      " and %zd MiB of ram", len >> HPAGE_SHIFT, len >> 20,
> -	      ram >> (20 + HPAGE_SHIFT - pshift() - 1));
> +	      " and %zd MiB of ram", len >> hpage_shift, len >> 20,
> +	      ram >> (20 + hpage_shift - pshift() - 1));
>
>  	pagemap_fd = open("/proc/self/pagemap", O_RDONLY);
>  	if (pagemap_fd < 0)
>  		ksft_exit_fail_msg("open pagemap\n");
>
> -	len -= len % HPAGE_SIZE;
> -	ptr = mmap(NULL, len + HPAGE_SIZE, PROT_RW, mmap_flags, backing_fd, 0);
> +	len -= len % hpage_size;
> +	ptr = mmap(NULL, len + hpage_size, PROT_RW, mmap_flags, backing_fd, 0);
>  	if (ptr == MAP_FAILED)
>  		ksft_exit_fail_msg("initial mmap");
> -	ptr += HPAGE_SIZE - (uintptr_t)ptr % HPAGE_SIZE;
> +	ptr += hpage_size - (uintptr_t)ptr % hpage_size;
>
>  	if (madvise(ptr, len, MADV_HUGEPAGE))
>  		ksft_exit_fail_msg("MADV_HUGEPAGE");
>
> -	map_len = ram >> (HPAGE_SHIFT - 1);
> +	map_len = ram >> (hpage_shift - 1);
>  	map = malloc(map_len);
>  	if (!map)
>  		ksft_exit_fail_msg("map malloc\n");
> @@ -99,7 +104,7 @@ int main(int argc, char **argv)
>  		memset(map, 0, map_len);
>
>  		clock_gettime(CLOCK_MONOTONIC, &a);
> -		for (p = ptr; p < ptr + len; p += HPAGE_SIZE) {
> +		for (p = ptr; p < ptr + len; p += hpage_size) {
>  			int64_t pfn;
>
>  			pfn = allocate_transhuge(p, pagemap_fd);
> @@ -107,7 +112,7 @@ int main(int argc, char **argv)
>  			if (pfn < 0) {
>  				nr_failed++;
>  			} else {
> -				size_t idx = pfn >> (HPAGE_SHIFT - pshift());
> +				size_t idx = pfn >> (hpage_shift - pshift());
>
>  				nr_succeed++;
>  				if (idx >= map_len) {
> @@ -123,7 +128,7 @@ int main(int argc, char **argv)
>  			}
>
>  			/* split transhuge page, keep last page */
> -			if (madvise(p, HPAGE_SIZE - psize(), MADV_DONTNEED))
> +			if (madvise(p, hpage_size - psize(), MADV_DONTNEED))
>  				ksft_exit_fail_msg("MADV_DONTNEED");
>  		}
>  		clock_gettime(CLOCK_MONOTONIC, &b);
> @@ -131,7 +136,7 @@ int main(int argc, char **argv)
>
>  		ksft_print_msg("%.3f s/loop, %.3f ms/page, %10.3f MiB/s\t"
>  			       "%4d succeed, %4d failed, %4d different pages\n",
> -			       s, s * 1000 / (len >> HPAGE_SHIFT), len / s / (1 << 20),
> +			       s, s * 1000 / (len >> hpage_shift), len / s / (1 << 20),
>  			       nr_succeed, nr_failed, nr_pages);
>
>  		if (duration > 0 && b.tv_sec - start.tv_sec >= duration) {
> diff --git a/tools/testing/selftests/mm/vm_util.c b/tools/testing/selftests/mm/vm_util.c
> index e712a980851c8..8f80e73dc22a5 100644
> --- a/tools/testing/selftests/mm/vm_util.c
> +++ b/tools/testing/selftests/mm/vm_util.c
> @@ -21,6 +21,8 @@
>
>  unsigned int __page_size;
>  unsigned int __page_shift;
> +uint64_t __pmd_psize = -1ull;
> +uint64_t __pmd_pshift = -1ull;
>
>  uint64_t pagemap_get_entry(int fd, char *start)
>  {
> @@ -161,19 +163,40 @@ uint64_t pmd_psize(void)
>  	char buf[20];
>  	ssize_t num_read;
>
> +	if (__pmd_psize != -1ull)
> +		return __pmd_psize;
> +
>  	fd = open(PMD_SIZE_FILE_PATH, O_RDONLY);
> -	if (fd == -1)
> +	if (fd == -1) {
> +		__pmd_psize = 0;
>  		return 0;
> +	}
>
>  	num_read = read(fd, buf, 19);
>  	if (num_read < 1) {
> +		__pmd_psize = 0;
>  		close(fd);
>  		return 0;
>  	}
>  	buf[num_read] = '\0';
>  	close(fd);
>
> -	return strtoul(buf, NULL, 10);
> +	__pmd_psize = strtoul(buf, NULL, 10);
> +
> +	return __pmd_psize;
> +}
> +
> +uint64_t pmd_pshift(void)
> +{
> +	if (__pmd_pshift != -1ull)
> +		return __pmd_pshift;
> +
> +	if (__pmd_psize != -1ull)
> +		__pmd_psize = pmd_psize();
> +
> +	__pmd_pshift = (__pmd_psize > 0) ? ffsl(__pmd_psize) - 1 : 0;
> +
> +	return __pmd_pshift;
>  }
>
>  unsigned long rss_anon(void)
> @@ -452,14 +475,19 @@ bool check_huge_shmem(void *addr, size_t len, int nr_hpages, uint64_t hpage_size
>  int64_t allocate_transhuge(void *ptr, int pagemap_fd)
>  {
>  	uint64_t ent[2];
> +	const uint64_t hpage_size = pmd_psize();
> +	const uint64_t hpage_shift = pmd_pshift();
> +
> +	if (!hpage_size || !hpage_shift)
> +		return -1;
>
>  	/* drop pmd */
> -	if (mmap(ptr, HPAGE_SIZE, PROT_READ | PROT_WRITE,
> +	if (mmap(ptr, hpage_size, PROT_READ | PROT_WRITE,
>  		 MAP_FIXED | MAP_ANONYMOUS |
>  		 MAP_NORESERVE | MAP_PRIVATE, -1, 0) != ptr)
>  		ksft_exit_fail_msg("mmap transhuge\n");
>
> -	if (madvise(ptr, HPAGE_SIZE, MADV_HUGEPAGE))
> +	if (madvise(ptr, hpage_size, MADV_HUGEPAGE))
>  		ksft_exit_fail_msg("MADV_HUGEPAGE\n");
>
>  	/* allocate transparent huge page */
> @@ -471,7 +499,7 @@ int64_t allocate_transhuge(void *ptr, int pagemap_fd)
>
>  	if (PAGEMAP_PRESENT(ent[0]) && PAGEMAP_PRESENT(ent[1]) &&
>  	    PAGEMAP_PFN(ent[0]) + 1 == PAGEMAP_PFN(ent[1]) &&
> -	    !(PAGEMAP_PFN(ent[0]) & ((1 << (HPAGE_SHIFT - pshift())) - 1)))
> +	    !(PAGEMAP_PFN(ent[0]) & ((1 << (hpage_shift - pshift())) - 1)))
>  		return PAGEMAP_PFN(ent[0]);
>
>  	return -1;
> diff --git a/tools/testing/selftests/mm/vm_util.h b/tools/testing/selftests/mm/vm_util.h
> index a40e40c820ef7..71af4804f8f24 100644
> --- a/tools/testing/selftests/mm/vm_util.h
> +++ b/tools/testing/selftests/mm/vm_util.h
> @@ -31,6 +31,8 @@
>
>  extern unsigned int __page_size;
>  extern unsigned int __page_shift;
> +extern uint64_t __pmd_psize;
> +extern uint64_t __pmd_pshift;
>
>  /*
>   * Represents an open fd and PROCMAP_QUERY state for binary (via ioctl)
> @@ -89,6 +91,7 @@ unsigned long pagemap_get_pfn(int fd, char *start);
>  void clear_softdirty(void);
>  bool check_for_pattern(FILE *fp, const char *pattern, char *buf, size_t len);
>  uint64_t pmd_psize(void);
> +uint64_t pmd_pshift(void);
>  unsigned long rss_anon(void);
>  bool check_huge_anon(void *addr, size_t len, int nr_hpages, uint64_t hpage_size);
>  bool check_huge_file(void *addr, size_t len, int nr_hpages, uint64_t hpage_size);
> @@ -157,12 +160,6 @@ int ksm_stop(void);
>  int get_hardware_corrupted_size(unsigned long *val);
>  int unpoison_memory(unsigned long pfn);
>
> -/*
> - * On ppc64 this will only work with radix 2M hugepage size
> - */
> -#define HPAGE_SHIFT 21
> -#define HPAGE_SIZE (1 << HPAGE_SHIFT)
> -
>  #define PAGEMAP_PRESENT(ent)	(((ent) & (1ull << 63)) != 0)
>  #define PAGEMAP_PFN(ent)	((ent) & ((1ull << 55) - 1))
>
>
> --
> 2.43.0
>

--
Cheers, Lorenzo