[PATCH v3 0/3] kselftest: mm: remove HPAGE_SIZE and HPAGE_SHIFT macro

[PATCH v3 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
=============
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               | 52 ++++++++++++++++++----
 tools/testing/selftests/mm/vm_util.h               | 12 +++--
 20 files changed, 116 insertions(+), 66 deletions(-)
---
base-commit: 6b41451631cabf9ea3b384c2a099088e1598f963
change-id: 20260909-fix_hpage_macro-da069ae04502

Best regards,
-- 
Sincerely,
Yeoreum Yun

[PATCH v3 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>
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 8aa5249d9bef..e42edeccfd7a 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 1960635a953e..a956e5c74c65 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 e2642eca0d02..ad14372b75d9 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 f82673f5f6b4..76c1fbcc5260 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 f19d53c69576..4280d2c87b22 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 68dd447a5454..49ef643a6e63 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 d9a4fb782ecf..d0e34dd5850b 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 82c6e96ea6eb..d0290c4567bd 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 3fffd5f7e6fb..7e32bad8ab2a 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 5f278913c4d7..670fcad083b5 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 c01d227d7fd6..295a6769d670 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 1fb967ef4985..0b8bbb55c335 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 6f2360f9b75d..dcb1755c35fb 100644
--- a/tools/testing/selftests/mm/uffd-unit-tests.c
+++ b/tools/testing/selftests/mm/uffd-unit-tests.c
@@ -646,7 +646,7 @@ 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.
@@ -1975,7 +1975,7 @@ 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
@@ -2086,7 +2086,7 @@ 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);
 }
 
@@ -2094,7 +2094,7 @@ 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 572c2516e874..f46edd3ee6d8 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 4821a3563036..e712a980851c 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 9a49af88702e..a40e40c820ef 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 v3 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>
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          | 36 ++++++++++++++++++++++++---
 tools/testing/selftests/mm/vm_util.h          |  9 +++----
 6 files changed, 71 insertions(+), 30 deletions(-)

diff --git a/tools/testing/selftests/mm/guard-regions.c b/tools/testing/selftests/mm/guard-regions.c
index b724d62d2b75..eee29ef88cb2 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 5fd7792a0d47..617e31138af0 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 0935dbef4884..d7beedd5e178 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 8eb0c5630e7e..40ca224a61f4 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 e712a980851c..fd1432dc6152 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;
+uint64_t __pmd_pshift;
 
 uint64_t pagemap_get_entry(int fd, char *start)
 {
@@ -161,6 +163,9 @@ uint64_t pmd_psize(void)
 	char buf[20];
 	ssize_t num_read;
 
+	if (__pmd_psize)
+		return __pmd_psize;
+
 	fd = open(PMD_SIZE_FILE_PATH, O_RDONLY);
 	if (fd == -1)
 		return 0;
@@ -173,7 +178,25 @@ uint64_t pmd_psize(void)
 	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)
+		return __pmd_pshift;
+
+	if (!__pmd_psize)
+		__pmd_psize = pmd_psize();
+
+	if (!__pmd_psize)
+		return 0;
+
+	__pmd_pshift = ffsl(__pmd_psize) - 1;
+
+	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 a40e40c820ef..71af4804f8f2 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 v3 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>
Signed-off-by: Yeoreum Yun <yeoreum.yun@arm.com>
---
 tools/testing/selftests/mm/vm_util.c | 10 +++++++++-
 tools/testing/selftests/mm/vm_util.h |  1 +
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/mm/vm_util.c b/tools/testing/selftests/mm/vm_util.c
index fd1432dc6152..1fef1266429f 100644
--- a/tools/testing/selftests/mm/vm_util.c
+++ b/tools/testing/selftests/mm/vm_util.c
@@ -157,6 +157,14 @@ bool check_for_pattern(FILE *fp, const char *pattern, char *buf, size_t len)
 	return false;
 }
 
+uint64_t size_to_shift(uint64_t size)
+{
+	if (__builtin_popcountll(size) != 1)
+		return 0;
+
+	return ffsl(size) - 1;
+}
+
 uint64_t pmd_psize(void)
 {
 	int fd;
@@ -194,7 +202,7 @@ uint64_t pmd_pshift(void)
 	if (!__pmd_psize)
 		return 0;
 
-	__pmd_pshift = ffsl(__pmd_psize) - 1;
+	__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 71af4804f8f2..0048e0e82770 100644
--- a/tools/testing/selftests/mm/vm_util.h
+++ b/tools/testing/selftests/mm/vm_util.h
@@ -90,6 +90,7 @@ 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 size_to_shift(uint64_t size);
 uint64_t pmd_psize(void);
 uint64_t pmd_pshift(void);
 unsigned long rss_anon(void);

-- 
2.43.0

Re: [PATCH v3 1/3] kselftest: mm: rename read_pmd_pagesize() to pmd_psize()

[David Hildenbrand (Arm)]

On 9/14/26 09:30, Yeoreum Yun wrote:
> For consistency with psize(), rename read_pmd_pagesize() to
> pmd_psize(). There is no functional change.
> 
> Suggested-by: David Hildenbrand (Arm) <david@kernel.org>
> Signed-off-by: Yeoreum Yun <yeoreum.yun@arm.com>
> ---

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

-- 
Cheers,

David

Re: [PATCH v3 3/3] kselftest: mm: introduce size_to_shift() helper

[David Hildenbrand (Arm)]

On 9/14/26 09:30, 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>
> Signed-off-by: Yeoreum Yun <yeoreum.yun@arm.com>
> ---
>  tools/testing/selftests/mm/vm_util.c | 10 +++++++++-
>  tools/testing/selftests/mm/vm_util.h |  1 +
>  2 files changed, 10 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/testing/selftests/mm/vm_util.c b/tools/testing/selftests/mm/vm_util.c
> index fd1432dc6152..1fef1266429f 100644
> --- a/tools/testing/selftests/mm/vm_util.c
> +++ b/tools/testing/selftests/mm/vm_util.c
> @@ -157,6 +157,14 @@ bool check_for_pattern(FILE *fp, const char *pattern, char *buf, size_t len)
>  	return false;
>  }
>  
> +uint64_t size_to_shift(uint64_t size)
> +{
> +	if (__builtin_popcountll(size) != 1)
> +		return 0;
> +
> +	return ffsl(size) - 1;
> +}

Could likely just be an inline helper?

-- 
Cheers,

David

Re: [PATCH v3 3/3] kselftest: mm: introduce size_to_shift() helper

[Yeoreum Yun]

On Mon, Sep 14, 2026 at 04:01:02PM +0200, David Hildenbrand (Arm) wrote:
> On 9/14/26 09:30, 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>
> > Signed-off-by: Yeoreum Yun <yeoreum.yun@arm.com>
> > ---
> >  tools/testing/selftests/mm/vm_util.c | 10 +++++++++-
> >  tools/testing/selftests/mm/vm_util.h |  1 +
> >  2 files changed, 10 insertions(+), 1 deletion(-)
> > 
> > diff --git a/tools/testing/selftests/mm/vm_util.c b/tools/testing/selftests/mm/vm_util.c
> > index fd1432dc6152..1fef1266429f 100644
> > --- a/tools/testing/selftests/mm/vm_util.c
> > +++ b/tools/testing/selftests/mm/vm_util.c
> > @@ -157,6 +157,14 @@ bool check_for_pattern(FILE *fp, const char *pattern, char *buf, size_t len)
> >  	return false;
> >  }
> >  
> > +uint64_t size_to_shift(uint64_t size)
> > +{
> > +	if (__builtin_popcountll(size) != 1)
> > +		return 0;
> > +
> > +	return ffsl(size) - 1;
> > +}
> 
> Could likely just be an inline helper?

Okay. If there is no comments on today, I'll post tomorrow with this.

-- 
Sincerely,
Yeoreum Yun

Re: [PATCH v3 2/3] kselftest: mm: remove HPAGE_SIZE and HPAGE_SHIFT macro

[David Hildenbrand (Arm)]

On 9/14/26 09:30, 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>
> Signed-off-by: Yeoreum Yun <yeoreum.yun@arm.com>
> ---

[...]

> index e712a980851c..fd1432dc6152 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;
> +uint64_t __pmd_pshift;
>  
>  uint64_t pagemap_get_entry(int fd, char *start)
>  {
> @@ -161,6 +163,9 @@ uint64_t pmd_psize(void)
>  	char buf[20];
>  	ssize_t num_read;
>  
> +	if (__pmd_psize)
> +		return __pmd_psize;

The only suboptmial thing about these functions is that we keep querying
repeatedly in case of failure.

If it failed once, it will fail always.

You could either add a new variable for "queried" or encode it in the variables like

uint64_t __pmd_psize = -1ull;
uint64_t __pmd_pshift = -1ull;

To then set them to 0 or the actual value after we queried.

-- 
Cheers,

David

Re: [PATCH v3 3/3] kselftest: mm: introduce size_to_shift() helper

[David Hildenbrand (Arm)]

On 9/14/26 16:06, Yeoreum Yun wrote:
> On Mon, Sep 14, 2026 at 04:01:02PM +0200, David Hildenbrand (Arm) wrote:
>> On 9/14/26 09:30, 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>
>>> Signed-off-by: Yeoreum Yun <yeoreum.yun@arm.com>
>>> ---
>>>  tools/testing/selftests/mm/vm_util.c | 10 +++++++++-
>>>  tools/testing/selftests/mm/vm_util.h |  1 +
>>>  2 files changed, 10 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/tools/testing/selftests/mm/vm_util.c b/tools/testing/selftests/mm/vm_util.c
>>> index fd1432dc6152..1fef1266429f 100644
>>> --- a/tools/testing/selftests/mm/vm_util.c
>>> +++ b/tools/testing/selftests/mm/vm_util.c
>>> @@ -157,6 +157,14 @@ bool check_for_pattern(FILE *fp, const char *pattern, char *buf, size_t len)
>>>  	return false;
>>>  }
>>>  
>>> +uint64_t size_to_shift(uint64_t size)
>>> +{
>>> +	if (__builtin_popcountll(size) != 1)
>>> +		return 0;
>>> +
>>> +	return ffsl(size) - 1;
>>> +}
>>
>> Could likely just be an inline helper?
> 
> Okay. If there is no comments on today, I'll post tomorrow with this.
> 

No need to rush, leave some more days for people to catch up.

-- 
Cheers,

David

Re: [PATCH v3 2/3] kselftest: mm: remove HPAGE_SIZE and HPAGE_SHIFT macro

[Yeoreum Yun]

On Mon, Sep 14, 2026 at 04:08:03PM +0200, David Hildenbrand (Arm) wrote:
> On 9/14/26 09:30, 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>
> > Signed-off-by: Yeoreum Yun <yeoreum.yun@arm.com>
> > ---
> 
> [...]
> 
> > index e712a980851c..fd1432dc6152 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;
> > +uint64_t __pmd_pshift;
> >  
> >  uint64_t pagemap_get_entry(int fd, char *start)
> >  {
> > @@ -161,6 +163,9 @@ uint64_t pmd_psize(void)
> >  	char buf[20];
> >  	ssize_t num_read;
> >  
> > +	if (__pmd_psize)
> > +		return __pmd_psize;
> 
> The only suboptmial thing about these functions is that we keep querying
> repeatedly in case of failure.
> 
> If it failed once, it will fail always.
> 
> You could either add a new variable for "queried" or encode it in the variables like
> 
> uint64_t __pmd_psize = -1ull;
> uint64_t __pmd_pshift = -1ull;
> 
> To then set them to 0 or the actual value after we queried.

Okay. I'll respin it with above.

Thanks.


-- 
Sincerely,
Yeoreum Yun

Re: [PATCH v3 1/3] kselftest: mm: rename read_pmd_pagesize() to pmd_psize()

[Zi Yan]

On Mon Sep 14, 2026 at 3:30 AM EDT, Yeoreum Yun wrote:
> For consistency with psize(), rename read_pmd_pagesize() to
> pmd_psize(). There is no functional change.
>
> Suggested-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(-)
>

LGTM.

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


-- 
Best Regards,
Yan, Zi

Re: [PATCH v3 2/3] kselftest: mm: remove HPAGE_SIZE and HPAGE_SHIFT macro

[Zi Yan]

On Mon Sep 14, 2026 at 3:30 AM EDT, 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>
> 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          | 36 ++++++++++++++++++++++++---
>  tools/testing/selftests/mm/vm_util.h          |  9 +++----
>  6 files changed, 71 insertions(+), 30 deletions(-)
>
> diff --git a/tools/testing/selftests/mm/guard-regions.c b/tools/testing/selftests/mm/guard-regions.c
> index b724d62d2b75..eee29ef88cb2 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();

Is it better to use pmd_page_size/pmd_page_shift instead of
hpage_size/hpage_shift for clarification? Maybe in a follow-up patch if
you think it is reasonable.

Otherwise, with David's concern addressed, feel free to add

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

-- 
Best Regards,
Yan, Zi

Re: [PATCH v3 1/3] kselftest: mm: rename read_pmd_pagesize() to pmd_psize()

[Lorenzo Stoakes (ARM)]

On Mon, Sep 14, 2026 at 08:30:46AM +0100, Yeoreum Yun wrote:
> For consistency with psize(), rename read_pmd_pagesize() to
> pmd_psize(). There is no functional change.
>
> Suggested-by: David Hildenbrand (Arm) <david@kernel.org>
> Signed-off-by: Yeoreum Yun <yeoreum.yun@arm.com>

LGTM so:

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

> ---
>  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 8aa5249d9bef..e42edeccfd7a 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 1960635a953e..a956e5c74c65 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 e2642eca0d02..ad14372b75d9 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 f82673f5f6b4..76c1fbcc5260 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 f19d53c69576..4280d2c87b22 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 68dd447a5454..49ef643a6e63 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 d9a4fb782ecf..d0e34dd5850b 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 82c6e96ea6eb..d0290c4567bd 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 3fffd5f7e6fb..7e32bad8ab2a 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 5f278913c4d7..670fcad083b5 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 c01d227d7fd6..295a6769d670 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 1fb967ef4985..0b8bbb55c335 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 6f2360f9b75d..dcb1755c35fb 100644
> --- a/tools/testing/selftests/mm/uffd-unit-tests.c
> +++ b/tools/testing/selftests/mm/uffd-unit-tests.c
> @@ -646,7 +646,7 @@ 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.
> @@ -1975,7 +1975,7 @@ 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
> @@ -2086,7 +2086,7 @@ 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);
>  }
>
> @@ -2094,7 +2094,7 @@ 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 572c2516e874..f46edd3ee6d8 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 4821a3563036..e712a980851c 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 9a49af88702e..a40e40c820ef 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
>

--
Cheers, Lorenzo

Re: [PATCH v3 3/3] kselftest: mm: introduce size_to_shift() helper

[Lorenzo Stoakes (ARM)]

On Mon, Sep 14, 2026 at 04:08:30PM +0200, David Hildenbrand (Arm) wrote:
> On 9/14/26 16:06, Yeoreum Yun wrote:
> > On Mon, Sep 14, 2026 at 04:01:02PM +0200, David Hildenbrand (Arm) wrote:
> >> On 9/14/26 09:30, 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>
> >>> Signed-off-by: Yeoreum Yun <yeoreum.yun@arm.com>
> >>> ---
> >>>  tools/testing/selftests/mm/vm_util.c | 10 +++++++++-
> >>>  tools/testing/selftests/mm/vm_util.h |  1 +
> >>>  2 files changed, 10 insertions(+), 1 deletion(-)
> >>>
> >>> diff --git a/tools/testing/selftests/mm/vm_util.c b/tools/testing/selftests/mm/vm_util.c
> >>> index fd1432dc6152..1fef1266429f 100644
> >>> --- a/tools/testing/selftests/mm/vm_util.c
> >>> +++ b/tools/testing/selftests/mm/vm_util.c
> >>> @@ -157,6 +157,14 @@ bool check_for_pattern(FILE *fp, const char *pattern, char *buf, size_t len)
> >>>  	return false;
> >>>  }
> >>>

Probably worth a comment here saying it's only for power-of-two sizes.

> >>> +uint64_t size_to_shift(uint64_t size)
> >>> +{
> >>> +	if (__builtin_popcountll(size) != 1)

I wonder if it wouldn't be better to just do the old trick of:

	if (!size || (size & (size - 1)))
		return 0;

?

> >>> +		return 0;
> >>> +
> >>> +	return ffsl(size) - 1;
> >>> +}
> >>
> >> Could likely just be an inline helper?
> >
> > Okay. If there is no comments on today, I'll post tomorrow with this.
> >
>
> No need to rush, leave some more days for people to catch up.

Agree with David seems better as an inline thing, the __builtin_xxx() should
be... built-in hopefully :P though I suggest something that wouldn't need that.

As long as strings.h is included in the header ofc for ffsl().

With the stuff above addressed, seems fine to me so:

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

>
> --
> Cheers,
>
> David

--
Cheers, Lorenzo

Re: [PATCH v3 2/3] kselftest: mm: remove HPAGE_SIZE and HPAGE_SHIFT macro

[Yeoreum Yun]

On Mon, Sep 14, 2026 at 10:26:59PM -0400, Zi Yan wrote:
> On Mon Sep 14, 2026 at 3:30 AM EDT, 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>
> > 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          | 36 ++++++++++++++++++++++++---
> >  tools/testing/selftests/mm/vm_util.h          |  9 +++----
> >  6 files changed, 71 insertions(+), 30 deletions(-)
> >
> > diff --git a/tools/testing/selftests/mm/guard-regions.c b/tools/testing/selftests/mm/guard-regions.c
> > index b724d62d2b75..eee29ef88cb2 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();
> 
> Is it better to use pmd_page_size/pmd_page_shift instead of
> hpage_size/hpage_shift for clarification? Maybe in a follow-up patch if
> you think it is reasonable.

He, I don’t have a strong opinion on this, but personally, I think
explicitly naming the huge-page size used by the tests pmd_page_size
makes it clearer. Still, if you think the suggested approach is better,
I’m happy to change it accordingly. ;)

> 
> Otherwise, with David's concern addressed, feel free to add
> 
> Reviewed-by: Zi Yan <ziy@nvidia.com>

Thanks!
> 
> -- 
> Best Regards,
> Yan, Zi
> 

-- 
Sincerely,
Yeoreum Yun

Re: [PATCH v3 3/3] kselftest: mm: introduce size_to_shift() helper

[Yeoreum Yun]

On Tue, Sep 15, 2026 at 10:01:58AM +0100, Lorenzo Stoakes (ARM) wrote:
> On Mon, Sep 14, 2026 at 04:08:30PM +0200, David Hildenbrand (Arm) wrote:
> > On 9/14/26 16:06, Yeoreum Yun wrote:
> > > On Mon, Sep 14, 2026 at 04:01:02PM +0200, David Hildenbrand (Arm) wrote:
> > >> On 9/14/26 09:30, 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>
> > >>> Signed-off-by: Yeoreum Yun <yeoreum.yun@arm.com>
> > >>> ---
> > >>>  tools/testing/selftests/mm/vm_util.c | 10 +++++++++-
> > >>>  tools/testing/selftests/mm/vm_util.h |  1 +
> > >>>  2 files changed, 10 insertions(+), 1 deletion(-)
> > >>>
> > >>> diff --git a/tools/testing/selftests/mm/vm_util.c b/tools/testing/selftests/mm/vm_util.c
> > >>> index fd1432dc6152..1fef1266429f 100644
> > >>> --- a/tools/testing/selftests/mm/vm_util.c
> > >>> +++ b/tools/testing/selftests/mm/vm_util.c
> > >>> @@ -157,6 +157,14 @@ bool check_for_pattern(FILE *fp, const char *pattern, char *buf, size_t len)
> > >>>  	return false;
> > >>>  }
> > >>>
> 
> Probably worth a comment here saying it's only for power-of-two sizes.

Okay.

> 
> > >>> +uint64_t size_to_shift(uint64_t size)
> > >>> +{
> > >>> +	if (__builtin_popcountll(size) != 1)
> 
> I wonder if it wouldn't be better to just do the old trick of:
> 
> 	if (!size || (size & (size - 1)))
> 		return 0;
> 
> ?
> 
> > >>> +		return 0;
> > >>> +
> > >>> +	return ffsl(size) - 1;
> > >>> +}
> > >>
> > >> Could likely just be an inline helper?
> > >
> > > Okay. If there is no comments on today, I'll post tomorrow with this.
> > >
> >
> > No need to rush, leave some more days for people to catch up.
> 
> Agree with David seems better as an inline thing, the __builtin_xxx() should
> be... built-in hopefully :P though I suggest something that wouldn't need that.

Whatever is, okay. I'll change with old-classic trick :)
> 
> As long as strings.h is included in the header ofc for ffsl().
> 
> With the stuff above addressed, seems fine to me so:
> 
> Reviewed-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>

Thanks!

> 
> >
> > --
> > Cheers,
> >
> > David
> 
> --
> Cheers, Lorenzo

-- 
Sincerely,
Yeoreum Yun