[PATCH] kselftest: mm: remove HPAGE_SIZE and HPAGE_SHIFT macro

[PATCH] 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 than 4KB.

Here is 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 hpshift()
helper to get the HPAGE_SHIFT properly. For HPAGE_SIZE, use pre-exist
helper, read_pmd_pagesize().

Also, do KSM_MERGE_TIME_HUGE_PAGES test with size of 512 MiB which
is the LCD pmd_size among 4KB, 16KB and 64KB page_size.

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    | 12 +++++--
 tools/testing/selftests/mm/ksm_tests.c        | 17 ++++++----
 tools/testing/selftests/mm/run_vmtests.sh     |  4 +--
 tools/testing/selftests/mm/transhuge-stress.c | 22 +++++++------
 tools/testing/selftests/mm/vm_util.c          | 32 ++++++++++++++++---
 tools/testing/selftests/mm/vm_util.h          |  9 ++----
 6 files changed, 66 insertions(+), 30 deletions(-)

diff --git a/tools/testing/selftests/mm/guard-regions.c b/tools/testing/selftests/mm/guard-regions.c
index 5c8ec3ca75d7..d370592b291f 100644
--- a/tools/testing/selftests/mm/guard-regions.c
+++ b/tools/testing/selftests/mm/guard-regions.c
@@ -2195,14 +2195,22 @@ 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;
+	uint64_t hpage_size;
+	unsigned long size;
+	unsigned long num_pages;
 	char *ptr;
 	int i;
 
 	if (!thp_available())
 		SKIP(return, "Transparent Hugepages not available\n");
 
+	hpage_size = read_pmd_pagesize();
+	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..278e77055007 100644
--- a/tools/testing/selftests/mm/ksm_tests.c
+++ b/tools/testing/selftests/mm/ksm_tests.c
@@ -521,6 +521,11 @@ 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;
+	uint64_t hpage_size = read_pmd_pagesize();
+
+	if (!hpage_size) {
+		ksft_exit_fail_msg("reading hpage_size failed\n");
+	}
 
 	if (!thp_is_enabled()) {
 		ksft_print_msg("Transparent Hugepages not available\n");
@@ -530,10 +535,10 @@ static int ksm_merge_hugepages_time(int merge_type, int mapping, int prot,
 	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 +552,7 @@ 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 +583,11 @@ 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 d09f9f6a384e..24aa1de27c25 100755
--- a/tools/testing/selftests/mm/run_vmtests.sh
+++ b/tools/testing/selftests/mm/run_vmtests.sh
@@ -360,8 +360,8 @@ 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..66ae94afaf8d 100644
--- a/tools/testing/selftests/mm/transhuge-stress.c
+++ b/tools/testing/selftests/mm/transhuge-stress.c
@@ -35,6 +35,8 @@ int main(int argc, char **argv)
 	size_t map_len;
 	int pagemap_fd;
 	int duration = 0;
+	uint64_t hpage_size = read_pmd_pagesize();
+	uint64_t hpage_shift = hpshift();
 
 	ksft_print_header();
 
@@ -70,23 +72,23 @@ 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 +101,7 @@ 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 +109,7 @@ 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 +125,7 @@ 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 +133,7 @@ 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 4821a3563036..4332f8fb2104 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 __hpage_size;
+uint64_t __hpage_shift;
 
 uint64_t pagemap_get_entry(int fd, char *start)
 {
@@ -161,6 +163,9 @@ uint64_t read_pmd_pagesize(void)
 	char buf[20];
 	ssize_t num_read;
 
+	if (__hpage_size)
+		return __hpage_size;
+
 	fd = open(PMD_SIZE_FILE_PATH, O_RDONLY);
 	if (fd == -1)
 		return 0;
@@ -173,7 +178,24 @@ uint64_t read_pmd_pagesize(void)
 	buf[num_read] = '\0';
 	close(fd);
 
-	return strtoul(buf, NULL, 10);
+	__hpage_size = strtoul(buf, NULL, 10);
+
+	return __hpage_size;
+}
+
+uint64_t hpshift(void)
+{
+	if (!__hpage_shift) {
+		if (!__hpage_size) {
+			__hpage_size = read_pmd_pagesize();
+			if (!__hpage_size)
+				ksft_exit_fail_msg("reading __hpage_size failed\n");
+		}
+
+		__hpage_shift = (ffsl(__hpage_size) - 1);
+	}
+
+	return __hpage_shift;
 }
 
 unsigned long rss_anon(void)
@@ -452,14 +474,16 @@ 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];
+	uint64_t hpage_size = read_pmd_pagesize();
+	uint64_t hpage_shift = hpshift();
 
 	/* 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 +495,7 @@ 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 9a49af88702e..20a6334605c7 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 __hpage_size;
+extern uint64_t __hpage_shift;
 
 /*
  * 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 read_pmd_pagesize(void);
+uint64_t hpshift(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))
 
-- 
LEVI:{C3F47F37-75D8-414A-A8BA-3980EC8A46D7}

Re: [PATCH] kselftest: mm: remove HPAGE_SIZE and HPAGE_SHIFT macro

[Andrew Morton]

On Wed,  2 Sep 2026 18:56:11 +0100 Yeoreum Yun <yeoreum.yun@arm.com> 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 than 4KB.
> 
> Here is example with transhuge-stress test with 16KB PAGE_SIZE:
> 
> ...
>
>   ok 1 Completed
> 
> Remove the HPAGE_SIZE and HPAGE_SHIFT macro. and introduce hpshift()
> helper to get the HPAGE_SHIFT properly. For HPAGE_SIZE, use pre-exist
> helper, read_pmd_pagesize().
> 
> Also, do KSM_MERGE_TIME_HUGE_PAGES test with size of 512 MiB which
> is the LCD pmd_size among 4KB, 16KB and 64KB page_size.
> 
> After this patch, output of transhuge-stress:
> 
> ...
>
>   ok 1 Completed

Thanks.  Sashiko made claims.  The first looks legit, although minor:
	https://sashiko.dev/#/patchset/20260902175611.1241118-1-yeoreum.yun@arm.com

Re: [PATCH] kselftest: mm: remove HPAGE_SIZE and HPAGE_SHIFT macro

[Yeoreum Yun]

On Wed, Sep 02, 2026 at 12:29:32PM -0700, Andrew Morton wrote:
> On Wed,  2 Sep 2026 18:56:11 +0100 Yeoreum Yun <yeoreum.yun@arm.com> 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 than 4KB.
> > 
> > Here is example with transhuge-stress test with 16KB PAGE_SIZE:
> > 
> > ...
> >
> >   ok 1 Completed
> > 
> > Remove the HPAGE_SIZE and HPAGE_SHIFT macro. and introduce hpshift()
> > helper to get the HPAGE_SHIFT properly. For HPAGE_SIZE, use pre-exist
> > helper, read_pmd_pagesize().
> > 
> > Also, do KSM_MERGE_TIME_HUGE_PAGES test with size of 512 MiB which
> > is the LCD pmd_size among 4KB, 16KB and 64KB page_size.
> > 
> > After this patch, output of transhuge-stress:
> > 
> > ...
> >
> >   ok 1 Completed
> 
> Thanks.  Sashiko made claims.  The first looks legit, although minor:
> 	https://sashiko.dev/#/patchset/20260902175611.1241118-1-yeoreum.yun@arm.com

Thanks! I'll fix!

-- 
Sincerely,
Yeoreum Yun

Re: [PATCH] kselftest: mm: remove HPAGE_SIZE and HPAGE_SHIFT macro

[Lorenzo Stoakes (ARM)]

On Wed, Sep 02, 2026 at 06:56:11PM +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 than 4KB.
>
> Here is 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 hpshift()
> helper to get the HPAGE_SHIFT properly. For HPAGE_SIZE, use pre-exist
> helper, read_pmd_pagesize().
>
> Also, do KSM_MERGE_TIME_HUGE_PAGES test with size of 512 MiB which
> is the LCD pmd_size among 4KB, 16KB and 64KB page_size.

Probably worth spelling out Least Common Denominator for those who might
mistaken this for a kind of display panel :P

I also wonder if it's worth pulling that out as a separate patch in a series for
better bisectability?

>
> 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>

Firstly THANK YOU for doing this :) hugely appreciated.

Also thank you again for the birthday cakes ;)

And apologies for the nitpicks :P

> ---
>  tools/testing/selftests/mm/guard-regions.c    | 12 +++++--
>  tools/testing/selftests/mm/ksm_tests.c        | 17 ++++++----
>  tools/testing/selftests/mm/run_vmtests.sh     |  4 +--
>  tools/testing/selftests/mm/transhuge-stress.c | 22 +++++++------
>  tools/testing/selftests/mm/vm_util.c          | 32 ++++++++++++++++---
>  tools/testing/selftests/mm/vm_util.h          |  9 ++----
>  6 files changed, 66 insertions(+), 30 deletions(-)
>
> diff --git a/tools/testing/selftests/mm/guard-regions.c b/tools/testing/selftests/mm/guard-regions.c
> index 5c8ec3ca75d7..d370592b291f 100644
> --- a/tools/testing/selftests/mm/guard-regions.c
> +++ b/tools/testing/selftests/mm/guard-regions.c
> @@ -2195,14 +2195,22 @@ 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;
> +	uint64_t hpage_size;
> +	unsigned long size;
> +	unsigned long num_pages;
>  	char *ptr;
>  	int i;
>
>  	if (!thp_available())
>  		SKIP(return, "Transparent Hugepages not available\n");
>
> +	hpage_size = read_pmd_pagesize();
> +	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..278e77055007 100644
> --- a/tools/testing/selftests/mm/ksm_tests.c
> +++ b/tools/testing/selftests/mm/ksm_tests.c
> @@ -521,6 +521,11 @@ 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;
> +	uint64_t hpage_size = read_pmd_pagesize();

NIT: can this be const?

> +
> +	if (!hpage_size) {
> +		ksft_exit_fail_msg("reading hpage_size failed\n");
> +	}

NIT: can drop the {}

>
>  	if (!thp_is_enabled()) {
>  		ksft_print_msg("Transparent Hugepages not available\n");
> @@ -530,10 +535,10 @@ static int ksm_merge_hugepages_time(int merge_type, int mapping, int prot,
>  	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 +552,7 @@ 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 +583,11 @@ 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 d09f9f6a384e..24aa1de27c25 100755
> --- a/tools/testing/selftests/mm/run_vmtests.sh
> +++ b/tools/testing/selftests/mm/run_vmtests.sh
> @@ -360,8 +360,8 @@ 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

See above re: splitting out.

>  # 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..66ae94afaf8d 100644
> --- a/tools/testing/selftests/mm/transhuge-stress.c
> +++ b/tools/testing/selftests/mm/transhuge-stress.c
> @@ -35,6 +35,8 @@ int main(int argc, char **argv)
>  	size_t map_len;
>  	int pagemap_fd;
>  	int duration = 0;
> +	uint64_t hpage_size = read_pmd_pagesize();
> +	uint64_t hpage_shift = hpshift();

NIT: could be consts?

>
>  	ksft_print_header();
>
> @@ -70,23 +72,23 @@ 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 +101,7 @@ 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 +109,7 @@ 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 +125,7 @@ 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 +133,7 @@ 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 4821a3563036..4332f8fb2104 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 __hpage_size;
> +uint64_t __hpage_shift;
>
>  uint64_t pagemap_get_entry(int fd, char *start)
>  {
> @@ -161,6 +163,9 @@ uint64_t read_pmd_pagesize(void)
>  	char buf[20];
>  	ssize_t num_read;
>
> +	if (__hpage_size)
> +		return __hpage_size;
> +
>  	fd = open(PMD_SIZE_FILE_PATH, O_RDONLY);
>  	if (fd == -1)
>  		return 0;
> @@ -173,7 +178,24 @@ uint64_t read_pmd_pagesize(void)
>  	buf[num_read] = '\0';
>  	close(fd);
>
> -	return strtoul(buf, NULL, 10);
> +	__hpage_size = strtoul(buf, NULL, 10);
> +
> +	return __hpage_size;
> +}
> +
> +uint64_t hpshift(void)
> +{
> +	if (!__hpage_shift) {
> +		if (!__hpage_size) {
> +			__hpage_size = read_pmd_pagesize();
> +			if (!__hpage_size)
> +				ksft_exit_fail_msg("reading __hpage_size failed\n");
> +		}

This nesting is a bit horrifying :P

Maybe:

	if (__hpage_shift && __hpage_size)
		return;

	if (!__hpage_size) {
		...
	}

	if (!__hpage_shift) {
		...
	}

?

> +
> +		__hpage_shift = (ffsl(__hpage_size) - 1);
> +	}
> +
> +	return __hpage_shift;
>  }
>
>  unsigned long rss_anon(void)
> @@ -452,14 +474,16 @@ 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];
> +	uint64_t hpage_size = read_pmd_pagesize();
> +	uint64_t hpage_shift = hpshift();

NIT: could be const?

>
>  	/* 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 +495,7 @@ 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 9a49af88702e..20a6334605c7 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 __hpage_size;
> +extern uint64_t __hpage_shift;
>
>  /*
>   * 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 read_pmd_pagesize(void);
> +uint64_t hpshift(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)
> -

Worth calling this change out in commit msg also?

>  #define PAGEMAP_PRESENT(ent)	(((ent) & (1ull << 63)) != 0)
>  #define PAGEMAP_PFN(ent)	((ent) & ((1ull << 55) - 1))
>
> --
> LEVI:{C3F47F37-75D8-414A-A8BA-3980EC8A46D7}
>

--
Cheers, Lorenzo

Re: [PATCH] kselftest: mm: remove HPAGE_SIZE and HPAGE_SHIFT macro

[Sarthak Sharma]

Hi Yeoreum!

On 9/2/26 11:26 PM, 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 than 4KB.
>
> Here is 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 hpshift()
> helper to get the HPAGE_SHIFT properly. For HPAGE_SIZE, use pre-exist

Nit : pre-existing

> helper, read_pmd_pagesize().
> > Also, do KSM_MERGE_TIME_HUGE_PAGES test with size of 512 MiB which
> is the LCD pmd_size among 4KB, 16KB and 64KB page_size.
>
> 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>
> ---

[...]

> diff --git a/tools/testing/selftests/mm/vm_util.c b/tools/testing/selftests/mm/vm_util.c
> index 4821a3563036..4332f8fb2104 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 __hpage_size;
> +uint64_t __hpage_shift;

I was wondering, would it make more sense to call these __pmd_pagesize
and __pmd_shift instead?

hpage_size is used at places for mTHPs of arbitrary sizes and these
values come from read_pmd_pagesize(). So calling __hpage_size as the PMD
size seems a bit weird. Also, there is already a pmd_pagesize variable
in vm_util.c, so I feel the PMD specific names would be more consistent.

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Re: [PATCH] kselftest: mm: remove HPAGE_SIZE and HPAGE_SHIFT macro

[Yeoreum Yun]

> On Wed, Sep 02, 2026 at 06:56:11PM +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 than 4KB.
> >
> > Here is 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 hpshift()
> > helper to get the HPAGE_SHIFT properly. For HPAGE_SIZE, use pre-exist
> > helper, read_pmd_pagesize().
> >
> > Also, do KSM_MERGE_TIME_HUGE_PAGES test with size of 512 MiB which
> > is the LCD pmd_size among 4KB, 16KB and 64KB page_size.
> 
> Probably worth spelling out Least Common Denominator for those who might
> mistaken this for a kind of display panel :P

Bad typo :( LCM (least common multiple) :(

> 
> I also wonder if it's worth pulling that out as a separate patch in a series for
> better bisectability?

Okay. I'll separate it.

> 
> >
> > 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>
> 
> Firstly THANK YOU for doing this :) hugely appreciated.
> 
> Also thank you again for the birthday cakes ;)
> 
> And apologies for the nitpicks :P

No worries! Thanks for your comment ;)

> 
> > ---
> >  tools/testing/selftests/mm/guard-regions.c    | 12 +++++--
> >  tools/testing/selftests/mm/ksm_tests.c        | 17 ++++++----
> >  tools/testing/selftests/mm/run_vmtests.sh     |  4 +--
> >  tools/testing/selftests/mm/transhuge-stress.c | 22 +++++++------
> >  tools/testing/selftests/mm/vm_util.c          | 32 ++++++++++++++++---
> >  tools/testing/selftests/mm/vm_util.h          |  9 ++----
> >  6 files changed, 66 insertions(+), 30 deletions(-)
> >
> > diff --git a/tools/testing/selftests/mm/guard-regions.c b/tools/testing/selftests/mm/guard-regions.c
> > index 5c8ec3ca75d7..d370592b291f 100644
> > --- a/tools/testing/selftests/mm/guard-regions.c
> > +++ b/tools/testing/selftests/mm/guard-regions.c
> > @@ -2195,14 +2195,22 @@ 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;
> > +	uint64_t hpage_size;
> > +	unsigned long size;
> > +	unsigned long num_pages;
> >  	char *ptr;
> >  	int i;
> >
> >  	if (!thp_available())
> >  		SKIP(return, "Transparent Hugepages not available\n");
> >
> > +	hpage_size = read_pmd_pagesize();
> > +	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..278e77055007 100644
> > --- a/tools/testing/selftests/mm/ksm_tests.c
> > +++ b/tools/testing/selftests/mm/ksm_tests.c
> > @@ -521,6 +521,11 @@ 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;
> > +	uint64_t hpage_size = read_pmd_pagesize();
> 
> NIT: can this be const?

Acked.

> 
> > +
> > +	if (!hpage_size) {
> > +		ksft_exit_fail_msg("reading hpage_size failed\n");
> > +	}
> 
> NIT: can drop the {}

Acked.
> 
> >
> >  	if (!thp_is_enabled()) {
> >  		ksft_print_msg("Transparent Hugepages not available\n");
> > @@ -530,10 +535,10 @@ static int ksm_merge_hugepages_time(int merge_type, int mapping, int prot,
> >  	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 +552,7 @@ 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 +583,11 @@ 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 d09f9f6a384e..24aa1de27c25 100755
> > --- a/tools/testing/selftests/mm/run_vmtests.sh
> > +++ b/tools/testing/selftests/mm/run_vmtests.sh
> > @@ -360,8 +360,8 @@ 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
> 
> See above re: splitting out.

Okay. I'll split!

> 
> >  # 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..66ae94afaf8d 100644
> > --- a/tools/testing/selftests/mm/transhuge-stress.c
> > +++ b/tools/testing/selftests/mm/transhuge-stress.c
> > @@ -35,6 +35,8 @@ int main(int argc, char **argv)
> >  	size_t map_len;
> >  	int pagemap_fd;
> >  	int duration = 0;
> > +	uint64_t hpage_size = read_pmd_pagesize();
> > +	uint64_t hpage_shift = hpshift();
> 
> NIT: could be consts?

Okay.

> 
> >
> >  	ksft_print_header();
> >
> > @@ -70,23 +72,23 @@ 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 +101,7 @@ 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 +109,7 @@ 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 +125,7 @@ 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 +133,7 @@ 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 4821a3563036..4332f8fb2104 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 __hpage_size;
> > +uint64_t __hpage_shift;
> >
> >  uint64_t pagemap_get_entry(int fd, char *start)
> >  {
> > @@ -161,6 +163,9 @@ uint64_t read_pmd_pagesize(void)
> >  	char buf[20];
> >  	ssize_t num_read;
> >
> > +	if (__hpage_size)
> > +		return __hpage_size;
> > +
> >  	fd = open(PMD_SIZE_FILE_PATH, O_RDONLY);
> >  	if (fd == -1)
> >  		return 0;
> > @@ -173,7 +178,24 @@ uint64_t read_pmd_pagesize(void)
> >  	buf[num_read] = '\0';
> >  	close(fd);
> >
> > -	return strtoul(buf, NULL, 10);
> > +	__hpage_size = strtoul(buf, NULL, 10);
> > +
> > +	return __hpage_size;
> > +}
> > +
> > +uint64_t hpshift(void)
> > +{
> > +	if (!__hpage_shift) {
> > +		if (!__hpage_size) {
> > +			__hpage_size = read_pmd_pagesize();
> > +			if (!__hpage_size)
> > +				ksft_exit_fail_msg("reading __hpage_size failed\n");
> > +		}
> 
> This nesting is a bit horrifying :P
> 
> Maybe:
> 
> 	if (__hpage_shift && __hpage_size)
> 		return;
> 
> 	if (!__hpage_size) {
> 		...
> 	}
> 
> 	if (!__hpage_shift) {
> 		...
> 	}
> 
> ?

I see. I'll untie the nesting.

> 
> > +
> > +		__hpage_shift = (ffsl(__hpage_size) - 1);
> > +	}
> > +
> > +	return __hpage_shift;
> >  }
> >
> >  unsigned long rss_anon(void)
> > @@ -452,14 +474,16 @@ 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];
> > +	uint64_t hpage_size = read_pmd_pagesize();
> > +	uint64_t hpage_shift = hpshift();
> 
> NIT: could be const?

Okay ;)

> 
> >
> >  	/* 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 +495,7 @@ 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 9a49af88702e..20a6334605c7 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 __hpage_size;
> > +extern uint64_t __hpage_shift;
> >
> >  /*
> >   * 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 read_pmd_pagesize(void);
> > +uint64_t hpshift(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)
> > -
> 
> Worth calling this change out in commit msg also?

It was spelled out as They're removed ;).

> 
> >  #define PAGEMAP_PRESENT(ent)	(((ent) & (1ull << 63)) != 0)
> >  #define PAGEMAP_PFN(ent)	((ent) & ((1ull << 55) - 1))
> >
> > --
> > LEVI:{C3F47F37-75D8-414A-A8BA-3980EC8A46D7}
> >
> 
> --

Thanks!

-- 
Sincerely,
Yeoreum Yun

Re: [PATCH] kselftest: mm: remove HPAGE_SIZE and HPAGE_SHIFT macro

[Yeoreum Yun]

Hi Sarthak,

> Hi Yeoreum!
> 
> On 9/2/26 11:26 PM, 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 than 4KB.
> > 
> > Here is 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 hpshift()
> > helper to get the HPAGE_SHIFT properly. For HPAGE_SIZE, use pre-exist
> 
> Nit : pre-existing

Sorry for typo ;)

> 
> > helper, read_pmd_pagesize().
> > > Also, do KSM_MERGE_TIME_HUGE_PAGES test with size of 512 MiB which
> > is the LCD pmd_size among 4KB, 16KB and 64KB page_size.
> > 
> > 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>
> > ---
> 
> [...]
> 
> > diff --git a/tools/testing/selftests/mm/vm_util.c b/tools/testing/selftests/mm/vm_util.c
> > index 4821a3563036..4332f8fb2104 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 __hpage_size;
> > +uint64_t __hpage_shift;
> 
> I was wondering, would it make more sense to call these __pmd_pagesize
> and __pmd_shift instead?
> 
> hpage_size is used at places for mTHPs of arbitrary sizes and these
> values come from read_pmd_pagesize(). So calling __hpage_size as the PMD
> size seems a bit weird. Also, there is already a pmd_pagesize variable
> in vm_util.c, so I feel the PMD specific names would be more consistent.

That seems better. Thanks!

-- 
Sincerely,
Yeoreum Yun

Re: [PATCH] kselftest: mm: remove HPAGE_SIZE and HPAGE_SHIFT macro

[Yeoreum Yun]

> > On Wed, Sep 02, 2026 at 06:56:11PM +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 than 4KB.
> > >
> > > Here is 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 hpshift()
> > > helper to get the HPAGE_SHIFT properly. For HPAGE_SIZE, use pre-exist
> > > helper, read_pmd_pagesize().
> > >
> > > Also, do KSM_MERGE_TIME_HUGE_PAGES test with size of 512 MiB which
> > > is the LCD pmd_size among 4KB, 16KB and 64KB page_size.
> > 
> > Probably worth spelling out Least Common Denominator for those who might
> > mistaken this for a kind of display panel :P
> 
> Bad typo :( LCM (least common multiple) :(
> 
> > 
> > I also wonder if it's worth pulling that out as a separate patch in a series for
> > better bisectability?
> 
> Okay. I'll separate it.

Hmm, I think it would be better to keep the change as is, including the
updated ksm_tests parameter. Although allocate_transhuge() correctly
allocates mappings aligned to the PMD page size, `ksm_tests -H -s 100`
would otherwise fail because 100 MiB is not a multiple of the PMD page
size.

[...]

-- 
Sincerely,
Yeoreum Yun

Re: [PATCH] kselftest: mm: remove HPAGE_SIZE and HPAGE_SHIFT macro

[Lorenzo Stoakes (ARM)]

On Thu, Sep 03, 2026 at 03:46:20PM +0100, Yeoreum Yun wrote:
> > > On Wed, Sep 02, 2026 at 06:56:11PM +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 than 4KB.
> > > >
> > > > Here is 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 hpshift()
> > > > helper to get the HPAGE_SHIFT properly. For HPAGE_SIZE, use pre-exist
> > > > helper, read_pmd_pagesize().
> > > >
> > > > Also, do KSM_MERGE_TIME_HUGE_PAGES test with size of 512 MiB which
> > > > is the LCD pmd_size among 4KB, 16KB and 64KB page_size.
> > >
> > > Probably worth spelling out Least Common Denominator for those who might
> > > mistaken this for a kind of display panel :P
> >
> > Bad typo :( LCM (least common multiple) :(
> >
> > >
> > > I also wonder if it's worth pulling that out as a separate patch in a series for
> > > better bisectability?
> >
> > Okay. I'll separate it.
>
> Hmm, I think it would be better to keep the change as is, including the
> updated ksm_tests parameter. Although allocate_transhuge() correctly
> allocates mappings aligned to the PMD page size, `ksm_tests -H -s 100`
> would otherwise fail because 100 MiB is not a multiple of the PMD page
> size.

OK, just add a note about it in the commit msg :)

>
> [...]
>
> --
> Sincerely,
> Yeoreum Yun

--
Cheers, Lorenzo