[PATCH v2 0/3] selftests/mm: pagemap_ioctl test fixes and cleanups

[PATCH v2 0/3] selftests/mm: pagemap_ioctl test fixes and cleanups

[Zenghui Yu]

From: "Zenghui Yu (Huawei)" <zenghui.yu@linux.dev>

This series fixes a size truncation bug in the pagemap_ioctl test that
breaks it on arm64 systems with 64K base pages, and applies two small
cleanups suggested during the review of the fix.

* From v1 [1]:
  - unify all size-related parameters and variables to size_t (David)
  - drop Gregory's R-b for patch #1 (as the content has changed too much)
    but thank you for that!
  - add patch #2 marking file-local symbols static (David)
  - add patch #3 initializing page sizes early (Andrew)

[1] https://lore.kernel.org/20260907135613.68692-1-zenghui.yu@linux.dev

Zenghui Yu (Huawei) (3):
  selftests/mm: fix size truncation in pagemap_ioctl test
  selftests/mm: mark file-local symbols of pagemap_ioctl.c static
  selftests/mm: init page sizes early in pagemap_ioctl test

 tools/testing/selftests/mm/pagemap_ioctl.c | 94 +++++++++++-----------
 1 file changed, 48 insertions(+), 46 deletions(-)

-- 
2.53.0

[PATCH v2 1/3] selftests/mm: fix size truncation in pagemap_ioctl test

[Zenghui Yu]

From: "Zenghui Yu (Huawei)" <zenghui.yu@linux.dev>

On arm64 with 64K base pages, the huge page size is 512 MiB, and
hpage_unit_tests() builds a 5 GiB range (10 * 512 MiB) for its tests.  This
exceeds the range of the int size parameters of gethugepage(),
wp_addr_range() and pagemap_ioctl().  The implicit truncation to 1 GiB
makes gethugepage() allocate a too small buffer, while the callers keep
operating on the original 5 GiB range, resulting in spurious failures or
SIGSEGV.

Fix the truncation by changing those size parameters to size_t, and for
consistency, also convert the remaining size-related parameters and
variables that use int, long or unsigned long long to size_t.

Fixes: 46fd75d4a3c9 ("selftests: mm: add pagemap ioctl tests")
Assisted-by: GLM-5.3 OpenCode
Suggested-by: David Hildenbrand (Arm) <david@kernel.org>
Signed-off-by: Zenghui Yu (Huawei) <zenghui.yu@linux.dev>
---
 tools/testing/selftests/mm/pagemap_ioctl.c | 55 ++++++++++++----------
 1 file changed, 29 insertions(+), 26 deletions(-)

diff --git a/tools/testing/selftests/mm/pagemap_ioctl.c b/tools/testing/selftests/mm/pagemap_ioctl.c
index eadc7159ca5b..3665530eda76 100644
--- a/tools/testing/selftests/mm/pagemap_ioctl.c
+++ b/tools/testing/selftests/mm/pagemap_ioctl.c
@@ -44,7 +44,7 @@ const char *progname;
 
 #define LEN(region)	((region.end - region.start)/page_size)
 
-static long pagemap_ioctl(void *start, int len, void *vec, int vec_len, int flag,
+static long pagemap_ioctl(void *start, size_t len, void *vec, size_t vec_len, int flag,
 			  int max_pages, long required_mask, long anyof_mask, long excluded_mask,
 			  long return_mask)
 {
@@ -65,7 +65,7 @@ static long pagemap_ioctl(void *start, int len, void *vec, int vec_len, int flag
 	return ioctl(pagemap_fd, PAGEMAP_SCAN, &arg);
 }
 
-static long pagemap_ioc(void *start, int len, void *vec, int vec_len, int flag,
+static long pagemap_ioc(void *start, size_t len, void *vec, size_t vec_len, int flag,
 			int max_pages, long required_mask, long anyof_mask, long excluded_mask,
 			long return_mask, long *walk_end)
 {
@@ -116,7 +116,7 @@ int init_uffd(void)
 	return 0;
 }
 
-int wp_init(void *addr, long size)
+int wp_init(void *addr, size_t size)
 {
 	struct uffdio_register uffdio_register;
 	struct uffdio_writeprotect wp;
@@ -140,7 +140,7 @@ int wp_init(void *addr, long size)
 	return 0;
 }
 
-int wp_free(void *addr, long size)
+int wp_free(void *addr, size_t size)
 {
 	struct uffdio_register uffdio_register;
 
@@ -152,7 +152,7 @@ int wp_free(void *addr, long size)
 	return 0;
 }
 
-int wp_addr_range(void *addr, int size)
+int wp_addr_range(void *addr, size_t size)
 {
 	if (pagemap_ioctl(addr, size, NULL, 0,
 			  PM_SCAN_WP_MATCHING | PM_SCAN_CHECK_WPASYNC,
@@ -162,7 +162,7 @@ int wp_addr_range(void *addr, int size)
 	return 0;
 }
 
-void *gethugetlb_mem(int size, int *shmid)
+void *gethugetlb_mem(size_t size, int *shmid)
 {
 	char *mem;
 
@@ -188,7 +188,8 @@ void *gethugetlb_mem(int size, int *shmid)
 
 int userfaultfd_tests(void)
 {
-	long mem_size, vec_size, written, num_pages = 16;
+	size_t mem_size, vec_size, num_pages = 16;
+	long written;
 	char *mem, *vec;
 
 	mem_size = num_pages * page_size;
@@ -229,9 +230,10 @@ int userfaultfd_tests(void)
 	return 0;
 }
 
-int get_reads(struct page_region *vec, int vec_size)
+int get_reads(struct page_region *vec, size_t vec_size)
 {
-	int i, sum = 0;
+	size_t i;
+	int sum = 0;
 
 	for (i = 0; i < vec_size; i++)
 		sum += LEN(vec[i]);
@@ -241,7 +243,7 @@ int get_reads(struct page_region *vec, int vec_size)
 
 int sanity_tests_sd(void)
 {
-	unsigned long long mem_size, vec_size, i, total_pages = 0;
+	size_t mem_size, vec_size, i, total_pages = 0;
 	long ret, ret2, ret3;
 	int num_pages = 1000;
 	int total_writes, total_reads, reads, count;
@@ -331,7 +333,7 @@ int sanity_tests_sd(void)
 	if (ret < 0)
 		ksft_exit_fail_msg("error %ld %d %s\n", ret, errno, strerror(errno));
 
-	ksft_test_result((unsigned long long)ret == mem_size/(page_size * 2),
+	ksft_test_result((size_t)ret == mem_size/(page_size * 2),
 			 "%s Repeated pattern of written and non-written pages\n", __func__);
 
 	/* 4. Repeated pattern of written and non-written pages in parts */
@@ -682,9 +684,9 @@ int sanity_tests_sd(void)
 	return 0;
 }
 
-int base_tests(char *prefix, char *mem, unsigned long long mem_size, int skip)
+int base_tests(char *prefix, char *mem, size_t mem_size, int skip)
 {
-	unsigned long long vec_size;
+	size_t vec_size;
 	int written;
 	struct page_region *vec, *vec2;
 
@@ -787,7 +789,7 @@ int base_tests(char *prefix, char *mem, unsigned long long mem_size, int skip)
 	return 0;
 }
 
-void *gethugepage(int map_size)
+void *gethugepage(size_t map_size)
 {
 	int ret;
 	char *map;
@@ -810,8 +812,8 @@ int hpage_unit_tests(void)
 	char *map;
 	int ret, ret2;
 	size_t num_pages = 10;
-	unsigned long long map_size = hpage_size * num_pages;
-	unsigned long long vec_size = map_size/page_size;
+	size_t map_size = hpage_size * num_pages;
+	size_t vec_size = map_size/page_size;
 	struct page_region *vec, *vec2;
 
 	vec = calloc(vec_size, sizeof(struct page_region));
@@ -1002,8 +1004,9 @@ int hpage_unit_tests(void)
 int unmapped_region_tests(void)
 {
 	void *start = (void *)0x10000000;
-	int written, len = 0x00040000;
-	long vec_size = len / page_size;
+	int written;
+	size_t len = 0x00040000;
+	size_t vec_size = len / page_size;
 	struct page_region *vec = calloc(vec_size, sizeof(struct page_region));
 	if (!vec)
 		ksft_exit_fail_msg("error nomem\n");
@@ -1072,7 +1075,7 @@ static void test_simple(void)
  * with no page table, exercising pagemap_scan_pte_hole(); a base-page range
  * leaves pte_none entries.
  */
-static void unpopulated_written_test(const char *name, char *mem, long size,
+static void unpopulated_written_test(const char *name, char *mem, size_t size,
 				     bool use_thp)
 {
 	long npages = size / page_size, fast = 0, slow = 0, ret;
@@ -1115,7 +1118,7 @@ static void unpopulated_written_test(const char *name, char *mem, long size,
 
 static void unpopulated_scan_test(void)
 {
-	long mem_size = 16 * page_size;
+	size_t mem_size = 16 * page_size;
 	char *mem;
 
 	mem = mmap(NULL, mem_size, PROT_READ | PROT_WRITE,
@@ -1157,8 +1160,8 @@ static void unpopulated_thp_scan_test(void)
 
 int sanity_tests(void)
 {
-	unsigned long long mem_size, vec_size;
-	long ret, fd, i, buf_size, nr_pages;
+	size_t mem_size, vec_size, i, buf_size;
+	long ret, fd, nr_pages;
 	struct page_region *vec;
 	char *mem, *fmem;
 	struct stat sbuf;
@@ -1582,9 +1585,9 @@ static void transact_test(int page_size)
 
 void zeropfn_tests(void)
 {
-	unsigned long long mem_size;
+	size_t mem_size, i;
 	struct page_region vec;
-	int i, ret;
+	int ret;
 	char *mmap_mem, *mem;
 
 	/* Test with normal memory */
@@ -1642,8 +1645,8 @@ void zeropfn_tests(void)
 
 int main(int __attribute__((unused)) argc, char *argv[])
 {
-	int shmid, buf_size, fd, i, ret;
-	unsigned long long mem_size;
+	int shmid, fd, ret;
+	size_t mem_size, buf_size, i;
 	char *mem, *map, *fmem;
 	struct stat sbuf;
 
-- 
2.53.0

Re: [PATCH v2 1/3] selftests/mm: fix size truncation in pagemap_ioctl test

[David Hildenbrand (Arm)]

On 9/8/26 15:41, Zenghui Yu wrote:
> From: "Zenghui Yu (Huawei)" <zenghui.yu@linux.dev>
> 
> On arm64 with 64K base pages, the huge page size is 512 MiB, and
> hpage_unit_tests() builds a 5 GiB range (10 * 512 MiB) for its tests.  This
> exceeds the range of the int size parameters of gethugepage(),
> wp_addr_range() and pagemap_ioctl().  The implicit truncation to 1 GiB
> makes gethugepage() allocate a too small buffer, while the callers keep
> operating on the original 5 GiB range, resulting in spurious failures or
> SIGSEGV.
> 
> Fix the truncation by changing those size parameters to size_t, and for
> consistency, also convert the remaining size-related parameters and
> variables that use int, long or unsigned long long to size_t.
> 
> Fixes: 46fd75d4a3c9 ("selftests: mm: add pagemap ioctl tests")
> Assisted-by: GLM-5.3 OpenCode
> Suggested-by: David Hildenbrand (Arm) <david@kernel.org>
> Signed-off-by: Zenghui Yu (Huawei) <zenghui.yu@linux.dev>
> ---

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

-- 
Cheers,

David

[PATCH v2 2/3] selftests/mm: mark file-local symbols of pagemap_ioctl.c static

[Zenghui Yu]

From: "Zenghui Yu (Huawei)" <zenghui.yu@linux.dev>

The file-scope variables (pagemap_fd, uffd, page_size, hpage_size and
progname) and most functions of the pagemap_ioctl test are only used
locally, but lack the static storage class.  Mark them static so that the
compiler can catch accidental outer references.

Suggested-by: David Hildenbrand (Arm) <david@kernel.org>
Signed-off-by: Zenghui Yu (Huawei) <zenghui.yu@linux.dev>
---
 tools/testing/selftests/mm/pagemap_ioctl.c | 43 +++++++++++-----------
 1 file changed, 21 insertions(+), 22 deletions(-)

diff --git a/tools/testing/selftests/mm/pagemap_ioctl.c b/tools/testing/selftests/mm/pagemap_ioctl.c
index 3665530eda76..1a87b7483316 100644
--- a/tools/testing/selftests/mm/pagemap_ioctl.c
+++ b/tools/testing/selftests/mm/pagemap_ioctl.c
@@ -36,11 +36,11 @@
 
 #define TEST_ITERATIONS 100
 #define PAGEMAP "/proc/self/pagemap"
-int pagemap_fd;
-int uffd;
-size_t page_size;
-size_t hpage_size;
-const char *progname;
+static int pagemap_fd;
+static int uffd;
+static size_t page_size;
+static size_t hpage_size;
+static const char *progname;
 
 #define LEN(region)	((region.end - region.start)/page_size)
 
@@ -92,8 +92,7 @@ static long pagemap_ioc(void *start, size_t len, void *vec, size_t vec_len, int
 	return ret;
 }
 
-
-int init_uffd(void)
+static int init_uffd(void)
 {
 	struct uffdio_api uffdio_api;
 
@@ -116,7 +115,7 @@ int init_uffd(void)
 	return 0;
 }
 
-int wp_init(void *addr, size_t size)
+static int wp_init(void *addr, size_t size)
 {
 	struct uffdio_register uffdio_register;
 	struct uffdio_writeprotect wp;
@@ -140,7 +139,7 @@ int wp_init(void *addr, size_t size)
 	return 0;
 }
 
-int wp_free(void *addr, size_t size)
+static int wp_free(void *addr, size_t size)
 {
 	struct uffdio_register uffdio_register;
 
@@ -152,7 +151,7 @@ int wp_free(void *addr, size_t size)
 	return 0;
 }
 
-int wp_addr_range(void *addr, size_t size)
+static int wp_addr_range(void *addr, size_t size)
 {
 	if (pagemap_ioctl(addr, size, NULL, 0,
 			  PM_SCAN_WP_MATCHING | PM_SCAN_CHECK_WPASYNC,
@@ -162,7 +161,7 @@ int wp_addr_range(void *addr, size_t size)
 	return 0;
 }
 
-void *gethugetlb_mem(size_t size, int *shmid)
+static void *gethugetlb_mem(size_t size, int *shmid)
 {
 	char *mem;
 
@@ -186,7 +185,7 @@ void *gethugetlb_mem(size_t size, int *shmid)
 	return mem;
 }
 
-int userfaultfd_tests(void)
+static int userfaultfd_tests(void)
 {
 	size_t mem_size, vec_size, num_pages = 16;
 	long written;
@@ -230,7 +229,7 @@ int userfaultfd_tests(void)
 	return 0;
 }
 
-int get_reads(struct page_region *vec, size_t vec_size)
+static int get_reads(struct page_region *vec, size_t vec_size)
 {
 	size_t i;
 	int sum = 0;
@@ -241,7 +240,7 @@ int get_reads(struct page_region *vec, size_t vec_size)
 	return sum;
 }
 
-int sanity_tests_sd(void)
+static int sanity_tests_sd(void)
 {
 	size_t mem_size, vec_size, i, total_pages = 0;
 	long ret, ret2, ret3;
@@ -684,7 +683,7 @@ int sanity_tests_sd(void)
 	return 0;
 }
 
-int base_tests(char *prefix, char *mem, size_t mem_size, int skip)
+static int base_tests(char *prefix, char *mem, size_t mem_size, int skip)
 {
 	size_t vec_size;
 	int written;
@@ -789,7 +788,7 @@ int base_tests(char *prefix, char *mem, size_t mem_size, int skip)
 	return 0;
 }
 
-void *gethugepage(size_t map_size)
+static void *gethugepage(size_t map_size)
 {
 	int ret;
 	char *map;
@@ -807,7 +806,7 @@ void *gethugepage(size_t map_size)
 	return map;
 }
 
-int hpage_unit_tests(void)
+static int hpage_unit_tests(void)
 {
 	char *map;
 	int ret, ret2;
@@ -1001,7 +1000,7 @@ int hpage_unit_tests(void)
 	return 0;
 }
 
-int unmapped_region_tests(void)
+static int unmapped_region_tests(void)
 {
 	void *start = (void *)0x10000000;
 	int written;
@@ -1158,7 +1157,7 @@ static void unpopulated_thp_scan_test(void)
 	munmap(area, 2 * hpage_size);
 }
 
-int sanity_tests(void)
+static int sanity_tests(void)
 {
 	size_t mem_size, vec_size, i, buf_size;
 	long ret, fd, nr_pages;
@@ -1330,7 +1329,7 @@ int sanity_tests(void)
 	return 0;
 }
 
-int mprotect_tests(void)
+static int mprotect_tests(void)
 {
 	int ret;
 	char *mem, *mem2;
@@ -1450,7 +1449,7 @@ static ssize_t get_dirty_pages_reset(char *mem, unsigned int count,
 	return cnt;
 }
 
-void *thread_proc(void *mem)
+static void *thread_proc(void *mem)
 {
 	int *m = mem;
 	long curr_faults, faults;
@@ -1583,7 +1582,7 @@ static void transact_test(int page_size)
 			      extra_thread_faults);
 }
 
-void zeropfn_tests(void)
+static void zeropfn_tests(void)
 {
 	size_t mem_size, i;
 	struct page_region vec;
-- 
2.53.0

Re: [PATCH v2 2/3] selftests/mm: mark file-local symbols of pagemap_ioctl.c static

[David Hildenbrand (Arm)]

On 9/8/26 15:43, Zenghui Yu wrote:
> From: "Zenghui Yu (Huawei)" <zenghui.yu@linux.dev>
> 
> The file-scope variables (pagemap_fd, uffd, page_size, hpage_size and
> progname) and most functions of the pagemap_ioctl test are only used
> locally, but lack the static storage class.  Mark them static so that the
> compiler can catch accidental outer references.
> 
> Suggested-by: David Hildenbrand (Arm) <david@kernel.org>
> Signed-off-by: Zenghui Yu (Huawei) <zenghui.yu@linux.dev>
> ---

Thanks!

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

-- 
Cheers,

David

[PATCH v2 3/3] selftests/mm: init page sizes early in pagemap_ioctl test

[Zenghui Yu]

From: "Zenghui Yu (Huawei)" <zenghui.yu@linux.dev>

Initialize page_size and hpage_size before calling init_uffd(),
hugetlb_setup_default(), etc.  That won't fix anything, but it is safer and
saner to get these globals set up before doing other things.

While at it, drop the page_size parameter of transact_test(), which is
actually unnecessary.

Suggested-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Zenghui Yu (Huawei) <zenghui.yu@linux.dev>
---
 tools/testing/selftests/mm/pagemap_ioctl.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/tools/testing/selftests/mm/pagemap_ioctl.c b/tools/testing/selftests/mm/pagemap_ioctl.c
index 1a87b7483316..d9a4fb782ecf 100644
--- a/tools/testing/selftests/mm/pagemap_ioctl.c
+++ b/tools/testing/selftests/mm/pagemap_ioctl.c
@@ -1489,7 +1489,7 @@ static void *thread_proc(void *mem)
 	return NULL;
 }
 
-static void transact_test(int page_size)
+static void transact_test(void)
 {
 	unsigned int i, count, extra_pages;
 	unsigned int c;
@@ -1653,6 +1653,9 @@ int main(int __attribute__((unused)) argc, char *argv[])
 
 	ksft_print_header();
 
+	page_size = getpagesize();
+	hpage_size = read_pmd_pagesize();
+
 	if (init_uffd())
 		ksft_exit_skip("Failed to initialize userfaultfd\n");
 
@@ -1661,9 +1664,6 @@ int main(int __attribute__((unused)) argc, char *argv[])
 
 	ksft_set_plan(119);
 
-	page_size = getpagesize();
-	hpage_size = read_pmd_pagesize();
-
 	pagemap_fd = open(PAGEMAP, O_RDONLY);
 	if (pagemap_fd < 0)
 		ksft_exit_fail_msg("Failed to open " PAGEMAP "\n");
@@ -1823,7 +1823,7 @@ int main(int __attribute__((unused)) argc, char *argv[])
 	mprotect_tests();
 
 	/* 13. Transact test */
-	transact_test(page_size);
+	transact_test();
 
 	/* 14. Sanity testing */
 	sanity_tests();
-- 
2.53.0

Re: [PATCH v2 3/3] selftests/mm: init page sizes early in pagemap_ioctl test

[Zenghui Yu]

On 9/8/26 9:44 PM, Zenghui Yu wrote:
> From: "Zenghui Yu (Huawei)" <zenghui.yu@linux.dev>
> 
> Initialize page_size and hpage_size before calling init_uffd(),
> hugetlb_setup_default(), etc.  That won't fix anything, but it is safer and
> saner to get these globals set up before doing other things.
> 
> While at it, drop the page_size parameter of transact_test(), which is
> actually unnecessary.
> 
> Suggested-by: Andrew Morton <akpm@linux-foundation.org>

See https://lore.kernel.org/20260628111329.9cfcd9c67925869307020aba@linux-foundation.org/ .

> Signed-off-by: Zenghui Yu (Huawei) <zenghui.yu@linux.dev>
> ---
>  tools/testing/selftests/mm/pagemap_ioctl.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/tools/testing/selftests/mm/pagemap_ioctl.c b/tools/testing/selftests/mm/pagemap_ioctl.c
> index 1a87b7483316..d9a4fb782ecf 100644
> --- a/tools/testing/selftests/mm/pagemap_ioctl.c
> +++ b/tools/testing/selftests/mm/pagemap_ioctl.c
> @@ -1489,7 +1489,7 @@ static void *thread_proc(void *mem)
>  	return NULL;
>  }
>  
> -static void transact_test(int page_size)
> +static void transact_test(void)
>  {
>  	unsigned int i, count, extra_pages;
>  	unsigned int c;
> @@ -1653,6 +1653,9 @@ int main(int __attribute__((unused)) argc, char *argv[])
>  
>  	ksft_print_header();
>  
> +	page_size = getpagesize();
> +	hpage_size = read_pmd_pagesize();
> +
>  	if (init_uffd())
>  		ksft_exit_skip("Failed to initialize userfaultfd\n");
>  
> @@ -1661,9 +1664,6 @@ int main(int __attribute__((unused)) argc, char *argv[])
>  
>  	ksft_set_plan(119);
>  
> -	page_size = getpagesize();
> -	hpage_size = read_pmd_pagesize();
> -
>  	pagemap_fd = open(PAGEMAP, O_RDONLY);
>  	if (pagemap_fd < 0)
>  		ksft_exit_fail_msg("Failed to open " PAGEMAP "\n");
> @@ -1823,7 +1823,7 @@ int main(int __attribute__((unused)) argc, char *argv[])
>  	mprotect_tests();
>  
>  	/* 13. Transact test */
> -	transact_test(page_size);
> +	transact_test();
>  
>  	/* 14. Sanity testing */
>  	sanity_tests();

Re: [PATCH v2 3/3] selftests/mm: init page sizes early in pagemap_ioctl test

[David Hildenbrand (Arm)]

On 9/8/26 15:44, Zenghui Yu wrote:
> From: "Zenghui Yu (Huawei)" <zenghui.yu@linux.dev>
> 
> Initialize page_size and hpage_size before calling init_uffd(),
> hugetlb_setup_default(), etc.  That won't fix anything, but it is safer and
> saner to get these globals set up before doing other things.
> 
> While at it, drop the page_size parameter of transact_test(), which is
> actually unnecessary.
> 
> Suggested-by: Andrew Morton <akpm@linux-foundation.org>
> Signed-off-by: Zenghui Yu (Huawei) <zenghui.yu@linux.dev>
> ---
>  tools/testing/selftests/mm/pagemap_ioctl.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/tools/testing/selftests/mm/pagemap_ioctl.c b/tools/testing/selftests/mm/pagemap_ioctl.c
> index 1a87b7483316..d9a4fb782ecf 100644
> --- a/tools/testing/selftests/mm/pagemap_ioctl.c
> +++ b/tools/testing/selftests/mm/pagemap_ioctl.c
> @@ -1489,7 +1489,7 @@ static void *thread_proc(void *mem)
>  	return NULL;
>  }
>  
> -static void transact_test(int page_size)
> +static void transact_test(void)
>  {
>  	unsigned int i, count, extra_pages;
>  	unsigned int c;
> @@ -1653,6 +1653,9 @@ int main(int __attribute__((unused)) argc, char *argv[])
>  
>  	ksft_print_header();
>  
> +	page_size = getpagesize();
> +	hpage_size = read_pmd_pagesize();
> +
>  	if (init_uffd())
>  		ksft_exit_skip("Failed to initialize userfaultfd\n");
>  
> @@ -1661,9 +1664,6 @@ int main(int __attribute__((unused)) argc, char *argv[])
>  
>  	ksft_set_plan(119);
>  
> -	page_size = getpagesize();
> -	hpage_size = read_pmd_pagesize();
> -
We have some other code rework that part, so I expect some conflicts for whoever
goes in first.

Why not

initialize them right when defining the variables, marking them const?

-- 
Cheers,

David

Re: [PATCH v2 3/3] selftests/mm: init page sizes early in pagemap_ioctl test

[Zenghui Yu]

Hi David,

On 9/16/26 11:30 PM, David Hildenbrand (Arm) wrote:
> On 9/8/26 15:44, Zenghui Yu wrote:
> > From: "Zenghui Yu (Huawei)" <zenghui.yu@linux.dev>
> >
> > Initialize page_size and hpage_size before calling init_uffd(),
> > hugetlb_setup_default(), etc.  That won't fix anything, but it is safer and
> > saner to get these globals set up before doing other things.
> >
> > While at it, drop the page_size parameter of transact_test(), which is
> > actually unnecessary.
> >
> > Suggested-by: Andrew Morton <akpm@linux-foundation.org>
> > Signed-off-by: Zenghui Yu (Huawei) <zenghui.yu@linux.dev>
> > ---
> >  tools/testing/selftests/mm/pagemap_ioctl.c | 10 +++++-----
> >  1 file changed, 5 insertions(+), 5 deletions(-)
> >
> > diff --git a/tools/testing/selftests/mm/pagemap_ioctl.c b/tools/testing/selftests/mm/pagemap_ioctl.c
> > index 1a87b7483316..d9a4fb782ecf 100644
> > --- a/tools/testing/selftests/mm/pagemap_ioctl.c
> > +++ b/tools/testing/selftests/mm/pagemap_ioctl.c
> > @@ -1489,7 +1489,7 @@ static void *thread_proc(void *mem)
> >  	return NULL;
> >  }
> >  
> > -static void transact_test(int page_size)
> > +static void transact_test(void)
> >  {
> >  	unsigned int i, count, extra_pages;
> >  	unsigned int c;
> > @@ -1653,6 +1653,9 @@ int main(int __attribute__((unused)) argc, char *argv[])
> >  
> >  	ksft_print_header();
> >  
> > +	page_size = getpagesize();
> > +	hpage_size = read_pmd_pagesize();
> > +
> >  	if (init_uffd())
> >  		ksft_exit_skip("Failed to initialize userfaultfd\n");
> >  
> > @@ -1661,9 +1664,6 @@ int main(int __attribute__((unused)) argc, char *argv[])
> >  
> >  	ksft_set_plan(119);
> >  
> > -	page_size = getpagesize();
> > -	hpage_size = read_pmd_pagesize();
> > -
> We have some other code rework that part, so I expect some conflicts for whoever
> goes in first.
> 
> Why not
> 
> initialize them right when defining the variables, marking them const?

I'm afraid I don't quite understand your suggestion.  page_size and
hpage_size are static global variables which cannot be initialized at their
definition.  What am I missing?

Thanks,
Zenghui