selftests/mm: fix size truncation in pagemap_ioctl test

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

Posted by Zenghui Yu 2 weeks, 4 days ago

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.

Change those size parameters to size_t.

Fixes: 46fd75d4a3c9 ("selftests: mm: add pagemap ioctl tests")
Assisted-by: GLM-5.3 OpenCode
Signed-off-by: Zenghui Yu (Huawei) <zenghui.yu@linux.dev>
---
 tools/testing/selftests/mm/pagemap_ioctl.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/tools/testing/selftests/mm/pagemap_ioctl.c b/tools/testing/selftests/mm/pagemap_ioctl.c
index eadc7159ca5b..48cbea3a33c9 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, int vec_len, int flag,
 			  int max_pages, long required_mask, long anyof_mask, long excluded_mask,
 			  long return_mask)
 {
@@ -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,
@@ -787,7 +787,7 @@ 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;
-- 
2.53.0

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

Posted by David Hildenbrand (Arm) 2 weeks, 4 days ago

On 9/7/26 15:56, 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.
> 
> Change those size parameters to size_t.
> 
> Fixes: 46fd75d4a3c9 ("selftests: mm: add pagemap ioctl tests")
> Assisted-by: GLM-5.3 OpenCode
> Signed-off-by: Zenghui Yu (Huawei) <zenghui.yu@linux.dev>
> ---

Looking at pagemap_ioctl.c ... I think most functions should actually be "static".


Using size_t is ok. But then we should also change "unsigned long long mem_size"
to size_t, no?

Also, in wp_free() we are suddenly using "long size". In pagemap_ioc() we're
also still using "int len".

Can we consistently use one type please?

-- 
Cheers,

David

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

Posted by Zenghui Yu 2 weeks, 3 days ago

On 9/7/26 11:22 PM, David Hildenbrand (Arm) wrote:
> On 9/7/26 15:56, 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.
> >
> > Change those size parameters to size_t.
> >
> > Fixes: 46fd75d4a3c9 ("selftests: mm: add pagemap ioctl tests")
> > Assisted-by: GLM-5.3 OpenCode
> > Signed-off-by: Zenghui Yu (Huawei) <zenghui.yu@linux.dev>
> > ---
> 
> Looking at pagemap_ioctl.c ... I think most functions should actually be "static".

Yup.

> Using size_t is ok. But then we should also change "unsigned long long mem_size"
> to size_t, no?
> 
> Also, in wp_free() we are suddenly using "long size". In pagemap_ioc() we're
> also still using "int len".
> 
> Can we consistently use one type please?

Yes we can.  This patch adopts a minimal fix for this specific issue.  I'll
unify all size-related parameters and variables to size_t in v2.

Thanks,
Zenghui

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

Posted by David Hildenbrand (Arm) 2 weeks, 3 days ago

On 9/8/26 13:22, Zenghui Yu wrote:
> On 9/7/26 11:22 PM, David Hildenbrand (Arm) wrote:
>> On 9/7/26 15:56, 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.
>>>
>>> Change those size parameters to size_t.
>>>
>>> Fixes: 46fd75d4a3c9 ("selftests: mm: add pagemap ioctl tests")
>>> Assisted-by: GLM-5.3 OpenCode
>>> Signed-off-by: Zenghui Yu (Huawei) <zenghui.yu@linux.dev>
>>> ---
>>
>> Looking at pagemap_ioctl.c ... I think most functions should actually be "static".
> 
> Yup.
> 
>> Using size_t is ok. But then we should also change "unsigned long long mem_size"
>> to size_t, no?
>>
>> Also, in wp_free() we are suddenly using "long size". In pagemap_ioc() we're
>> also still using "int len".
>>
>> Can we consistently use one type please?
> 
> Yes we can.  This patch adopts a minimal fix for this specific issue.

Right, but for this selftest in particular we don't need a minimal fix. :)

-- 
Cheers,

David

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

Posted by Gregory Price 2 weeks, 4 days ago

On Mon, Sep 07, 2026 at 09:56:13PM +0800, 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.
> 
> Change those size parameters to size_t.
> 
> Fixes: 46fd75d4a3c9 ("selftests: mm: add pagemap ioctl tests")
> Assisted-by: GLM-5.3 OpenCode
> Signed-off-by: Zenghui Yu (Huawei) <zenghui.yu@linux.dev>

Reviewed-by: Gregory Price (Meta) <gourry@gourry.net>

> ---
>  tools/testing/selftests/mm/pagemap_ioctl.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/tools/testing/selftests/mm/pagemap_ioctl.c b/tools/testing/selftests/mm/pagemap_ioctl.c
> index eadc7159ca5b..48cbea3a33c9 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, int vec_len, int flag,
>  			  int max_pages, long required_mask, long anyof_mask, long excluded_mask,
>  			  long return_mask)
>  {
> @@ -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,
> @@ -787,7 +787,7 @@ 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;
> -- 
> 2.53.0
>