Re: [PATCH v3 02/54] selftests/mm: migration: don't assume hupe page is TWOMEG

[Luiz Capitulino <luizcap@redhat.com>]

On 2026-04-28 16:41, Mike Rapoport wrote:
> From: "Mike Rapoport (Microsoft)" <rppt@kernel.org>
> 
> migration tests presume that both THP and HugeTLB huge pages are 2MB.
> 
> Add dynamic detection of huge page size with read_pmd_pagesize() for THP
> and with default_huge_page_size() for HugeTLB.
> 
> Reviewed-by: Donet Tom <donettom@linux.ibm.com>
> Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
> ---
>   tools/testing/selftests/mm/migration.c | 44 +++++++++++++++++++-------
>   1 file changed, 32 insertions(+), 12 deletions(-)
> 
> diff --git a/tools/testing/selftests/mm/migration.c b/tools/testing/selftests/mm/migration.c
> index 60e78bbfc0e3..7e547d945e1a 100644
> --- a/tools/testing/selftests/mm/migration.c
> +++ b/tools/testing/selftests/mm/migration.c
> @@ -184,22 +184,27 @@ TEST_F_TIMEOUT(migration, shared_anon, 2*RUNTIME)
>    */
>   TEST_F_TIMEOUT(migration, private_anon_thp, 2*RUNTIME)
>   {
> +	uint64_t pmdsize;
>   	uint64_t *ptr;
>   	int i;
>   
>   	if (!thp_is_enabled())
>   		SKIP(return, "Transparent Hugepages not available");
>   
> +	pmdsize = read_pmd_pagesize();
> +	if (!pmdsize)
> +		SKIP(return, "Reading PMD pagesize failed");
> +
>   	if (self->nthreads < 2 || self->n1 < 0 || self->n2 < 0)
>   		SKIP(return, "Not enough threads or NUMA nodes available");
>   
> -	ptr = mmap(NULL, 2*TWOMEG, PROT_READ | PROT_WRITE,
> +	ptr = mmap(NULL, 2 * pmdsize, PROT_READ | PROT_WRITE,
>   		MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
>   	ASSERT_NE(ptr, MAP_FAILED);
>   
> -	ptr = (uint64_t *) ALIGN((uintptr_t) ptr, TWOMEG);
> -	ASSERT_EQ(madvise(ptr, TWOMEG, MADV_HUGEPAGE), 0);
> -	memset(ptr, 0xde, TWOMEG);
> +	ptr = (uint64_t *) ALIGN((uintptr_t) ptr, pmdsize);
> +	ASSERT_EQ(madvise(ptr, pmdsize, MADV_HUGEPAGE), 0);
> +	memset(ptr, 0xde, pmdsize);
>   	for (i = 0; i < self->nthreads - 1; i++)
>   		if (pthread_create(&self->threads[i], NULL, access_mem, ptr))
>   			perror("Couldn't create thread");
> @@ -215,6 +220,7 @@ TEST_F_TIMEOUT(migration, private_anon_thp, 2*RUNTIME)
>   
>   TEST_F_TIMEOUT(migration, shared_anon_thp, 2*RUNTIME)
>   {
> +	unsigned long pmdsize;

I don't remember if this is the one I caught before, but would be good
to match read_pmd_pagesize() uint64_t type.

As this is minor:

Reviewed-by: Luiz Capitulino <luizcap@redhat.com>

>   	pid_t pid;
>   	uint64_t *ptr;
>   	int i;
> @@ -222,17 +228,21 @@ TEST_F_TIMEOUT(migration, shared_anon_thp, 2*RUNTIME)
>   	if (!thp_is_enabled())
>   		SKIP(return, "Transparent Hugepages not available");
>   
> +	pmdsize = read_pmd_pagesize();
> +	if (!pmdsize)
> +		SKIP(return, "Reading PMD pagesize failed");
> +
>   	if (self->nthreads < 2 || self->n1 < 0 || self->n2 < 0)
>   		SKIP(return, "Not enough threads or NUMA nodes available");
>   
> -	ptr = mmap(NULL, 2 * TWOMEG, PROT_READ | PROT_WRITE,
> +	ptr = mmap(NULL, 2 * pmdsize, PROT_READ | PROT_WRITE,
>   		MAP_SHARED | MAP_ANONYMOUS, -1, 0);
>   	ASSERT_NE(ptr, MAP_FAILED);
>   
> -	ptr = (uint64_t *) ALIGN((uintptr_t) ptr, TWOMEG);
> -	ASSERT_EQ(madvise(ptr, TWOMEG, MADV_HUGEPAGE), 0);
> +	ptr = (uint64_t *) ALIGN((uintptr_t) ptr, pmdsize);
> +	ASSERT_EQ(madvise(ptr, pmdsize, MADV_HUGEPAGE), 0);
>   
> -	memset(ptr, 0xde, TWOMEG);
> +	memset(ptr, 0xde, pmdsize);
>   	for (i = 0; i < self->nthreads - 1; i++) {
>   		pid = fork();
>   		if (!pid) {
> @@ -256,17 +266,22 @@ TEST_F_TIMEOUT(migration, shared_anon_thp, 2*RUNTIME)
>    */
>   TEST_F_TIMEOUT(migration, private_anon_htlb, 2*RUNTIME)
>   {
> +	unsigned long hugepage_size;
>   	uint64_t *ptr;
>   	int i;
>   
>   	if (self->nthreads < 2 || self->n1 < 0 || self->n2 < 0)
>   		SKIP(return, "Not enough threads or NUMA nodes available");
>   
> -	ptr = mmap(NULL, TWOMEG, PROT_READ | PROT_WRITE,
> +	hugepage_size = default_huge_page_size();
> +	if (!hugepage_size)
> +		SKIP(return, "Reading HugeTLB pagesize failed\n");
> +
> +	ptr = mmap(NULL, hugepage_size, PROT_READ | PROT_WRITE,
>   		MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB, -1, 0);
>   	ASSERT_NE(ptr, MAP_FAILED);
>   
> -	memset(ptr, 0xde, TWOMEG);
> +	memset(ptr, 0xde, hugepage_size);
>   	for (i = 0; i < self->nthreads - 1; i++)
>   		if (pthread_create(&self->threads[i], NULL, access_mem, ptr))
>   			perror("Couldn't create thread");
> @@ -281,6 +296,7 @@ TEST_F_TIMEOUT(migration, private_anon_htlb, 2*RUNTIME)
>    */
>   TEST_F_TIMEOUT(migration, shared_anon_htlb, 2*RUNTIME)
>   {
> +	unsigned long hugepage_size;
>   	pid_t pid;
>   	uint64_t *ptr;
>   	int i;
> @@ -288,11 +304,15 @@ TEST_F_TIMEOUT(migration, shared_anon_htlb, 2*RUNTIME)
>   	if (self->nthreads < 2 || self->n1 < 0 || self->n2 < 0)
>   		SKIP(return, "Not enough threads or NUMA nodes available");
>   
> -	ptr = mmap(NULL, TWOMEG, PROT_READ | PROT_WRITE,
> +	hugepage_size = default_huge_page_size();
> +	if (!hugepage_size)
> +		SKIP(return, "Reading HugeTLB pagesize failed\n");
> +
> +	ptr = mmap(NULL, hugepage_size, PROT_READ | PROT_WRITE,
>   		MAP_SHARED | MAP_ANONYMOUS | MAP_HUGETLB, -1, 0);
>   	ASSERT_NE(ptr, MAP_FAILED);
>   
> -	memset(ptr, 0xde, TWOMEG);
> +	memset(ptr, 0xde, hugepage_size);
>   	for (i = 0; i < self->nthreads - 1; i++) {
>   		pid = fork();
>   		if (!pid) {