Re: [PATCH 2/2] selftests/mm: add tests for splitting pmd THPs to all lower orders.

[Zi Yan]

On 15 Jan 2025, at 21:52, Zi Yan wrote:

> On 10 Jan 2025, at 18:50, Zi Yan wrote:
>
>> Kernel already supports splitting a folio to any lower order. Test it.
>>
>> Signed-off-by: Zi Yan <ziy@xxxxxxxxxx>
>> ---
>>  tools/testing/selftests/mm/split_huge_page_test.c | 13 ++++++++-----
>>  1 file changed, 8 insertions(+), 5 deletions(-)
>>
>> diff --git a/tools/testing/selftests/mm/split_huge_page_test.c b/tools/testing/selftests/mm/split_huge_page_test.c
>> index 128004308233..3d3bc40a268b 100644
>> --- a/tools/testing/selftests/mm/split_huge_page_test.c
>> +++ b/tools/testing/selftests/mm/split_huge_page_test.c
>> @@ -144,7 +144,7 @@ void split_pmd_zero_pages(void)
>>  	free(one_page);
>>  }
>>
>> -void split_pmd_thp(void)
>> +void split_pmd_thp_to_order(int order)
>>  {
>>  	char *one_page;
>>  	size_t len = 4 * pmd_pagesize;
>> @@ -164,7 +164,7 @@ void split_pmd_thp(void)
>>
>>  	/* split all THPs */
>>  	write_debugfs(PID_FMT, getpid(), (uint64_t)one_page,
>> -		(uint64_t)one_page + len, 0);
>> +		(uint64_t)one_page + len, order);
>>
>>  	for (i = 0; i < len; i++)
>>  		if (one_page[i] != (char)i)
>> @@ -174,7 +174,7 @@ void split_pmd_thp(void)
>>  	if (!check_huge_anon(one_page, 0, pmd_pagesize))
>>  		ksft_exit_fail_msg("Still AnonHugePages not split\n");
>>
>> -	ksft_test_result_pass("Split huge pages successful\n");
>> +	ksft_test_result_pass("Split huge pages to order %d successful\n", order);
>>  	free(one_page);
>>  }
>>
>> @@ -481,7 +481,7 @@ int main(int argc, char **argv)
>>  	if (argc > 1)
>>  		optional_xfs_path = argv[1];
>>
>> -	ksft_set_plan(4+9);
>> +	ksft_set_plan(1+9+2+9);
>>
>>  	pagesize = getpagesize();
>>  	pageshift = ffs(pagesize) - 1;
>> @@ -492,7 +492,10 @@ int main(int argc, char **argv)
>>  	fd_size = 2 * pmd_pagesize;
>>
>>  	split_pmd_zero_pages();
>> -	split_pmd_thp();
>> +
>> +	for (i = 0; i < 9; i++)
>> +		split_pmd_thp_to_order(i);
>> +
>>  	split_pte_mapped_thp();
>>  	split_file_backed_thp();
>>
>
> Hi Andrew,
>
> Can you fold the patch below into this one? Anonymous memory does not
> support order-1 folio, so there is no need to test splitting to order-1.
> Kernel will WARN_ONCE for split_pmd_thp_to_order(1) test and the whole
> test will fail at that point.

Please use the one below, since the number of total tests should be adjusted
as well. Sorry about the noise.


diff --git a/tools/testing/selftests/mm/split_huge_page_test.c b/tools/testing/selftests/mm/split_huge_page_test.c
index 3d3bc40a268b..dedab4059c4c 100644
--- a/tools/testing/selftests/mm/split_huge_page_test.c
+++ b/tools/testing/selftests/mm/split_huge_page_test.c
@@ -481,7 +481,7 @@ int main(int argc, char **argv)
 	if (argc > 1)
 		optional_xfs_path = argv[1];

-	ksft_set_plan(1+9+2+9);
+	ksft_set_plan(1+8+2+9);

 	pagesize = getpagesize();
 	pageshift = ffs(pagesize) - 1;
@@ -494,7 +494,8 @@ int main(int argc, char **argv)
 	split_pmd_zero_pages();

 	for (i = 0; i < 9; i++)
-		split_pmd_thp_to_order(i);
+		if (i != 1)
+			split_pmd_thp_to_order(i);

 	split_pte_mapped_thp();
 	split_file_backed_thp();



--
Best Regards,
Yan, Zi