RE: [PATCH] tools/mm/thp_swap_allocator_test: Fix small folio alignment

["Kumar, Kaushlendra" <kaushlendra.kumar@intel.com>]

On Tue, 9 Dec 2025, Andrew Morton wrote:
> On Tue,  9 Dec 2025 08:47:45 +0530 Kaushlendra Kumar wrote:
>> Use ALIGNMENT_SMALLFOLIO instead of ALIGNMENT_MTHP when allocating 
>> small folios to ensure correct memory alignment for the test case.
>> 
>> ...
>>
>> --- a/tools/mm/thp_swap_allocator_test.c
>> +++ b/tools/mm/thp_swap_allocator_test.c
>> @@ -142,7 +142,7 @@ int main(int argc, char *argv[])
>>  	}
>>  
>>  	if (use_small_folio) {
>> -		mem2 = aligned_alloc_mem(MEMSIZE_SMALLFOLIO, ALIGNMENT_MTHP);
>> +		mem2 = aligned_alloc_mem(MEMSIZE_SMALLFOLIO, ALIGNMENT_SMALLFOLIO);
>>  		if (mem2 == NULL) {
>>  			fprintf(stderr, "Failed to allocate small folios memory\n");
>>  			free(mem1);
>
> What are the worst-case userspace visible runtime effects of this change?

Before: test allocates small folios with 64KB alignment (ALIGNMENT_MTHP) when 
only 4KB alignment (ALIGNMENT_SMALLFOLIO) is needed. This wastes address space 
and may cause allocation failures on systems with fragmented memory.
Worst-case impact: this only affects thp_swap_allocator_test tool behavior.

-Kaushlendra