Re: [PATCH v3 05/18] mm/huge_memory: rename __split_unmapped_folio() to __split_frozen_folio()

[David Hildenbrand (Arm)]

On 8/27/26 17:06, Kiryl Shutsemau wrote:
> On Fri, Aug 21, 2026 at 02:55:18AM +0800, Kairui Song via B4 Relay wrote:
>> From: Kairui Song <kasong@xxxxxxxxxxx>
>>
>> The helper splits a folio whose refcount is frozen: the frozen refcount
>> is the state it relies on, while unmapping is arranged by the caller
>> beforehand. The old name caused confusion and people may try to call the
>> helper on non-frozen folios.
>>
>> Suggested-by: Zi Yan <ziy@xxxxxxxxxx>
>> Reviewed-by: Zi Yan <ziy@xxxxxxxxxx>
>> Signed-off-by: Kairui Song <kasong@xxxxxxxxxxx>
> 
> This patch is fine:
> 
> Reviewed-by: Kiryl Shutsemau (Meta) <kas@xxxxxxxxxx>
> 
>> @@ -3989,8 +3989,8 @@ static int __folio_freeze_split_unmapped_anon(struct folio *folio, unsigned int
>>  	if (do_lru)
>>  		lruvec = folio_lruvec_lock(folio);
>>  
>> -	ret = __split_unmapped_folio(folio, new_order, split_at, NULL,
>> -				     NULL, split_type);
>> +	ret = __split_frozen_folio(folio, new_order, split_at, NULL,
>> +				   NULL, split_type);
>>  
>>  	/*
>>  	 * Unfreeze the post-split folios and put them back to the right
>> @@ -4053,8 +4053,8 @@ static int __folio_freeze_split_unmapped_file(struct folio *folio, unsigned int
>>  	if (do_lru)
>>  		lruvec = folio_lruvec_lock(folio);
>>  
>> -	ret = __split_unmapped_folio(folio, new_order, split_at, xas,
>> -				     mapping, split_type);
>> +	ret = __split_frozen_folio(folio, new_order, split_at, xas,
>> +				   mapping, split_type);
>>  
>>  	/*
>>  	 * Unfreeze after-split folios and put them back to the right
> 
> But now you have *unmapped_anon/file() call *frozen_folio().
> 
> Given that you introduced *unmapped_anon/file() in the previous patch,
> why not give them the right names from the start?
> 

+1

And just for completeness:  we cannot possibly freeze a mapped folio. So frozen
implies unmapped.

So the function can possibly just be called

	__folio_freeze_split_file

And we can can add a

	VM_WARN_ON_ONCE(folio_mapped(folio));

to self-document the expectation in the code.

-- 
Cheers,

David