Re: [RFC PATCH v5 01/15] mm: Consolidate freeing of typed folios on final folio_put()

[Vlastimil Babka <vbabka@suse.cz>]

On 1/20/25 11:43, Vlastimil Babka wrote:
> On 1/20/25 11:39, David Hildenbrand wrote:
>> On 17.01.25 17:29, Fuad Tabba wrote:
>>> diff --git a/mm/swap.c b/mm/swap.c
>>> index 10decd9dffa1..6f01b56bce13 100644
>>> --- a/mm/swap.c
>>> +++ b/mm/swap.c
>>> @@ -94,6 +94,20 @@ static void page_cache_release(struct folio *folio)
>>>   		unlock_page_lruvec_irqrestore(lruvec, flags);
>>>   }
>>>   
>>> +static void free_typed_folio(struct folio *folio)
>>> +{
>>> +	switch (folio_get_type(folio)) {
>>> +	case PGTY_hugetlb:
>>> +		free_huge_folio(folio);
>>> +		return;
>>> +	case PGTY_offline:
>>> +		/* Nothing to do, it's offline. */
>>> +		return;
>> 
>> Please drop the PGTY_offline part for now, it was rather to highlight 
>> what could be done.
>> 
>> But the real goal will be to not make offline pages
>> use the refcount at all (frozen).
>> 
>> If we really want the temporary PGTY_offline change, it should be 
>> introduced separately.
>> 
>> Apart from that LGTM!
> 
> I gues you mean the WARN_ON_ONCE(1) should be dropped from the default:
> handler as well, right? IIUC offline pages are not not yet frozen so there
> will be warnings otherwise. And I haven't check if the other types are
> frozen (I know slab is, very recently :)

Oh and also free_typed_folio() would have to become bool and if it returns
false, the normal freeing proceeds?