Re: [PATCH v4 6/6] mm: hugetlb: allocate frozen pages in alloc_gigantic_folio()

[Zi Yan <ziy@nvidia.com>]

On 17 Dec 2025, at 3:09, Kefeng Wang wrote:

> On 2025/12/17 2:44, Zi Yan wrote:
>> On 16 Dec 2025, at 6:48, Kefeng Wang wrote:
>>
>>> The alloc_gigantic_folio() allocates a folio with refcount increated
>>> and then freeze it, convert to allocate a frozen folio to remove the
>>> atomic operation about folio refcount, and saving atomic operation
>>> during __update_and_free_hugetlb_folio() too.
>>>
>>> Besides, rename hugetlb_cma_{alloc,free}_folio() with frozen which
>>> make them more self-explanatory.
>>>
>>> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
>>> ---
>>>   mm/hugetlb.c     | 63 +++++++++++-------------------------------------
>>>   mm/hugetlb_cma.c |  9 +++----
>>>   mm/hugetlb_cma.h | 10 ++++----
>>>   3 files changed, 22 insertions(+), 60 deletions(-)
>>>
>>> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
>>> index ed185bbca419..7779ec838da0 100644
>>> --- a/mm/hugetlb.c
>>> +++ b/mm/hugetlb.c
>>> @@ -121,16 +121,6 @@ static void hugetlb_unshare_pmds(struct vm_area_struct *vma,
>>>   		unsigned long start, unsigned long end, bool take_locks);
>>>   static struct resv_map *vma_resv_map(struct vm_area_struct *vma);
>>>
>>> -static void hugetlb_free_folio(struct folio *folio)
>>> -{
>>> -	if (folio_test_hugetlb_cma(folio)) {
>>> -		hugetlb_cma_free_folio(folio);
>>> -		return;
>>> -	}
>>> -
>>> -	folio_put(folio);
>>> -}
>>> -
>>>   static inline bool subpool_is_free(struct hugepage_subpool *spool)
>>>   {
>>>   	if (spool->count)
>>> @@ -1417,51 +1407,24 @@ static struct folio *dequeue_hugetlb_folio_vma(struct hstate *h,
>>>   	return NULL;
>>>   }
>>>
>>> -#ifdef CONFIG_ARCH_HAS_GIGANTIC_PAGE
>>> -#ifdef CONFIG_CONTIG_ALLOC
>>> +#if defined(CONFIG_ARCH_HAS_GIGANTIC_PAGE) && defined(CONFIG_CONTIG_ALLOC)
>>>   static struct folio *alloc_gigantic_folio(int order, gfp_t gfp_mask,
>>>   		int nid, nodemask_t *nodemask)
>>>   {
>>>   	struct folio *folio;
>>> -	bool retried = false;
>>>
>>> -retry:
>>> -	folio = hugetlb_cma_alloc_folio(order, gfp_mask, nid, nodemask);
>>> -	if (!folio) {
>>> -		struct page *page;
>>> -
>>> -		if (hugetlb_cma_exclusive_alloc())
>>> -			return NULL;
>>> -
>>> -		page = alloc_contig_frozen_pages(1 << order, gfp_mask, nid, nodemask);
>>> -		if (!page)
>>> -			return NULL;
>>> -
>>> -		set_page_refcounted(page);
>>> -		folio = page_folio(page);
>>> -	}
>>> -
>>> -	if (folio_ref_freeze(folio, 1))
>>> +	folio = hugetlb_cma_alloc_frozen_folio(order, gfp_mask, nid, nodemask);
>>> +	if (folio)
>>>   		return folio;
>>
>> alloc_gigantic_folio() actually returns a frozen folio. Should it be renamed
>> to alloc_frozen_gigantic_folio()?
>
> I don't change it as alloc_buddy_hugetlb_folio is not with frozen, we could change both of them if you prefer with frozen :)

Better to change both for clearer function names. Thanks.

Best Regards,
Yan, Zi