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

[Kefeng Wang <wangkefeng.wang@huawei.com>]

On 2025/12/18 3:40, Zi Yan wrote:
> 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.

Sure, I will change both alloc_buddy_hugetlb_folio and alloc_gigantic_folio.

> 
> Best Regards,
> Yan, Zi
>