Re: [PATCH v4 2/3] mm: gup: allow long-term pins of CMA-allocated HugeTLB folios

[Qi Zheng <qi.zheng@linux.dev>]

On 11/11/26 3:42 PM, Muchun Song wrote:
> 
> 
>> On Nov 11, 2026, at 14:46, Qi Zheng <qi.zheng@linux.dev> wrote:
>>
>> From: Qi Zheng <zhengqi.arch@bytedance.com>
>>
>> Long-term pinning treats explicitly CMA-allocated HugeTLB folios as
>> unpinnable, causing unnecessary migration or pinning failures.
>>
>> These folios already own their CMA bitmap ranges, and memory blocks
> 
> Commit message needs updating to bitmap as well.

Will do.

> 
>> overlapping CMA areas cannot be offlined. Allow HugeTLB folios with
>> HPG_cma to be pinned directly, including in ZONE_MOVABLE.
>>
>> Fixes: cf11e85fc08c ("mm: hugetlb: optionally allocate gigantic hugepages using cma")
>> Cc: stable@vger.kernel.org
>> Suggested-by: Muchun Song <muchun.song@linux.dev>
>> Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
>> Acked-by: Muchun Song <muchun.song@linux.dev>
>> Reviewed-by: Oscar Salvador <osalvador@suse.de>
>> Reviewed-by: Jose A. Perez de Azpillaga <azpijr@gmail.com>
>> ---
>> include/linux/mm.h | 29 +----------------------------
>> mm/gup.c           | 31 +++++++++++++++++++++++++++++++
>> 2 files changed, 32 insertions(+), 28 deletions(-)
>>
>> diff --git a/include/linux/mm.h b/include/linux/mm.h
>> index b0da9be413098..47d1d96bfc7fd 100644
>> --- a/include/linux/mm.h
>> +++ b/include/linux/mm.h
>> @@ -2954,35 +2954,8 @@ static inline bool is_zero_folio(const struct folio *folio)
>> 	return is_zero_page(&folio->page);
>> }
>>
>> -/* MIGRATE_CMA and ZONE_MOVABLE do not allow pin folios */
>> #ifdef CONFIG_MIGRATION
>> -static inline bool folio_is_longterm_pinnable(struct folio *folio)
> 
> I think David prefer to move this function first, then fix it in a separate patch,
> right?

Hi David, is this what you mean? If so, I will split it into two patches
for the v5.

Thanks,
Qi