Re: [PATCH 4/5] mm: hugetlb: avoid recursive CMA allocation during migration

["Qi Zheng" <zhengqi.arch@bytedance.com>]

On 10/18/26 2:54 AM, Jose A. Perez de Azpillaga wrote:
> On 10/16/26 12:07 PM, Qi Zheng wrote:
>> From: Qi Zheng <zhengqi.arch@bytedance.com>
>>
>> Contiguous allocation can migrate allocated HugeTLB folios or replace free
>> HugeTLB folios while holding a CMA allocation mutex. Allocating a
>> replacement through CMA would recurse into that allocation path once
>> non-gigantic HugeTLB pages can use CMA.
>>
>> Add a fresh allocation helper that bypasses CMA, and use it for free folio
>> replacement. Pass an explicit allow_cma argument through the migration
>> allocation API and disable it for MR_CONTIG_RANGE. Honor hugetlb_cma_only
>> by failing fresh allocation when the corresponding size requires CMA.
>>
>> The existing gigantic migration restriction is unchanged.
>>
>> Assisted-by: LLM
>> Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
> 
> [snip]
> 
>>   /*
>> - * Common helper to allocate a fresh hugetlb folio. All specific allocators
>> - * should use this function to get new hugetlb folio
>> + * Common helper to allocate a fresh hugetlb folio.
> 
> couldn't allow_cma be passed down to alloc_fresh_hugetlb_folio() instead
> of adding a second copy of it, so this line can stay?

make sense, will do.

Thanks,
Qi