Re: [PATCH] mm/hugetlb: Fix build failure with HUGETLB_PAGE but not HUGEBTLBFS

From: Mike Kravetz
Date: Tue Mar 17 2020 - 12:40:51 EST


On 3/17/20 1:43 AM, Christophe Leroy wrote:
>
>
> Le 17/03/2020 Ã 09:25, Baoquan He a Ãcrit :
>> On 03/17/20 at 08:04am, Christophe Leroy wrote:
>>> When CONFIG_HUGETLB_PAGE is set but not CONFIG_HUGETLBFS, the
>>> following build failure is encoutered:
>>
>> From the definition of HUGETLB_PAGE, isn't it relying on HUGETLBFS?
>> I could misunderstand the def_bool, please correct me if I am wrong.
>
> AFAIU, it means that HUGETLBFS rely on HUGETLB_PAGE, by default HUGETLB_PAGE is not selected when HUGETLBFS is not. But it is still possible for an arch to select HUGETLB_PAGE without selecting HUGETLBFS when it uses huge pages for other purpose than hugetlb file system.
>

Hi Christophe,

Do you actually have a use case/example of using hugetlb pages without
hugetlbfs? I can understand that there are some use cases which never
use the filesystem interface. However, hugetlb support is so intertwined
with hugetlbfs, I am thinking there would be issues trying to use them
separately. I will look into this further.

--
Mike Kravetz