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

Le 17/03/2020 à 17:40, Mike Kravetz a écrit :

On 3/17/20 1:43 AM, Christophe Leroy wrote:

quoted

Le 17/03/2020 à 09:25, Baoquan He a écrit :

quoted

On 03/17/20 at 08:04am, Christophe Leroy wrote:

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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.

Hi Mike,

Series https://patchwork.ozlabs.org/project/linuxppc-dev/list/?series=164620

And especially patch 39 to 41.

Thanks
Christophe