On 2016/8/22 18:00, Catalin Marinas wrote:

On Mon, Aug 22, 2016 at 10:03:58AM +0200, Michal Hocko wrote:

quoted

On Mon 22-08-16 10:56:43, Xie Yisheng wrote:

quoted

Arm64 supports gigantic page after
commit 084bd29810a5 ("ARM64: mm: HugeTLB support.")
however, it got broken by 
commit 944d9fec8d7a ("hugetlb: add support for gigantic page
allocation at runtime")

This patch selects ARCH_HAS_GIGANTIC_PAGE to make this
function can be used again.

I haven't double checked that the above commit really broke it but if
that is the case then
 
Fixes: 944d9fec8d7a ("hugetlb: add support for gigantic page allocation at runtime")

would be nice as well I guess. I do not think that marking it for stable
is really necessary considering how long it's been broken and nobody has
noticed...

I'm not sure that commit broke it. The gigantic functionality introduced
by the above commit was under an #ifdef CONFIG_X86_64. Prior
to that we had a VM_BUG_ON(hstate_is_gigantic(h)).

Hi Catalin and Michal ,
Thank you for your reply.
Before that commit gigantic pages can only be allocated at boottime and
can't be freed. That why we had VM_BUG_ON(hstate_is_gigantic(h)) in
function update_and_free_page() Prior to that.

Anyway, it should not just add #ifdef CONFIG_X86_64 for arm64 already
supported 1G hugepage before that commit. Right?

Please let me know if I miss something.

Thanks
Xie Yisheng.