Re: [PATCH 1/2] mm: Make alloc_contig_range handle free hugetlb pages

[Oscar Salvador]

On 2021-02-18 14:59, Michal Hocko wrote:
> As I've said. Page allocator can cope with NULL nodemask just fine.
> I have checked the code and now remember the tricky part. It is
> alloc_gigantic_page which cannot work with NULL nodemask because it
> relies on for_each_node_mask and that, unlike zonelist iterator, cannot
> cope with NULL node mask. This is the case only for !GFP_THISNODE.

Ok, thanks for the clarification.

> OK, I see the problem now. And your above solution is not really
> optimal either. Your put_page would add the page to the pool and so it
> could be used by somebody. One

Yeah, that is right.

> way around it would be either directly
> manipulating reference count which is fugly or you can make it a
> temporal page (alloc_migrate_huge_page) or maybe even better not 
> special
> case this here but rather allow migrating free hugetlb pages in the
> migrate_page path.

I will have a look into it to see how what would look.

Thanks for the feedback

--
Oscar Salvador
SUSE L3