Re: [PATCH v2 5/7] mm: thp: split huge page to any lower order pages.

[David Hildenbrand]

On 29.03.23 03:17, Zi Yan wrote:
> From: Zi Yan <ziy@xxxxxxxxxx>
>
> To split a THP to any lower order pages, we need to reform THPs on
> subpages at given order and add page refcount based on the new page
> order. Also we need to reinitialize page_deferred_list after removing
> the page from the split_queue, otherwise a subsequent split will see
> list corruption when checking the page_deferred_list again.
>
> It has many uses, like minimizing the number of pages after
> truncating a huge pagecache page. For anonymous THPs, we can only split
> them to order-0 like before until we add support for any size anonymous
> THPs.

Because I'm currently looking into something that would also not be 
compatible with order-1 for now:

You should make it clear that order-1 is not supported, like:

"mm: thp: split huge page to any lower order pages (except order 1)"

And clarify in the subject why that is the case.

--
Cheers,

David / dhildenb