Re: [PATCH] huge_memory: return -EINVAL in folio split functions when THP is disabled

[David Hildenbrand]

On 02.09.25 10:40, Pankaj Raghav (Samsung) wrote:
> From: Pankaj Raghav <p.raghav@xxxxxxxxxxx>
>
> split_huge_page_to_list_[to_order](), split_huge_page() and
> try_folio_split() return 0 on success and error codes on failure.
>
> When THP is disabled, these functions return 0 indicating success even
> though an error code should be returned as it is not possible to split a
> folio when THP is disabled.
>
> Make all these functions return -EINVAL to indicate failure instead of
> 0.
>
> This issue was discovered while experimenting enabling large folios
> without THP and found that returning 0 in these functions is resulting in
> undefined behavior in truncate operations. This change fixes the issue.

Currently large folios that could be split are impossible without THP, 
so why should this be a fix?

--
Cheers

David / dhildenb