Re: [PATCH v5 09/14] mm/truncate: use folio_split() in truncate_inode_partial_folio()

[David Hildenbrand (Arm)]

On 4/29/26 17:35, Zi Yan wrote:
> After READ_ONLY_THP_FOR_FS is removed, FS either supports large folio or
> not. folio_split() can be used on a FS with large folio support without
> worrying about getting a THP on a FS without large folio support.
> 
> When READ_ONLY_THP_FOR_FS was present, a PMD large pagecache folio can
> appear in a FS without large folio support after khugepaged or
> madvise(MADV_COLLAPSE) creates it. During truncate_inode_partial_folio(),
> such a PMD large pagecache folio is split and if the FS does not support
> large folio, it needs to be split to order-0 ones and could not be split
> non uniformly to ones with various orders. try_folio_split_to_order() was
> added to handle this situation by checking folio_check_splittable(...,
> SPLIT_TYPE_NON_UNIFORM) to detect if the large folio is created due to
> READ_ONLY_THP_FOR_FS and the FS does not support large folio. Now
> READ_ONLY_THP_FOR_FS is removed, all large pagecache folios are created
> with FSes supporting large folio, this function is no longer needed and all
> large pagecache folios can be split non uniformly.
> 
> Signed-off-by: Zi Yan <ziy@xxxxxxxxxx>
> ---

Acked-by: David Hildenbrand (Arm) <david@xxxxxxxxxx>

-- 
Cheers,

David