Re: [PATCH v4 05/11] mm: do not split a folio if it has minimum folio order requirement

Matthew Wilcox
2024-04-25T20:10:23Z

On Thu, Apr 25, 2024 at 01:37:40PM +0200, Pankaj Raghav (Samsung) wrote:
> From: Pankaj Raghav <p.raghav@samsung.com>
>
> Splitting a larger folio with a base order is supported using
> split_huge_page_to_list_to_order() API. However, using that API for LBS
> is resulting in an NULL ptr dereference error in the writeback path [1].
>
> Refuse to split a folio if it has minimum folio order requirement until
> we can start using split_huge_page_to_list_to_order() API. Splitting the
> folio can be added as a later optimization.
>
> [1] https://gist.github.com/mcgrof/d12f586ec6ebe32b2472b5d634c397df

Obviously this has to be tracked down and fixed before this patchset can
be merged ... I think I have some ideas. Let me look a bit. How
would I go about reproducing this?