Re: [RFC PATCH 1/3] mm: move folio split code into mm/folio_split.c

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 3 potential
issues to consider:
- [Medium] mm: missing linux/page_idle.h include in mm/folio_split.c
  breaks 32-bit build
- [Low] mm: missing mm/folio_split.c kernel-doc in
  Documentation/core-api/mm-api.rst
- [Low] mm: commit message misidentifies caller of
  folio_reset_partially_mapped()
--

commit 6a62de8a2d72809396114752978350fdd94905
Author: Fang Xieyan <fangxy@xiaopeng.com>

mm: move folio split code into mm/folio_split.c

This commit moves the folio split implementation out of mm/huge_memory.c into
mm/folio_split.c and exposes folio_reset_partially_mapped() in mm/internal.h.

>  - folio_reset_partially_mapped() is no longer static and gains a
>    declaration in mm/internal.h, because deferred_split_scan() in
>    huge_memory.c keeps calling it,

[Severity: Low]
In mm/huge_memory.c, __folio_unqueue_deferred_split() is the caller of
folio_reset_partially_mapped(), not deferred_split_scan().

> diff --git a/mm/folio_split.c b/mm/folio_split.c
> new file mode 100644
> index 0000000000000..7770d8215a076
> --- /dev/null
> +++ b/mm/folio_split.c
> @@ -0,0 +1,947 @@
[ ... ]
> +#include <linux/page_owner.h>
> +#include <linux/pgalloc_tag.h>
> +#include <linux/vmstat.h>
> +
> +#include "internal.h"
> +#include "swap.h"
[ ... ]
> +static void __split_folio_to_order(struct folio *folio, int old_order,
> +		int new_order)
> +{
[ ... ]
> +		if (folio_test_young(folio))
> +			folio_set_young(new_folio);
> +		if (folio_test_idle(folio))
> +			folio_set_idle(new_folio);

[Severity: Medium]
Does mm/folio_split.c need to include <linux/page_idle.h> (and drop it from
mm/huge_memory.c)?

When CONFIG_PAGE_IDLE_FLAG=y and !CONFIG_64BIT, include/linux/page-flags.h
omits folio_test_young(), folio_set_young(), folio_test_idle() and
folio_set_idle(), and defines them in include/linux/page_idle.h instead, so
32-bit builds with CONFIG_PAGE_IDLE_FLAG=y fail with implicit declaration
errors here.

[ ... ]

> +/**
> + * folio_split() - split a folio at @split_at to a @new_order folio
> + * @folio: folio to split
> + * @new_order: the order of the new folio
> + * @split_at: a page within the new folio
> + * @list: after-split folios are added to @list if not null, otherwise to LRU
> + *        list

[Severity: Low]
Documentation/core-api/mm-api.rst includes .. kernel-doc:: mm/huge_memory.c
without function filters.  Should .. kernel-doc:: mm/folio_split.c be added
there as well so the six moved kernel-doc comments (__split_frozen_folio(),
folio_check_splittable(), __folio_split(), folio_split_unmapped(),
folio_split() and min_order_for_split()) are not dropped from the generated
documentation?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261110035205.3036-1-fangxy@xiaopeng.com?part=1