Re: [PATCH 06/21] mm/pgtable: define (pgd|p4d|pud)_leaf() for folded page tables

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] mm: broken macro definitions for p4d_ERROR and pud_ERROR
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commit b1d94b4085bf94fbd22f26d0b8cf668f45ded666
Author: David Hildenbrand (Arm) <david@kernel.org>

mm/pgtable: define (pgd|p4d|pud)_leaf() for folded page tables

This commit defines pgd_leaf(), p4d_leaf(), and pud_leaf() for folded page
tables, hard-coding them to return false. It updates the functions to use bool
as a return type and ensures pud_leaf() is defined to prevent architectures from
inadvertently overwriting it.

> diff --git a/include/asm-generic/pgtable-nop4d.h b/include/asm-generic/pgtable-nop4d.h
> index 1cf739ee38aa1..c6a5a43899b50 100644
> --- a/include/asm-generic/pgtable-nop4d.h
> +++ b/include/asm-generic/pgtable-nop4d.h
> @@ -22,6 +22,9 @@ static inline int pgd_none(pgd_t pgd)		{ return 0; }
>  static inline int pgd_bad(pgd_t pgd)		{ return 0; }
>  static inline int pgd_present(pgd_t pgd)	{ return 1; }
>  static inline void pgd_clear(pgd_t *pgd)	{ }
> +static inline bool pgd_leaf(pgd_t pgd)		{ return false; }
> +#define pgd_leaf pgd_leaf
> +#define p4d_ERROR(p4d)				(pgd_ERROR((p4d).pgd))

[Severity: Low]
Is this p4d_ERROR() macro definition correct? It expands to pgd_ERROR(), but
pgd_ERROR() does not appear to exist in the kernel. This could cause a compile
error if a developer attempts to use p4d_ERROR() in architectures relying on
include/asm-generic/pgtable-nop4d.h.

>  
>  #define pgd_populate(mm, pgd, p4d)		do { } while (0)
>  #define pgd_populate_safe(mm, pgd, p4d)		do { } while (0)

[ ... ]

> diff --git a/include/asm-generic/pgtable-nopud.h b/include/asm-generic/pgtable-nopud.h
> index eedee8e3ad68f..6c9bca78047c4 100644
> --- a/include/asm-generic/pgtable-nopud.h
> +++ b/include/asm-generic/pgtable-nopud.h
> @@ -29,6 +29,9 @@ static inline int p4d_none(p4d_t p4d)		{ return 0; }
>  static inline int p4d_bad(p4d_t p4d)		{ return 0; }
>  static inline int p4d_present(p4d_t p4d)	{ return 1; }
>  static inline void p4d_clear(p4d_t *p4d)	{ }
> +static inline bool p4d_leaf(p4d_t p4d)		{ return false; }
> +#define p4d_leaf p4d_leaf
> +#define pud_ERROR(pud)				(p4d_ERROR((pud).p4d))

[Severity: Low]
Does pud_ERROR() propagate the missing macro issue? It expands to p4d_ERROR(),
which in turn attempts to use the non-existent pgd_ERROR(). This also appears
to result in a compile error if code in include/asm-generic/pgtable-nopud.h
attempts to use it.

>  
>  #define p4d_populate(mm, p4d, pud)		do { } while (0)
>  #define p4d_populate_safe(mm, p4d, pud)		do { } while (0)

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Sashiko AI review · https://sashiko.dev/#/patchset/20260921-dummy_ptxp3-v1-0-cd40cf68242e@arm.com?part=6