Re: [RFC PATCH 2/4] mm: introduce ptep_get_nopgtable() and set_pte_nopgtable() accessors

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] Compilation breakage due to missing include for `PageTable` in `<linux/pgtable.h>`.
--

--- Patch [2]: [RFC PATCH 2/4] mm: introduce ptep_get_nopgtable() and set_pte_nopgtable() accessors ---
commit 678225e92a04ea7f858c641009b79bba768aafec
Author: Alexander Gordeev <agordeev@linux.ibm.com>

mm: introduce ptep_get_nopgtable() and set_pte_nopgtable() accessors

This patch adds helpers to safely access PTE values stored outside page
tables, such as in stack variables. It updates folio_pte_batch_flags()
and write_protect_page() to use the new accessors.

> diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
> index 8c093c119e5a8..a359e80400986 100644
> --- a/include/linux/pgtable.h
> +++ b/include/linux/pgtable.h
> @@ -489,6 +489,31 @@ static inline int pudp_set_access_flags(struct vm_area_struct *vma,
>  #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
>  #endif
>  
> +#ifndef ptep_get_nopgtable
> +static inline pte_t ptep_get_nopgtable(pte_t *ptep)
> +{
> +	/*
> +	 * Ensure this is a pointer to a copy not a pointer into a page table.
> +	 * If this is a stack value, it won't be a valid virtual address, but
> +	 * that's fine because it also cannot be pointing into the page table.
> +	 */
> +	VM_WARN_ON(virt_addr_valid(ptep) && PageTable(virt_to_page(ptep)));

[Severity: Low]
Does include/linux/pgtable.h need to include <linux/page-flags.h> for the
PageTable() macro?

If a translation unit includes <linux/pgtable.h> without previously including
<linux/page-flags.h>, it looks like the compiler will emit an implicit
function declaration error for PageTable() used here and in
set_pte_nopgtable().

[ ... ]

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/cover.1784292223.git.agordeev@linux.ibm.com?part=2