Re: [PATCH 4/5] mm: Add PageAnonNotKsm()

[David Hildenbrand <david@xxxxxxxxxx>]

On 02.10.24 17:25, Matthew Wilcox (Oracle) wrote:
> Check that this anonymous page is really anonymous, not
> anonymous-or-KSM.  This optimises the debug check, but its real purpose
> is to remove the last two users of PageKsm().
>
> Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
> ---
>   include/linux/page-flags.h | 11 +++++++++--
>   1 file changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
> index 4c2dfe289046..157c4ffc2fdc 100644
> --- a/include/linux/page-flags.h
> +++ b/include/linux/page-flags.h
> @@ -689,6 +689,13 @@ static __always_inline bool folio_test_anon(const struct folio *folio)
>   	return ((unsigned long)folio->mapping & PAGE_MAPPING_ANON) != 0;
>   }
>   
> +static __always_inline bool PageAnonNotKsm(const struct page *page)
> +{
> +	unsigned long flags = (unsigned long)page_folio(page)->mapping;
> +
> +	return (flags & PAGE_MAPPING_FLAGS) == PAGE_MAPPING_ANON;
> +}
> +
>   static __always_inline bool PageAnon(const struct page *page)
>   {
>   	return folio_test_anon(page_folio(page));
> @@ -1129,14 +1136,14 @@ static __always_inline int PageAnonExclusive(const struct page *page)
>   
>   static __always_inline void SetPageAnonExclusive(struct page *page)
>   {
> -	VM_BUG_ON_PGFLAGS(!PageAnon(page) || PageKsm(page), page);
> +	VM_BUG_ON_PGFLAGS(PageAnonNotKsm(page), page);
>   	VM_BUG_ON_PGFLAGS(PageHuge(page) && !PageHead(page), page);
>   	set_bit(PG_anon_exclusive, &PF_ANY(page, 1)->flags);
>   }
>   
>   static __always_inline void ClearPageAnonExclusive(struct page *page)
>   {
> -	VM_BUG_ON_PGFLAGS(!PageAnon(page) || PageKsm(page), page);
> +	VM_BUG_ON_PGFLAGS(PageAnonNotKsm(page), page);
>   	VM_BUG_ON_PGFLAGS(PageHuge(page) && !PageHead(page), page);
>   	clear_bit(PG_anon_exclusive, &PF_ANY(page, 1)->flags);
>   }

With the "!" added in both cases

Acked-by: David Hildenbrand <david@xxxxxxxxxx>

--
Cheers,

David / dhildenb