linux-kernel - Re: [PATCH v2 02/13] x86/mm: Add p?d

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Date:   Thu, 21 Feb 2019 17:21:26 +0300
From:   "Kirill A. Shutemov" <kirill@...temov.name>
To:     Steven Price <steven.price@....com>
Cc:     linux-mm@...ck.org, Andy Lutomirski <luto@...nel.org>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Arnd Bergmann <arnd@...db.de>, Borislav Petkov <bp@...en8.de>,
        Catalin Marinas <catalin.marinas@....com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Ingo Molnar <mingo@...hat.com>,
        James Morse <james.morse@....com>,
        Jérôme Glisse <jglisse@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Will Deacon <will.deacon@....com>, x86@...nel.org,
        "H. Peter Anvin" <hpa@...or.com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Mark Rutland <Mark.Rutland@....com>,
        "Liang, Kan" <kan.liang@...ux.intel.com>
Subject: Re: [PATCH v2 02/13] x86/mm: Add p?d_large() definitions

On Thu, Feb 21, 2019 at 11:34:51AM +0000, Steven Price wrote:
> Exposing the pud/pgd levels of the page tables to walk_page_range() means
> we may come across the exotic large mappings that come with large areas
> of contiguous memory (such as the kernel's linear map).
> 
> Expose p?d_large() from each architecture to detect these large mappings.
> 
> x86 already has these defined as inline functions, add a macro of the
> same name so we don't end up with the generic version too.
> 
> Signed-off-by: James Morse <james.morse@....com>
> Signed-off-by: Steven Price <steven.price@....com>
> ---
>  arch/x86/include/asm/pgtable.h | 3 +++
>  arch/x86/mm/dump_pagetables.c  | 3 +++
>  2 files changed, 6 insertions(+)
> 
> diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
> index 2779ace16d23..3695f6acb6af 100644
> --- a/arch/x86/include/asm/pgtable.h
> +++ b/arch/x86/include/asm/pgtable.h
> @@ -234,6 +234,7 @@ static inline int pmd_large(pmd_t pte)
>  {
>  	return pmd_flags(pte) & _PAGE_PSE;
>  }
> +#define pmd_large(x)	pmd_large(x)
>  
>  #ifdef CONFIG_TRANSPARENT_HUGEPAGE
>  static inline int pmd_trans_huge(pmd_t pmd)
> @@ -873,6 +874,7 @@ static inline int pud_large(pud_t pud)
>  	return 0;
>  }
>  #endif	/* CONFIG_PGTABLE_LEVELS > 2 */
> +#define pud_large(x)	pud_large(x)

Nit: we usually do this in form of

#define pud_large pud_large

and before body of the inline function.

-- 
 Kirill A. Shutemov