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Date:   Mon, 18 Feb 2019 12:31:34 +0100
From:   Peter Zijlstra <peterz@infradead.org>
To:     Steven Price <steven.price@arm.com>
Cc:     linux-mm@kvack.org, Andy Lutomirski <luto@kernel.org>,
        Ard Biesheuvel <ard.biesheuvel@linaro.org>,
        Arnd Bergmann <arnd@arndb.de>, Borislav Petkov <bp@alien8.de>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Ingo Molnar <mingo@redhat.com>,
        James Morse <james.morse@arm.com>,
        =?iso-8859-1?B?Suly9G1l?= Glisse <jglisse@redhat.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Will Deacon <will.deacon@arm.com>, x86@kernel.org,
        "H. Peter Anvin" <hpa@zytor.com>,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        kan.liang@linux.intel.com, kirill@shutemov.name
Subject: Re: [PATCH 03/13] mm: Add generic p?d_large() macros
Message-ID: <20190218113134.GU32477@hirez.programming.kicks-ass.net>
References: <20190215170235.23360-1-steven.price@arm.com>
 <20190215170235.23360-4-steven.price@arm.com>
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On Fri, Feb 15, 2019 at 05:02:24PM +0000, Steven Price wrote:
> From: James Morse <james.morse@arm.com>
> 
> 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).
> 
> For architectures that don't provide p?d_large() macros, provided a
> does nothing default.

Kan was going to fix that for all archs I think..

See:

  http://lkml.kernel.org/r/20190204105409.GA17550@hirez.programming.kicks-ass.net

> Signed-off-by: James Morse <james.morse@arm.com>
> Signed-off-by: Steven Price <steven.price@arm.com>
> ---
>  include/asm-generic/pgtable.h | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h
> index 05e61e6c843f..7630d663cd51 100644
> --- a/include/asm-generic/pgtable.h
> +++ b/include/asm-generic/pgtable.h
> @@ -1186,4 +1186,14 @@ static inline bool arch_has_pfn_modify_check(void)
>  #define mm_pmd_folded(mm)	__is_defined(__PAGETABLE_PMD_FOLDED)
>  #endif
>  
> +#ifndef pgd_large
> +#define pgd_large(x)	0
> +#endif
> +#ifndef pud_large
> +#define pud_large(x)	0
> +#endif
> +#ifndef pmd_large
> +#define pmd_large(x)	0
> +#endif
> +
>  #endif /* _ASM_GENERIC_PGTABLE_H */
> -- 
> 2.20.1
>