linux-kernel - Re: [PATCH 03/13] mm: Add generic p?d_large() macros

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Message-ID: <aad21496-a86b-ca91-70b7-0c23ea6fefd3@arm.com>
Date:   Mon, 18 Feb 2019 14:19:14 +0000
From:   Steven Price <steven.price@....com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     x86@...nel.org, Arnd Bergmann <arnd@...db.de>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Catalin Marinas <catalin.marinas@....com>,
        kirill@...temov.name, Dave Hansen <dave.hansen@...ux.intel.com>,
        Will Deacon <will.deacon@....com>,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        Jérôme Glisse <jglisse@...hat.com>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Andy Lutomirski <luto@...nel.org>,
        "H. Peter Anvin" <hpa@...or.com>,
        James Morse <james.morse@....com>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-arm-kernel@...ts.infradead.org, kan.liang@...ux.intel.com
Subject: Re: [PATCH 03/13] mm: Add generic p?d_large() macros

On 18/02/2019 11:31, Peter Zijlstra wrote:
> On Fri, Feb 15, 2019 at 05:02:24PM +0000, Steven Price wrote:
>> From: James Morse <james.morse@....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..

The latest series I can find from Kan is still x86 specific. I'm happy
to rebase onto something else if Kan has an implementation already
(please point me in the right direction). Otherwise Kan is obviously
free to base on these changes.

Steve

> See:
> 
>   http://lkml.kernel.org/r/20190204105409.GA17550@hirez.programming.kicks-ass.net
> 
>> Signed-off-by: James Morse <james.morse@....com>
>> Signed-off-by: Steven Price <steven.price@....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
>>
> 
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> linux-arm-kernel@...ts.infradead.org
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> 

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