linux-kernel - Re: [PATCH v13 6/8] arm: add pmd

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Date:	Fri, 18 Jul 2014 15:54:22 +0100
From:	Steve Capper <steve.capper@...aro.org>
To:	Minchan Kim <minchan@...nel.org>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	Michael Kerrisk <mtk.manpages@...il.com>,
	Linux API <linux-api@...r.kernel.org>,
	Hugh Dickins <hughd@...gle.com>,
	Johannes Weiner <hannes@...xchg.org>,
	Rik van Riel <riel@...hat.com>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	Mel Gorman <mgorman@...e.de>, Jason Evans <je@...com>,
	Zhang Yanfei <zhangyanfei@...fujitsu.com>,
	"Kirill A. Shutemov" <kirill@...temov.name>,
	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will.deacon@....com>,
	Russell King <linux@....linux.org.uk>,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v13 6/8] arm: add pmd_[dirty|mkclean] for THP

On Fri, Jul 18, 2014 at 03:53:04PM +0900, Minchan Kim wrote:
> MADV_FREE needs pmd_dirty and pmd_mkclean for detecting recent
> overwrite of the contents since MADV_FREE syscall is called for
> THP page.
> 
> This patch adds pmd_dirty and pmd_mkclean for THP page MADV_FREE
> support.
> 
> Cc: Catalin Marinas <catalin.marinas@....com>
> Cc: Will Deacon <will.deacon@....com>
> Cc: Steve Capper <steve.capper@...aro.org>
> Cc: Russell King <linux@....linux.org.uk>
> Cc: linux-arm-kernel@...ts.infradead.org
> Signed-off-by: Minchan Kim <minchan@...nel.org>

This patch looks good to me:
Acked-by: Steve Capper <steve.capper@...aro.org>

There is another patch that introduces a helper function to test for
pmd bits, please see below.

> ---
>  arch/arm/include/asm/pgtable-3level.h | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/arch/arm/include/asm/pgtable-3level.h b/arch/arm/include/asm/pgtable-3level.h
> index 85c60adc8b60..830f84f2d277 100644
> --- a/arch/arm/include/asm/pgtable-3level.h
> +++ b/arch/arm/include/asm/pgtable-3level.h
> @@ -220,6 +220,8 @@ static inline pmd_t *pmd_offset(pud_t *pud, unsigned long addr)
>  #define pmd_trans_splitting(pmd) (pmd_val(pmd) & PMD_SECT_SPLITTING)
>  #endif
>  
> +#define pmd_dirty(pmd)		(pmd_val(pmd) & PMD_SECT_DIRTY)

Russell,
Should this be folded into my {pte|pmd}_isset patch?
http://lists.infradead.org/pipermail/linux-arm-kernel/2014-July/268979.html

Cheers,
-- 
Steve


> +
>  #define PMD_BIT_FUNC(fn,op) \
>  static inline pmd_t pmd_##fn(pmd_t pmd) { pmd_val(pmd) op; return pmd; }
>  
> @@ -228,6 +230,7 @@ PMD_BIT_FUNC(mkold,	&= ~PMD_SECT_AF);
>  PMD_BIT_FUNC(mksplitting, |= PMD_SECT_SPLITTING);
>  PMD_BIT_FUNC(mkwrite,   &= ~PMD_SECT_RDONLY);
>  PMD_BIT_FUNC(mkdirty,   |= PMD_SECT_DIRTY);
> +PMD_BIT_FUNC(mkclean,   &= ~PMD_SECT_DIRTY);
>  PMD_BIT_FUNC(mkyoung,   |= PMD_SECT_AF);
>  
>  #define pmd_mkhuge(pmd)		(__pmd(pmd_val(pmd) & ~PMD_TABLE_BIT))
> -- 
> 2.0.0
> 
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