linux-kernel - Re: [PATCH] arm64: fix pud_huge() for 2-level pagetables

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Message-ID: <20140516100434.GG5624@arm.com>
Date:	Fri, 16 May 2014 11:04:34 +0100
From:	Catalin Marinas <catalin.marinas@....com>
To:	Mark Salter <msalter@...hat.com>
Cc:	Will Deacon <Will.Deacon@....com>,
	Steve Capper <steve.capper@...aro.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] arm64: fix pud_huge() for 2-level pagetables

On Thu, May 15, 2014 at 03:19:22PM +0100, Mark Salter wrote:
> diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c
> index 5e9aec3..9bed38f 100644
> --- a/arch/arm64/mm/hugetlbpage.c
> +++ b/arch/arm64/mm/hugetlbpage.c
> @@ -51,7 +51,11 @@ int pmd_huge(pmd_t pmd)
>  
>  int pud_huge(pud_t pud)
>  {
> +#ifndef __PAGETABLE_PMD_FOLDED
>  	return !(pud_val(pud) & PUD_TABLE_BIT);
> +#else
> +	return 0;
> +#endif
>  }
>  
>  int pmd_huge_support(void)
> @@ -64,8 +68,10 @@ static __init int setup_hugepagesz(char *opt)
>  	unsigned long ps = memparse(opt, &opt);
>  	if (ps == PMD_SIZE) {
>  		hugetlb_add_hstate(PMD_SHIFT - PAGE_SHIFT);
> +#ifndef __PAGETABLE_PMD_FOLDED
>  	} else if (ps == PUD_SIZE) {
>  		hugetlb_add_hstate(PUD_SHIFT - PAGE_SHIFT);
> +#endif

Since PMD_SIZE == PUD_SIZE when __PAGETABLE_PMD_FOLDED, do we need the
#ifndef here? Maybe the compiler is smart enough to remove it but it's
not on a critical path anyway, so I wouldn't bother.

-- 
Catalin
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