linux-kernel - Re: [PATCH] hugetlb: Fix clear_user

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Message-Id: <20070928114526.3398c462.akpm@linux-foundation.org>
Date:	Fri, 28 Sep 2007 11:45:26 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Ralf Baechle <ralf@...ux-mips.org>
Cc:	linux-kernel@...r.kernel.org, linux-mips@...ux-mips.org
Subject: Re: [PATCH] hugetlb: Fix clear_user_highpage arguments

On Fri, 28 Sep 2007 17:35:45 +0100 Ralf Baechle <ralf@...ux-mips.org> wrote:

> The virtual address space argument of clear_user_highpage is supposed to
> be the virtual address where the page being cleared will eventually be
> mapped. This allows architectures with virtually indexed caches a few
> clever tricks.  That sort of trick falls over in painful ways if the
> virtual address argument is wrong.

yeah, but only if you're using a weird CPU architecture ;)

> Signed-off-by: Ralf Baechle <ralf@...ux-mips.org>
> 
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index 84c795e..eab8c42 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -42,7 +42,7 @@ static void clear_huge_page(struct page *page, unsigned long addr)
>  	might_sleep();
>  	for (i = 0; i < (HPAGE_SIZE/PAGE_SIZE); i++) {
>  		cond_resched();
> -		clear_user_highpage(page + i, addr);
> +		clear_user_highpage(page + i, addr + i * PAGE_SIZE);
>  	}
>  }
>  

I'll add this to the 2.6.23 queue.  Is it needed in 2.6.22.x?
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