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Date: Mon, 14 Dec 2015 14:11:08 +0200
From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: yalin wang <yalin.wang2010@gmail.com>
Cc: akpm@linux-foundation.org, kirill.shutemov@linux.intel.com,
        oleg@redhat.com, gang.chen.5i5j@gmail.com, mhocko@suse.com,
        kwapulinski.piotr@gmail.com, aarcange@redhat.com, dcashman@google.com,
        linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [RFC] mm: change find_vma() function
Message-ID: <20151214121107.GB4201@node.shutemov.name>
References: <1450090945-4020-1-git-send-email-yalin.wang2010@gmail.com>
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On Mon, Dec 14, 2015 at 07:02:25PM +0800, yalin wang wrote:
> change find_vma() to break ealier when found the adderss
> is not in any vma, don't need loop to search all vma.
> 
> Signed-off-by: yalin wang <yalin.wang2010@gmail.com>
> ---
>  mm/mmap.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/mm/mmap.c b/mm/mmap.c
> index b513f20..8294c9b 100644
> --- a/mm/mmap.c
> +++ b/mm/mmap.c
> @@ -2064,6 +2064,9 @@ struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
>  			vma = tmp;
>  			if (tmp->vm_start <= addr)
>  				break;
> +			if (!tmp->vm_prev || tmp->vm_prev->vm_end <= addr)
> +				break;
> +

This 'break' would return 'tmp' as found vma.

Have you even tried to test the code?

>  			rb_node = rb_node->rb_left;
>  		} else
>  			rb_node = rb_node->rb_right;
> -- 
> 1.9.1
> 
> --
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-- 
 Kirill A. Shutemov
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