Re: [PATCH 1/2] mm: page_isolation: check pfn validity before access

From: Michal Nazarewicz <mina86@mina86.com>
To: Weijie Yang <weijie.yang@samsung.com>,
	kamezawa.hiroyu@jp.fujitsu.com,
	"'Minchan Kim'" <minchan@kernel.org>
Cc: "'Andrew Morton'" <akpm@linux-foundation.org>,
	mgorman@suse.de, "'linux-kernel'" <linux-kernel@vger.kernel.org>,
	"'Linux-MM'" <linux-mm@kvack.org>,
	"'Weijie Yang'" <weijie.yang.kh@gmail.com>
Subject: Re: [PATCH 1/2] mm: page_isolation: check pfn validity before access
Date: Thu, 06 Nov 2014 13:31:14 +0100	[thread overview]
Message-ID: <xa1ta944ik8d.fsf@mina86.com> (raw)
In-Reply-To: <000001cff998$ee0b31d0$ca219570$%yang@samsung.com>

On Thu, Nov 06 2014, Weijie Yang <weijie.yang@samsung.com> wrote:
> In the undo path of start_isolate_page_range(), we need to check
> the pfn validity before access its page, or it will trigger an
> addressing exception if there is hole in the zone.
>
> Signed-off-by: Weijie Yang <weijie.yang@samsung.com>

Acked-by: Michal Nazarewicz <mina86@mina86.com>

> ---
>  mm/page_isolation.c |    7 +++++--
>  1 files changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/mm/page_isolation.c b/mm/page_isolation.c
> index d1473b2..3ddc8b3 100644
> --- a/mm/page_isolation.c
> +++ b/mm/page_isolation.c
> @@ -137,8 +137,11 @@ int start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
>  undo:
>  	for (pfn = start_pfn;
>  	     pfn < undo_pfn;
> -	     pfn += pageblock_nr_pages)
> -		unset_migratetype_isolate(pfn_to_page(pfn), migratetype);
> +	     pfn += pageblock_nr_pages) {
> +		page = __first_valid_page(pfn, pageblock_nr_pages);
> +		if (page)
> +			unset_migratetype_isolate(page, migratetype);
> +	}
>  
>  	return -EBUSY;
>  }
> -- 
> 1.7.0.4
>
>

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