Subject: Re: [PATCH] hugetlb: ensure we do not reference a surplus page
	after handing it to buddy
From: Adam Litke <agl@us.ibm.com>
To: Andy Whitcroft <apw@shadowen.org>
Cc: Andrew Morton <akpm@osdl.org>, Nishanth Aravamudan <nacc@us.ibm.com>,
       William Irwin <wli@holomorphy.com>, linux-mm@kvack.org,
       linux-kernel@vger.kernel.org
In-Reply-To: <1203445688.0@pinky>
References: <1203445688.0@pinky>
Content-Type: text/plain
Organization: IBM
Date: Tue, 19 Feb 2008 12:41:51 -0600
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Indeed.  I'll take credit for this thinko...

On Tue, 2008-02-19 at 18:28 +0000, Andy Whitcroft wrote:
> When we free a page via free_huge_page and we detect that we are in
> surplus the page will be returned to the buddy.  After this we no longer
> own the page.  However at the end free_huge_page we clear out our mapping
> pointer from page private.  Even where the page is not a surplus we
> free the page to the hugepage pool, drop the pool locks and then clear
> page private.  In either case the page may have been reallocated.  BAD.
> 
> Make sure we clear out page private before we free the page.
> 
> Signed-off-by: Andy Whitcroft <apw@shadowen.org>

Acked-by: Adam Litke <agl@us.ibm.com>

-- 
Adam Litke - (agl at us.ibm.com)
IBM Linux Technology Center

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