linux-kernel - Re: [PATCH] hugetlb: ensure we do not reference a surplus page after handing it to buddy

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Date:	Wed, 20 Feb 2008 08:59:34 -0600
From:	Adam Litke <agl@...ibm.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Andy Whitcroft <apw@...dowen.org>,
	Nishanth Aravamudan <nacc@...ibm.com>,
	William Irwin <wli@...omorphy.com>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] hugetlb: ensure we do not reference a surplus page
	after handing it to buddy


On Tue, 2008-02-19 at 15:30 -0800, Andrew Morton wrote:
> On Tue, 19 Feb 2008 12:41:51 -0600 Adam Litke <agl@...ibm.com> wrote:
> 
> > 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@...dowen.org>
> > 
> > Acked-by: Adam Litke <agl@...ibm.com>
> 
> Was I right to assume that this is also needed in 2.6.24.x?

Yep.  Thanks Andrew.

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

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