Message-ID: <418846E9.1060906@us.ibm.com>
Date: Tue, 02 Nov 2004 18:48:09 -0800
From: Dave Hansen <haveblue@us.ibm.com>
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To: Andrea Arcangeli <andrea@novell.com>
CC: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andi Kleen <ak@suse.de>,
       Andrew Morton <akpm@osdl.org>
Subject: Re: fix iounmap and a pageattr memleak (x86 and x86-64)
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Andrea Arcangeli wrote:
> On Tue, Nov 02, 2004 at 05:43:45PM -0800, Dave Hansen wrote:
> 
>>Oh, crap.  I meant to clear ->mapped when change_attr(__pgprot(0)) was 
>>done on it, and set it when it was changed back.  Doing that correctly 
>>preserves the symmetry, right?
> 
> yes it should. I agree with Andrew a bitflag would be enough. I'd call
> it PG_prot_none.

It should be enough, but I don't think we want to waste a bitflag for 
something that's only needed for debugging anyway.  They're getting 
precious these days.  Might as well just bloat the kernel some more when 
the alloc debugging is on.

I'll see what I can do to get some backtraces of the __pg_prot(0) &&
page->mapped cases.
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