linux-kernel - Re: x86/mm/pageattr: Code without effect?

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Message-ID: <20130408125129.GC4395@pd.tnic>
Date:	Mon, 8 Apr 2013 14:51:29 +0200
From:	Borislav Petkov <bp@...en8.de>
To:	Stefan Bader <stefan.bader@...onical.com>
Cc:	Ingo Molnar <mingo@...nel.org>,
	Andrea Arcangeli <aarcange@...hat.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Andy Whitcroft <apw@...onical.com>,
	Mel Gorman <mgorman@...e.de>
Subject: Re: x86/mm/pageattr: Code without effect?

On Mon, Apr 08, 2013 at 02:28:47PM +0200, Stefan Bader wrote:
> To enforce the PSE bit here sounds reasonably right. And also apply
> canon_pgprot, too. GLOBAL I don't know for sure.

Well sure, you don't want to flush those from the TLB if it is kernel
memory since it is mapped in every process AFAICT.

> By the way there is a usage of new_prot a bit down of
> try_preserve_large_page which probably should be changed into
> req_prot, too. That was enforcing the canon_pgprot before the change.
> So that may be considered a regression to before.

Which one?

Actually, after Andrea's patch it all makes sense - we initialize
new_prot from req_prot *after* all protections checks. new_prot are,
IMHO, the final protection bits which we are actually going to change.

-- 
Regards/Gruss,
    Boris.

Sent from a fat crate under my desk. Formatting is fine.
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