linux-kernel - Re: [tip:x86/mm] x86/mm/mtrr: Clean up mtrr_type

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Message-ID: <20150731144452.GA8106@nazgul.tnic>
Date:	Fri, 31 Jul 2015 16:44:52 +0200
From:	Borislav Petkov <bp@...en8.de>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	mingo@...nel.org, hpa@...or.com, dvlasenk@...hat.com, bp@...e.de,
	akpm@...ux-foundation.org, brgerst@...il.com, tglx@...utronix.de,
	linux-mm@...ck.org, luto@...capital.net, mcgrof@...e.com,
	toshi.kani@...com, torvalds@...ux-foundation.org,
	linux-kernel@...r.kernel.org, linux-tip-commits@...r.kernel.org
Subject: Re: [tip:x86/mm] x86/mm/mtrr: Clean up mtrr_type_lookup()

On Fri, Jul 31, 2015 at 03:18:02PM +0200, Peter Zijlstra wrote:
> Using these functions with preemption enabled is racy against MTRR
> updates. And if that race is ok, at the very least explain that it is
> indeed racy and why this is not a problem.

Right, so Luis has been working on burying direct MTRR access so
after that work is done, we'll be using only PAT for changing memory
attributes. Look at arch_phys_wc_add() and all those fbdev users of
mtrr_add() which get converted to that thing...

-- 
Regards/Gruss,
    Boris.

ECO tip #101: Trim your mails when you reply.
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