linux-kernel - Re: [git pull] core, x86: make LIST

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Message-ID: <20080714163402.GB21068@elte.hu>
Date:	Mon, 14 Jul 2008 18:34:02 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Avi Kivity <avi@...ranet.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [git pull] core, x86: make LIST_POISON less deadly


* Linus Torvalds <torvalds@...ux-foundation.org> wrote:

> On Mon, 14 Jul 2008, Avi Kivity wrote:
> > 
> > We could add a printk to the #GP handler that alerts the reader that a
> > poisoned list is suspected, if we find the address pattern in one of the
> > registers.
> 
> I wouldn't worry too much - it's going to be pretty visible anyway.
> 
> The only thing I _would_ worry about is the AMD prefetch bug - some AMD 
> cores raise a spurious page fault for prefetch instructions, and we ignore 
> it.
> 
> I _think_ that bug is a pure TLB issue and would never trigger for an 
> address that doesn't do page fault handling at all because it gets caught 
> in the "is the address valid" code, but it does make me go "Hmm".
> 
> See
> 
> 	http://lkml.org/lkml/2003/9/10/397
> 
> from Rich Brunner. The AMD errata listing does say just page fault, 
> and does talk about speculative TLB reloads, so I think we're all 
> good.

one of my testboxes has this erratum and i saw related bugs in the past 
during stress-tests so it will show up if the non-canonical address 
causes any problems. So i think 0xdead000000000000 will be fine, and 
even if it isnt, we'll catch any problems fast enough.

	Ingo
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