linux-kernel - Re: [PATCH] i386: improve double fault handling

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Message-ID: <20080731104651.GJ488@elte.hu>
Date:	Thu, 31 Jul 2008 12:46:52 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Chuck Ebbert <cebbert@...hat.com>
Cc:	Jan Beulich <jbeulich@...ell.com>,
	Andi Kleen <andi@...stfloor.org>, tglx@...utronix.de,
	linux-kernel@...r.kernel.org, "H. Peter Anvin" <hpa@...or.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Joerg Roedel <joro@...tes.org>
Subject: Re: [PATCH] i386: improve double fault handling


* Chuck Ebbert <cebbert@...hat.com> wrote:

> Ingo Molnar wrote:
>>
>> All CPUs hitting a double fault simultaneously and corrupting each  
>> others' kernel stack is a theoretical possibility - but is handling it  
>> worth the complexity? It appears to me that a lock plus a short stub  
>> function that takes the lock (with no stack usage) would handle that  
>> much better.
>
> That can't happen now because the TSS gets marked busy so we will get 
> a triple fault instead. One thing we might want to do in the current 
> code is unset the busy flag after handling the fault and before we 
> start looping at the end of the handler so we can handle another fault 
> later.

that would be a nice improvement.

	Ingo
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