linux-kernel - Re: [PATCH] Fix x86_64 page fault scheduler race

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Message-ID: <20080422132614.GC7311@elte.hu>
Date:	Tue, 22 Apr 2008 15:26:14 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca>
Cc:	akpm@...l.org, "H. Peter Anvin" <hpa@...or.com>,
	Jeremy Fitzhardinge <jeremy@...p.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	"Frank Ch. Eigler" <fche@...hat.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Fix x86_64 page fault scheduler race


* Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca> wrote:

> You are right in that x86_64 does not seems to play as safely as 
> x86_32 on this matter; it uses current->mm. Probably it shouldn't 
> assume "current" is valid. Actually, I don't see where x86_64 disables 
> interrupts around __switch_to, so this would seem to be a race 
> condition. Or have I missed something ?

the scheduler disables interrupts around __switch_to(). (x86 does not 
set __ARCH_WANT_INTERRUPTS_ON_CTXSW)

	Ingo
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