linux-kernel - Re: [PATCH][RFC] 4K stacks default, not a debug thing any more...?

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Message-ID: <20070718183252.264fe6b2@the-village.bc.nu>
Date:	Wed, 18 Jul 2007 18:32:52 +0100
From:	Alan Cox <alan@...rguk.ukuu.org.uk>
To:	Phillip Susi <psusi@....rr.com>
Cc:	Matt Mackall <mpm@...enic.com>,
	Rene Herman <rene.herman@...il.com>,
	Jeremy Fitzhardinge <jeremy@...p.org>,
	Jesper Juhl <jesper.juhl@...il.com>,
	Ray Lee <ray-lk@...rabbit.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	William Lee Irwin III <wli@...omorphy.com>,
	David Chinner <dgc@....com>
Subject: Re: [PATCH][RFC] 4K stacks default, not a debug thing any more...?

> Why do the two pages have to be physically contiguous?  The stack just 
> needs to be two contiguous pages in virtual memory, but they can map to 
> any two pages anywhere in physical memory.

Historically we allowed DMA off the stack on old x86 systems. Removing
that while a good idea would take a lot of auditing. We also have a very
limited vmalloc window for mapped pages and filling that with stacks
would be bad.
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