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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Date:	Wed, 18 Jul 2007 19:32:32 +0200
From:	Rene Herman <rene.herman@...il.com>
To:	Phillip Susi <psusi@....rr.com>
CC:	Matt Mackall <mpm@...enic.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...?

On 07/18/2007 07:19 PM, Phillip Susi wrote:

> 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.

As far as I'm aware that's just a consequence of the way linux does memory 
management. If we ignore highmem, virtual memory is simply +/- PAGE_OFFSET 
away from physical so allocating virtually contiguous pages that are _not_ 
physically contiguous requires mapping them somewhere (the vmalloc area) 
which is limited. Given that large number of threads _are_ the problem you 
wouldn't solve things -- you'd again be out of space, although now for a 
different reason.

Rene.
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/