From mboxrd@z Thu Jan  1 00:00:00 1970
From: Linus Torvalds <torvalds-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>
Subject: Re: [Bug #11342] Linux 2.6.27-rc3: kernel BUG at mm/vmalloc.c -
 bisected
Date: Tue, 26 Aug 2008 12:09:46 -0700 (PDT)
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To: Mike Travis <travis-sJ/iWh9BUns@public.gmane.org>
Cc: "Alan D. Brunelle" <Alan.Brunelle-VXdhtT5mjnY@public.gmane.org>, Ingo Molnar <mingo-X9Un+BFzKDI@public.gmane.org>, Thomas Gleixner <tglx-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>, "Rafael J. Wysocki" <rjw-KKrjLPT3xs0@public.gmane.org>, Linux Kernel Mailing List <linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, Kernel Testers List <kernel-testers-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, Andrew Morton <akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>, Arjan van de Ven <arjan-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>, Rusty Russell <rusty-8n+1lVoiYb80n/F98K4Iww@public.gmane.org>, "Siddha, Suresh B" <suresh.b.siddha-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>, "Luck, Tony" <tony.luck-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>, Jack Steiner <steiner-sJ/iWh9BUns@public.gmane.org>, Andrew Morton <akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>, Christoph Lameter <cl-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>



On Tue, 26 Aug 2008, Mike Travis wrote:
> 
> The need to allow distros to set NR_CPUS=4096 (and NODES_SHIFT=9) is
> critical to our upcoming SGI systems using what we have been calling
> "UV".

That's fine. You can do it. The default kernel will not, because it's 
clearly not safe.

I really don't care what you do to _your_ images. But I will not 
distribute a known-broken kernel, and I will not debug random stack 
overflows that happen in it.

If you want the default kernel to support 4k cores, we'll need to fix the 
stack usage.  I don't think that is impossible, but IT IS NOT GOING TO 
HAPPEN for 2.6.27.

And quite frankly, if some vendor like RedHat enables NR_CPUS=4096 by 
default, they are totally and utterly crazy.

But some SGI-specific binary that is meant for SGI machines only, and has 
been extensively tested with the setup used on SGI machines is a different 
thing.

			Linus