From mboxrd@z Thu Jan  1 00:00:00 1970
From: Mike Travis <travis-sJ/iWh9BUns@public.gmane.org>
Subject: Re: [Bug #11342] Linux 2.6.27-rc3: kernel BUG at mm/vmalloc.c - bisected
Date: Tue, 26 Aug 2008 12:35:16 -0700
Message-ID: <48B45AF4.8040101@sgi.com>
References: <mzBsPw3QUOF.A.87F.wZGsIB@albercik> <VSpL6AnBTS.A.q9H.6aGsIB@albercik> <alpine.LFD.1.10.0808231257310.3363@nehalem.linux-foundation.org> <alpine.LFD.1.10.0808231313170.3363@nehalem.linux-foundation.org> <48B29F7B.6080405@hp.com> <48B2A421.7080705@hp.com> <alpine.LFD.1.10.0808251019380.3363@nehalem.linux-foundation.org> <alpine.LFD.1.10.0808251106270.3363@nehalem.linux-foundation.org> <48B313E0.1000501@hp.com> <alpine.LFD.1.10.0808251326500.3363@nehalem.linux-foundation.org> <alpine.LFD.1.10.0808251344250.3363@nehalem.linux-foundation.org> <alpine.LFD.1.10.0808251401590.3363@nehalem.linux-foundation.org> <48B452F3.9040304@sgi.com> <alpine.LFD.1.10.0808261205530.3363@nehalem.linux-foundation.org>
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To: Linus Torvalds <torvalds-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@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>, Christoph Lameter <cl-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>

Linus Torvalds wrote:
> 
> 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

Ok, thanks for the reply, and looking into this issue.  We will "strongly
encourage" our distros to base the relevant releases on 2.6.28. :-)  

[Supplying an SGI-specific kernel would not be acceptable to many of our
customers because of the certification issues I mentioned.] 

Mike