Re: XEN/NetBSD panic during loop in the network switch

[Manuel Bouyer <bouyer%antioche.eu.org@localhost>]

On Fri, Sep 26, 2008 at 05:42:37PM +0200, Fredrik Pettai wrote:
> Hi,
> 
> We had a misconfiguration issue on one of our smaller server networks,  
> then our personal manage to make a loop by connecting two switches  
> together over several physical connector, without running any loop  
> protection, like STP or equal.
> 
> We discovered some weird behavior on one of our servers running XEN  
> (3.1.2) / NetBSD 4.0 RELEASE.
> It got panic directly (no other system did that), with a very long  
> console output...
> The only modification made to the running kernel (compared with the  
> XEN3_DOM0) is "options    NMBCLUSTERS=65536".
> 
> The thing that made it more interesting, is that another server  
> running an older version of XEN (3.0.3) / NetBSD 4_BETA2, located in  
> the same switch, didn't say a thing. It just kept running, business as  
> usual...
> 
> Both systems running on the exact same hardware (Dell 2950, the where  
> purchased at the same time, but latter one hasn't been firmware  
> updated (BIOS, raid controller etc.)). Except that the NetBSD source  
> differ (quite much, BETA2 is from feb 2008), the kernel running on the  
> latter system is also a XEN3_DOM0, but slightly stripped conf and with  
> "options    NMBCLUSTERS=4096"
> 
> Anybody else who has experienced the same thing while make loops on  
> the network? :-)
> Or any hints to why the newer XEN/NetBSD system went unhappy?
> 
> Here is the console output:
> 
> panic: bnx0: Double mbuf allocation failure!

It just ran out of memory. This is a know failure mode of the bnx driver;
I think it has been fixed recently (or maybe it was just patches floating
around, I don't remember).

-- 
Manuel Bouyer <bouyer%antioche.eu.org@localhost>
     NetBSD: 26 ans d'experience feront toujours la difference
--