Re: kernel 2.6.37 : oops in cleanup_once

[Yann Dupont]

Le 02/02/2011 15:53, Eric Dumazet a Ãcrit :
> Le mercredi 02 fÃvrier 2011 Ã 14:08 +0100, Yann Dupont a Ãcrit :
> > Le 02/02/2011 12:24, Eric Dumazet a Ãcrit :
> > > Le mercredi 02 fÃvrier 2011 Ã 11:52 +0100, Eric Dumazet a Ãcrit :
> > > > Le mercredi 02 fÃvrier 2011 Ã 09:53 +0100, Yann Dupont a Ãcrit :
> > > > > Hello.
> > > > > We recently upgraded one machine with vanilla 2.6.37, and experienced 2
> > > > > kernel oops since. Each oops is after ~1 week of uptime.
> > > > > The last oops was last night but we didn't had any trace.
> > > oops, 2.6.37 "only"
> > >
> > > > Yes this is a known problem.
> > > >
> > > > Please try commit 3408404a4c2a4eead9d73b0bbbfe3f225b65f492
> > > > (inetpeer: Use correct AVL tree base pointer in inet_getpeer())
> > > >
> > > > http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=3408404a4c2a4eead9d73b0bbbfe3f225b65f492
> > > >
> > > > I believe David will send it to stable team shortly, if not already
> > > > done :)
> > > Please ignore, this patch was for linux-2.6 tree, 2.6.37 was not
> > > affected by the problem.
> > >
> > > So its another problem... Is there anything particular you do on this
> > > machine ?
> > Nothing really special there, we run a lot (20) of KVM guest (mainly
> > linux firewalls for lots of differents vlan), so we have a lot of
> > bridges vlan&  tun/tap.
> > Oh, and CONFIG_BRIDGE_IGMP_SNOOPING is set to n (because of  the other
> > bug already sent to netdev - more to come on next mail)
> >
> > Hard to say if this BUG is new in 2.6.37. This host was running fine
> > with 2.6.34.2 since August 2010.
> > Bisecting will be hard due to the time to trigger the bug (and the fact
> > that this machine is a production machine)
> >
> > Anyway, I can test with a specific kernel version if you suspect something.
> I suspect a mem corruption from another layer (not inetpeer)
>
> Unfortunately many kmem caches share the "64 bytes" cache.
>
> Could you please add "slub_nomerge" on your boot command ?
Ok, will do it at 18:30 CET (to minimize impact)
It the suspected bug SLUB related ?

The 2.6.34.2 kernel previously used on that server used SLAB.


2 questions :
-How can I be sure slub_nomerge is active ? Boot message ?
-Is there a very severe impact on performance ?

Regards,

--
Yann Dupont - Service IRTS, DSI Università de Nantes
Tel : 02.53.48.49.20 - Mail/Jabber : Yann.Dupont@xxxxxxxxxxxxxx

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