Date: Tue, 21 Mar 2006 21:13:13 +0530
From: Dipankar Sarma <dipankar@in.ibm.com>
To: Eric Dumazet <dada1@cosmosbay.com>
Cc: Jesper Dangaard Brouer <hawk@diku.dk>,
       Robert Olsson <Robert.Olsson@data.slu.se>, jens.laas@data.slu.se,
       hans.liss@its.uu.se, linux-net@vger.kernel.org,
       linux-kernel@vger.kernel.org
Subject: Re: Kernel panic: Route cache, RCU, possibly FIB trie.
Message-ID: <20060321154313.GA9992@in.ibm.com>
Reply-To: dipankar@in.ibm.com
References: <Pine.LNX.4.61.0603202234400.27140@ask.diku.dk> <17439.65413.214470.194287@robur.slu.se> <Pine.LNX.4.61.0603211552590.28173@ask.diku.dk> <44201DAF.7090707@cosmosbay.com>
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On Tue, Mar 21, 2006 at 04:37:19PM +0100, Eric Dumazet wrote:
> Jesper Dangaard Brouer a ?crit :
> >There is definitly high memory pressure on this machine!
> >Slab memory usage, range from 39Mb to 205Mb (at the moment on the 
> >production servers).
> >
> 
> Did you tried 2.6.16 ?
> 
> It contains changes in kernel/rcupdate.c so that not too many RCU elems are 
> queued (force_quiescent_state()). So in the case a rt_cache_flush is done, 
> you have the guarantee all entries are not pushed into rcu at once.

Well, memory pressure or not, the oopses shouldn't be happening :)
Perhaps we should look at them before we work around memory
pressure through the rcu batch tuning stuff in 2.6.16 ?

One of the oopses looked like the rcu callback function pointer 
getting corrupted indicating that it was double freed or
problem with RCU itself.

Thanks
Dipankar
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