netdev - Re: Bug, kernel panic, NULL dereference , cleanup_once / icmp_route_lookup.clone.19.clone / nat , 2.6.39-rc7-git11

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Date:	Thu, 19 May 2011 08:30:23 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Denys Fedoryshchenko <denys@...p.net.lb>
Cc:	netdev@...r.kernel.org, David Miller <davem@...emloft.net>
Subject: Re: Bug, kernel panic, NULL dereference , cleanup_once /
 icmp_route_lookup.clone.19.clone / nat , 2.6.39-rc7-git11

Le jeudi 19 mai 2011 à 09:11 +0300, Denys Fedoryshchenko a écrit :
> On Thu, 19 May 2011 07:19:57 +0200, Eric Dumazet wrote:
> > Le mercredi 18 mai 2011 à 21:29 +0200, Eric Dumazet a écrit :
> >> Le mercredi 18 mai 2011 à 17:52 +0200, Eric Dumazet a écrit :
> >>
> >> > Hmm, it seems we have some inetpeer refcount leak somewhere.
> >> >
> >> > Maybe one (struct rtable)->peer is not released on dst/rtable 
> >> removal,
> >> > or we also leak dst/rtable (and their ->peer inetpeer)
> >> >
> >> > Watch :
> >> >
> >> > grep peer /proc/slabinfo
> >> > grep dst /proc/slabinfo
> >> >
> >>
> >> FYI, I started a bisection to find the faulty commit.
> >>
> >
> > Oh well, of course this came to 2c8cec5c10bced240
> > (ipv4: Cache learned PMTU information in inetpeer.)
> >
> > So my method to check if we have a leak might be wrong, since the 
> > above
> > commit let cache full of garbage, and hope that following lookups 
> > will
> > find and evict obsolete dst.
> >
> > Thats getting difficult :(
> >
> > Could you please send us
> >
> > grep . /proc/sys/net/ipv4/route/*
> >
> > Thanks !
>  NewNet-PPPoE ~ # grep . /proc/sys/net/ipv4/route/*
>  /proc/sys/net/ipv4/route/error_burst:5000
>  /proc/sys/net/ipv4/route/error_cost:1000
>  grep: /proc/sys/net/ipv4/route/flush: Permission denied
>  /proc/sys/net/ipv4/route/gc_elasticity:8
>  /proc/sys/net/ipv4/route/gc_interval:60
>  /proc/sys/net/ipv4/route/gc_min_interval:0
>  /proc/sys/net/ipv4/route/gc_min_interval_ms:500
>  /proc/sys/net/ipv4/route/gc_thresh:32768
>  /proc/sys/net/ipv4/route/gc_timeout:300
>  /proc/sys/net/ipv4/route/max_size:524288
>  /proc/sys/net/ipv4/route/min_adv_mss:256
>  /proc/sys/net/ipv4/route/min_pmtu:552
>  /proc/sys/net/ipv4/route/mtu_expires:600
>  /proc/sys/net/ipv4/route/redirect_load:20
>  /proc/sys/net/ipv4/route/redirect_number:9
>  /proc/sys/net/ipv4/route/redirect_silence:20480
> 
>  I think it is default one.
> 
>  PMTU is very actual for that, as it is pppoe, and up to 2k interfaces 
>  terminated there.
> 

Yes, and every time an interface is added -> new route added, route
cache is invalidated (we change rt_genid)

>  I don't know, if it matters, but
>  iptables -A FORWARD -p tcp --tcp-flags SYN,RST SYN -j TCPMSS 
>  --clamp-mss-to-pmtu
>  also there.
> 
>  I can generate and put "ip route ls cache" and any other info.
> 

Hmm would you please send :

rtstat -c10 -i1



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