Message-ID: <1428571230.25985.243.camel@edumazet-glaptop2.roam.corp.google.com>
Subject: Re: [BUG REPORT] kernel panic in tcp_sendpage() on null pointer
 dereference
From: Eric Dumazet <eric.dumazet@gmail.com>
To: Tuan Bui <tuan.d.bui@hp.com>
Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, davem@davemloft.net,
        kuznet@ms2.inr.ac.ru, jmorris@namei.org, kaber@trash.net,
        yoshfuji@linux-ipv6.org, Jason Low <jason.low2@hp.com>,
        Aswin Chandramouleeswaran <aswin@hp.com>, Jun Li <jun.li@hp.com>,
        Haris Volos <haris.volos@hp.com>, Wai Long <waiman.long@hp.com>,
        hideaki.yoshifuji@miraclelinux.com, alan@linux.intel.com,
        gw4pts@gw4pts.ampr.org
Date: Thu, 09 Apr 2015 02:20:30 -0700
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	 <1428449613.25985.215.camel@edumazet-glaptop2.roam.corp.google.com>
	 <1428451280.3625.6.camel@u64>
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On Tue, 2015-04-07 at 17:01 -0700, Tuan Bui wrote:
> On Tue, 2015-04-07 at 16:33 -0700, Eric Dumazet wrote:
> > On Tue, 2015-04-07 at 15:57 -0700, Tuan Bui wrote:
> > > Hi all,
> > > 
> > > I am consistently seeing this kernel panic on a 16 sockets machine
> > > running Spark PageRank workload using Docker.  I am running RHEL 7.0
> > > stock kernel which is 3.10.0-123.el7.x86_64.
> > 
> > Have you tried a recent upstream kernel ?
> > 
> 
> Yes I have tried an upstream v4.0-rc4 kernel.  I was still getting the
> same kernel panic.

This looks like a use after free on one skb, but I see no smoking gun in
sendpage() paths.

You might try some debugging kernel build to detect this. (ASAN maybe)


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