netdev - Re: 4.20-rc6: WARNING: CPU: 30 PID: 197360 at net/core/flow_dissector.c:764 __skb_flow

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Message-ID: <20181220141752.GB861@splinter>
Date:   Thu, 20 Dec 2018 16:17:52 +0200
From:   Ido Schimmel <idosch@...sch.org>
To:     Christian Borntraeger <borntraeger@...ibm.com>
Cc:     willemb@...gle.com, Michael S Tsirkin <mst@...hat.com>,
        netdev@...r.kernel.org,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "virtualization@...ts.linux-foundation.org" 
        <virtualization@...ts.linux-foundation.org>
Subject: Re: 4.20-rc6: WARNING: CPU: 30 PID: 197360 at
 net/core/flow_dissector.c:764 __skb_flow_dissect

On Thu, Dec 20, 2018 at 03:09:22PM +0100, Christian Borntraeger wrote:
> On 20.12.2018 10:12, Ido Schimmel wrote:
> > +Willem
> > 
> > On Thu, Dec 20, 2018 at 08:45:40AM +0100, Christian Borntraeger wrote:
> >> Folks,
> >>
> >> I got this warning today. I cant tell when and why this happened, so I do not know yet how to reproduce.
> >> Maybe someone has a quick idea.
> >>
> >> [85109.572032] WARNING: CPU: 30 PID: 197360 at net/core/flow_dissector.c:764 __skb_flow_dissect+0x1f0/0x1318
> > 
> > I managed to trigger this warning as well the other day, but from a
> > different call path:
> 
> FWIW, it also seems to happen on 4.20-rc1. 4.19.0 seems fine. bisect seem to have failed so
> my reproducer is not reliable.

Yes, it is caused by commit d0e13a1488ad ("flow_dissector: lookup netns
by skb->sk if skb->dev is NULL")

$ git tag --contains d0e13a1488ad
v4.20-rc1
v4.20-rc2
v4.20-rc3
v4.20-rc4
v4.20-rc5
v4.20-rc6