Re: [syzbot] [bpf?] WARNING: ODEBUG bug in tcx_uninstall

[Martin KaFai Lau]

On 7/26/23 11:16 AM, Martin KaFai Lau wrote:
> On 7/26/23 10:01 AM, Leon Romanovsky wrote:
> > On Wed, Jul 26, 2023 at 08:23:12AM -0700, Jakub Kicinski wrote:
> > > On Wed, 26 Jul 2023 10:12:54 +0300 Leon Romanovsky wrote:
> > > > > Thanks, I'll take a look this evening.
> > > >
> > > > Did anybody post a fix for that?
> > > >
> > > > We are experiencing the following kernel panic in netdev commit
> > > > b57e0d48b300 (net-next/main) Merge branch '100GbE' of 
> > > > git://git.kernel.org/pub/scm/linux/kernel/git/tnguy/next-queue
> > >
> > > Not that I know, looks like this is with Daniel's previous fix already
> > > present, and syzbot is hitting it, too :(
> >
> > My naive workaround which restored our regression runs is:
> >
> > diff --git a/kernel/bpf/tcx.c b/kernel/bpf/tcx.c
> > index 69a272712b29..10c9ab830702 100644
> > --- a/kernel/bpf/tcx.c
> > +++ b/kernel/bpf/tcx.c
> > @@ -111,6 +111,7 @@ void tcx_uninstall(struct net_device *dev, bool ingress)
> >                          bpf_prog_put(tuple.prog);
> >                  tcx_skeys_dec(ingress);
> >          }
> > -       WARN_ON_ONCE(tcx_entry(entry)->miniq_active);
> > +       tcx_miniq_set_active(entry, false);
>
> Thanks for the report. I will look into it.

I don't see how that may be triggered for now after Daniel's recent fix in 
commit dc644b540a2d ("tcx: Fix splat in ingress_destroy upon tcx_entry_free"). 
Do you have a small reproducible case? Thanks.

> >          tcx_entry_free(entry);
> >   }