netdev - Re: [PATCH net 1/2] vxlan: do not modify the shared tunnel info when PMTU triggers an ICMP reply

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Date:   Mon, 31 Jan 2022 14:26:47 +0100
From:   Antoine Tenart <atenart@...nel.org>
To:     Vlad Buslov <vladbu@...dia.com>
Cc:     davem@...emloft.net, kuba@...nel.org, echaudro@...hat.com,
        sbrivio@...hat.com, netdev@...r.kernel.org, pshelar@....org
Subject: Re: [PATCH net 1/2] vxlan: do not modify the shared tunnel info when PMTU triggers an ICMP reply

Quoting Vlad Buslov (2022-01-31 12:26:47)
> On Fri 28 Jan 2022 at 19:01, Antoine Tenart <atenart@...nel.org> wrote:
> >
> > I finally had some time to look at this. Does the diff below fix your
> > issue?
> 
> Yes, with the patch applied I'm no longer able to reproduce memory leak.
> Thanks for fixing this!

Thanks for testing. I'll send a formal patch, can I add your Tested-by?

Also, do you know how to trigger the following code path in OVS
https://elixir.bootlin.com/linux/latest/source/net/openvswitch/actions.c#L944
? Would be good (not required) to test it, to ensure the fix doesn't
break it.

Thanks,
Antoine

> > diff --git a/include/net/dst_metadata.h b/include/net/dst_metadata.h
> > index 14efa0ded75d..90a7a4daea9c 100644
> > --- a/include/net/dst_metadata.h
> > +++ b/include/net/dst_metadata.h
> > @@ -110,8 +110,8 @@ static inline struct metadata_dst *tun_rx_dst(int md_size)
> >  static inline struct metadata_dst *tun_dst_unclone(struct sk_buff *skb)
> >  {
> >         struct metadata_dst *md_dst = skb_metadata_dst(skb);
> > -       int md_size;
> >         struct metadata_dst *new_md;
> > +       int md_size, ret;
> >  
> >         if (!md_dst || md_dst->type != METADATA_IP_TUNNEL)
> >                 return ERR_PTR(-EINVAL);
> > @@ -123,8 +123,15 @@ static inline struct metadata_dst *tun_dst_unclone(struct sk_buff *skb)
> >  
> >         memcpy(&new_md->u.tun_info, &md_dst->u.tun_info,
> >                sizeof(struct ip_tunnel_info) + md_size);
> > +#ifdef CONFIG_DST_CACHE
> > +       ret = dst_cache_init(&new_md->u.tun_info.dst_cache, GFP_ATOMIC);
> > +       if (ret) {
> > +               metadata_dst_free(new_md);
> > +               return ERR_PTR(ret);
> > +       }
> > +#endif
> > +
> >         skb_dst_drop(skb);
> > -       dst_hold(&new_md->dst);
> >         skb_dst_set(skb, &new_md->dst);
> >         return new_md;
> >  }