netdev - Re: Regression: net/ipv6/mld running system out of memory (not a leak)

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Date:   Tue, 18 Feb 2020 16:27:53 +0800
From:   Hangbin Liu <liuhangbin@...il.com>
To:     Rafał Miłecki <zajec5@...il.com>
Cc:     Network Development <netdev@...r.kernel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Alexey Kuznetsov <kuznet@....inr.ac.ru>,
        Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        Felix Fietkau <nbd@....name>, John Crispin <john@...ozen.org>,
        Jo-Philipp Wich <jo@...n.io>
Subject: Re: Regression: net/ipv6/mld running system out of memory (not a
 leak)

On Tue, Feb 18, 2020 at 07:55:36AM +0100, Rafał Miłecki wrote:
> I'm sorry for a late reply, I spent that time for switching my devices
> to some newer kernel. I wanted to make sure we are not chasing a bug
> that's long time fixed now.
> 
> This problem still exists in the 5.4.18.

OK, bad news...

> > 
> > Hmm, I'm surprised that IGMP works for you, as it requires enable IPv6
> > forwarding. Do you have a lot IPv6 multicast groups on your device?
> 
> The thing is I don't really use IPv6. There are some single IPv6 packets
> in my network (e.g. MDNS packets) but nothing significant.
> 
> For my testing purposes I access my access points using ssh and it's the
> only real traffic. There are no wireless devices connected to my testing
> devices. They are just running monitor mode interfaces without any real
> traffic.
> 
> > What dose `ip maddr list` show?
> 
> # ip maddr list
> 1:      lo
>         inet  224.0.0.1
>         inet6 ff02::1
>         inet6 ff01::1
> 7:      br-lan
>         link  33:33:00:00:00:01
>         link  33:33:00:00:00:02
>         link  01:00:5e:00:00:01
>         link  33:33:ff:7a:fc:80
>         link  33:33:ff:00:00:00
>         inet  224.0.0.1
>         inet6 ff02::1:ff00:0
>         inet6 ff02::1:ff7a:fc80
>         inet6 ff02::2
>         inet6 ff02::1
>         inet6 ff01::1

No much ipv6 traffic, no much IPv6 multicast groups. Only occurred with
IPv6 forwarding enabled...Any possibility(although unlikely) that there
is a loop for ipv6 multicast traffic under br-lan?

Maybe we can use perf kmem to trace kernel memory statistics.

Thanks
Hangbin