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

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Date:   Tue, 18 Feb 2020 07:55:36 +0100
From:   Rafał Miłecki <zajec5@...il.com>
To:     Hangbin Liu <liuhangbin@...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)

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.

On Wed, 12 Feb 2020 at 11:08, Hangbin Liu <liuhangbin@...il.com> wrote:
> On Wed, Feb 12, 2020 at 09:49:02AM +0100, Rafał Miłecki wrote:
> > On 12.02.2020 09:24, Hangbin Liu wrote:
> > > Thanks for the report. Although you said this is not a memory leak. Maybe
> > > you can try a84d01647989 ("mld: fix memory leak in mld_del_delrec()").
> >
> > Thanks, that commit was also pointed by Eric and I verified it was
> > backported as:
> > https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=linux-4.9.y&id=df9c0f8a15c283b3339ef636642d3769f8fbc434
> >
> > So it must be some other bug affecting me.
>
> 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.

Monitor interfaces have
	type = ARPHRD_IEEE80211_RADIOTAP
and skbs have
	skb->pkt_type = PACKET_OTHERHOST
	skb->protocol = htons(ETH_P_802_2)
that also shouldn't trigger any IPv6 traffic in the kernel AFAIU.


 > What dose `ip maddr list` show?

# ip maddr list
1:      lo
         inet  224.0.0.1
         inet6 ff02::1
         inet6 ff01::1
2:      eth0
         link  33:33:00:00:00:01
         link  33:33:00:00:00:02 users 2
         link  01:00:5e:00:00:01 users 2
         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 ff05::2
         inet6 ff01::2
         inet6 ff02::2
         inet6 ff02::1
         inet6 ff01::1
3:      eth1
         link  33:33:00:00:00:01
         link  33:33:00:00:00:02 users 2
         inet6 ff05::2
         inet6 ff01::2
         inet6 ff02::2
         inet6 ff02::1
         inet6 ff01::1
4:      eth2
         link  33:33:00:00:00:01
         link  33:33:00:00:00:02 users 2
         inet6 ff05::2
         inet6 ff01::2
         inet6 ff02::2
         inet6 ff02::1
         inet6 ff01::1
5:      wlan0
         link  01:00:5e:00:00:01
         link  33:33:00:00:00:02 users 2
         link  33:33:00:00:00:01
         link  33:33:ff:7a:fc:81
         link  33:33:ff:00:00:00
         inet  224.0.0.1
         inet6 ff02::1:ff00:0
         inet6 ff02::1:ff7a:fc81
         inet6 ff05::2
         inet6 ff01::2
         inet6 ff02::2
         inet6 ff02::1
         inet6 ff01::1
6:      wlan1
         link  01:00:5e:00:00:01
         link  33:33:00:00:00:02 users 2
         link  33:33:00:00:00:01
         link  33:33:ff:7a:fc:88
         link  33:33:ff:00:00:00
         inet  224.0.0.1
         inet6 ff02::1:ff00:0
         inet6 ff02::1:ff7a:fc88
         inet6 ff05::2
         inet6 ff01::2
         inet6 ff02::2
         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
8:      eth0.1
         link  01:00:5e:00:00:01 users 2
         inet  224.0.0.1
         inet6 ff02::2
         inet6 ff02::1
         inet6 ff01::1
9:      mon-phy0
         inet  224.0.0.1
         inet6 ff02::2
         inet6 ff02::1
         inet6 ff01::1
10:     mon-phy1
         inet6 ff02::2
         inet6 ff02::1
         inet6 ff01::1