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

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Date:   Wed, 12 Feb 2020 09:46:26 +0100
From:   Rafał Miłecki <zajec5@...il.com>
To:     Eric Dumazet <eric.dumazet@...il.com>,
        Network Development <netdev@...r.kernel.org>,
        Hangbin Liu <liuhangbin@...il.com>,
        "David S. Miller" <davem@...emloft.net>
Cc:     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 12.02.2020 08:59, Eric Dumazet wrote:
> On 2/11/20 11:37 PM, Rafał Miłecki wrote:
>> Hi, I need some help with my devices running out of memory. I've
>> debugging skills but I don't know net subsystem.
>>
>> I run Linux based OpenWrt distribution on home wireless devices (ARM
>> routers and access points with brcmfmac wireless driver). I noticed
>> that using wireless monitor mode interface results in my devices (128
>> MiB RAM) running out of memory in about 2 days. This is NOT a memory
>> leak as putting wireless down brings back all the memory.
>>
>> Interestingly this memory drain requires at least one of:
>> net.ipv6.conf.default.forwarding=1
>> net.ipv6.conf.all.forwarding=1
>> to be set. OpenWrt happens to use both by default.
>>
>> This regression was introduced by the commit 1666d49e1d41 ("mld: do
>> not remove mld souce list info when set link down") - first appeared
>> in 4.10 and then backported. This bug exists in 4.9.14 and 4.14.169.
>> Reverting that commit from 4.9.14 and 4.14.169 /fixes/ the problem.
>>
>> Can you look at possible cause/fix of this problem, please? Is there
>> anything I can test or is there more info I can provide?
>>
>> I'm not sure why this issue appears only when using monitor mode.
>> Using wireless __ap mode interface (with hostapd) won't expose this
>> issue. I guess it may be a matter of monitor interfaces not being
>> bridged?
>>
> 
> This commit had few fixes, are you sure they were applied to your kernel ?

Thanks for looking at this! Unfortunately I already have all listed
patches so it has to be yet another issue.


> 9c8bb163ae784be4f79ae504e78c862806087c54 igmp, mld: Fix memory leak in igmpv3/mld_del_delrec()

First included in v4.10-rc8, so it's present in my 4.14.169.


> 08d3ffcc0cfaba36f6b86fd568cc3bc773061fa6 multicast: do not restore deleted record source filter mode to new one
First included in v4.18-rc8, so it's present in my 4.14.169.


> a84d016479896b5526a2cc54784e6ffc41c9d6f6 mld: fix memory leak in mld_del_delrec()
Backported to linux-4.14.y as df9c0f8a15c283b3339ef636642d3769f8fbc434
and first included in v4.14.143, so it's present in my 4.14.169.