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

On 12.02.2020 09:24, Hangbin Liu wrote:

On Wed, Feb 12, 2020 at 08:37:31AM +0100, Rafał Miłecki wrote:

quoted

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?

Hi Rafał,

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.