[Babel-users] setsockopt(IPV6_JOIN_GROUP): Cannot allocate memory

[Baptiste Jonglez]

On Thu, Jan 30, 2014 at 12:31:05PM +0100, Julien Muchembled wrote:
> Hello,
> 
> Many (all ?) nodes of our network have babel logs full of the following lines:
> setsockopt(IPV6_JOIN_GROUP): Cannot allocate memory
> setsockopt(IPV6_LEAVE_GROUP): Cannot assign requested address

The kernel has a limit on how much memory each socket may allocate.  Have
a look at the "net.core.optmem_max" sysctl tunable.

According to Documentation/sysctl/net.txt:

   optmem_max
   ----------
   Maximum ancillary buffer size allowed per socket. Ancillary data is a
   sequence of struct cmsghdr structures with appended data.


As far as I understand, it's only used for socket options, not for the
actual buffers of the socket.  Looking at various computers around, a
common value seems to be 20480, while OpenWRT sets this parameter to
10240.

I'm not sure why babeld is hitting this limit (high number of
neighbours?), but you may want to increase it and see if it helps.
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