syncache errors

[Andre Oppermann]

On 29.08.2010 16:09, Mike Tancsa wrote:
> After upgrading to a recent STABLE, I have been seeing the following sporadic errors
>
> Aug 28 04:15:15 smarthost2 kernel: TCP: [xx.yy.165.120]:53617 to [xx.yy.164.50]:25; syncache_socket:
> Socket create failed due to limits or memory shortage
>
> this is with
> FreeBSD 8.1-STABLE #7: Wed Aug 25 15:32:05 EDT 2010
> and the previous kernel was from July 20th.
>
> The odd thing is that the error is triggered from a RELENG_6 host only it would seem. I noticed
> there are a number of syncache and tcp updates to RELENG_8, is it possible this is related ? I dont
> have any specific tweaks in /etc/sysctl.conf
>
> other than
> net.inet.tcp.log_in_vain: 1
> net.inet.udp.log_in_vain: 1

The log_in_vain sysctl would cause the logging of syncache errors
as well (net.inet.tcp.log_debug).  This was a POLA violation and
I've separated them on August 27 on 8-stable.  So if you update
you won't see them anymore.  That doesn't change the fact that
the socket create failed though.

If it only happens from a RELENG_6 box it probably is a problem
with port re-usage by RELENG_6.  The difficulty is that sonewconn()
fails and doesn't return an error code.  Hence it may be one of
listen queue limits reached, memory shortage or a problem with
inserting the inpcb into the hash lists.

-- 
Andre