Bug#511103: apache2-mpm-prefork: MPM Prefork/Itk Segmentation fault under heavy load

["Stefan Fritsch" <sf@sfritsch.de>]

> With the Lenny's kernel (2.6.26-1-amd64), I can't reproduce the bug
> but there is an error message on the console :
>
>  [  123.197934] TCPv6: Possible SYN flooding on port 80. Dropping request.
>
> I've joined my custom kernel config (I'm using the same base for 150
> servers
> and it's the first time there is such issue).

This is https://issues.apache.org/bugzilla/show_bug.cgi?id=46467 . Try (on
2.6.27)

echo 1024 >  /proc/sys/fs/epoll/max_user_instances

where 1024 is some value larger than MaxClients, then it should work. The
above bug report also has a patch that makes apache log an error message
instead of segfaulting.

Cheers,
Stefan