Nginx 1.0 + IPv6 kills server when accessed over IPv6

[Maxim Dounin]

Hello!

On Mon, Apr 18, 2011 at 05:26:25PM +0000, Egill R. Erlendsson | Grapewire wrote:

> I just upgraded from 0.8.54 to 1.0 (I've also tried various versions of
> 0.9.x experiencing the same issue).
> 
> Running 2.6.35-28-generic #50-Ubuntu SMP on a 64bit Ubuntu 10.10
> 
> As soon as I try to open a connection to an ipv6 enabled site via ipv6 - the
> server just hangs instantly, requiring a hard reboot (nothing is dumped to
> any logs).
> 
> Since the server is located in another country I've only managed to grab a
> screenshot of the KVM:
> http://i55.tinypic.com/dfkuc2.png
> 
> This does not happen when using 0.8.54 (or any other 0.8.x version I've used
> before).
> 
> Not sure if this is an Nginx issue, kernel issue, hardware issue, but I
> thought this would be the best place to start.
> Has anyone else experienced something similar?

Obviously "server just hangs" means this isn't nginx issue.  Most 
likely it's kernel problem, though it may be triggered by 
something nginx does (in recent versions).

I suspect the following changes in nginx may be problematic:

1. Use of accept4() syscall, as of 0.9.0+.

2. Listen backlog -1 on Linux, as of 0.9.5+.

Could you please test which exactly version causes problems (and 
which one is last working)?

Maxim Dounin