FreeBSD 8.0 - network stack crashes?

[Pyun YongHyeon]

On Mon, Nov 30, 2009 at 12:21:16AM +0100, Eirik ??verby wrote:
> On 29. nov. 2009, at 15.29, Robert Watson wrote:
> 
> > On Sun, 29 Nov 2009, Eirik Øverby wrote:
> > 
> >> I just did that (-rxcsum -txcsum -tso), but the numbers still keep rising. I'll wait and see if it goes down again, then reboot with those values to see how it behaves. But right away it doesn't look too good ..
> > 
> > It would be interesting to know if any of the counters in the output of netstat -s grow linearly with the allocation count in netstat -m.  Often times leaks are associated with edge cases in the stack (typically because if they are in common cases the bug is detected really quickly!) -- usually error handling, where in some error case the unwinding fails to free an mbuf that it should free.  These are notoriously hard to track down, unfortunately, but the stats output (especially where delta alloc is linear to delta stat) may inform the situation some more.
> 
> From what I can tell, all that goes up with mbuf usage is traffic/packet counts. I can't say I see anything fishy in there.
> 

If system exhausted all available mbufs it still should not crash
the box. Use -d option of netstat(1) to see whether packet drop
counter still goes up when you know system can't receive any
frames. AFAIK em(4) was carefully written to recover from Rx
resource shortage such that it just drops incoming frames when it
can't get new mbuf. This may result in dropping incoming connection
request but it means it still tries to recover from the resource
exhaustion.
It's not clear where mbuf leak comes from, though.

> From the last few samples in
> http://anduin.net/~ltning/netstat.log

404

> you can see the host stops receiving any packets, but does a few retransmits before the session where this script ran timed out.
> 

By chance do you use pf/ipfw/ipf?

> /Eirik
>