Re: GRO + splice panics in 3.7.0-rc5

[Eric Dumazet <eric.dumazet@gmail.com>]

On Thu, 2012-11-15 at 23:28 +0100, Willy Tarreau wrote:
> Hello,
> 
> I was just about to make a quick comparison between LRO and GRO in
> 3.7.0-rc5 to see if LRO still had the big advantage I've always observed,
> but I failed the test because as soon as I enable LRO + splice, the kernel
> panics and reboots.
> 
> I could not yet manage to catch the panic output, I could just reliably
> reproduce it, it crashes instantly.
> 
> All I can say at the moment is the following :
>   - test consist in forwarding HTTP traffic between two NICs via haproxy
>   - driver used was myri10ge
>   - LRO + recv+send : OK
>   - LRO + splice : OK
>   - GRO + recv+send : OK
>   - GRO + splice : panic
>   - no such problem was observed in 3.6.6 so I think this is a recent
>     regression.
> 
> I'll go back digging for more information, but as I'm used to often see
> Eric suggest the right candidates for reverting, I wanted to report the
> issue here in case there are easy ones to try first.

Hi Willy

Nothing particular comes to mind, there were a lot of recent changes
that could trigger this kind of bug.

A stack trace would be useful of course ;)