Re: [Xen-devel] kernel oops/IRQ exception when networking between many domUs

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

On 5 Jun 2005, at 17:57, Birger Toedtmann wrote:

> Apparently it is happening somewhere here:
>
> [...]
> 0xc028cbe5 <net_rx_action+1135>:        test   %eax,%eax
> 0xc028cbe7 <net_rx_action+1137>:        je     0xc028ca82 
> <net_rx_action+780>
> 0xc028cbed <net_rx_action+1143>:        mov    %esi,%eax
> 0xc028cbef <net_rx_action+1145>:        shr    $0xc,%eax
> 0xc028cbf2 <net_rx_action+1148>:        mov    %eax,(%esp)
> 0xc028cbf5 <net_rx_action+1151>:        call   0xc028c4c4 <free_mfn>
> 0xc028cbfa <net_rx_action+1156>:        mov    $0xffffffff,%ecx
> ^^^^^^^^^^
Most likely the driver has tried to send a bogus page to a domU. 
Because it's bogus the transfer fails. The driver then tries to free 
the page back to Xen, but that also fails because the page is bogus. 
This confuses the driver, which then BUG()s out.
It's not at all clear where the bogus address comes from: the driver 
basically just reads the address out of an skbuff, and converts it from 
virtual to physical address. But something is obviously going wrong, 
perhaps under memory pressure. :-(
 -- Keir


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