Re: Kernel oops with 2.6.26, padlock and ipsec: probably problem with fpu state changes

Wolfgang Walter
2008-08-09T15:14:48Z

On Saturday 09 August 2008, Herbert Xu wrote:
> On Fri, Aug 08, 2008 at 04:11:21PM -0700, Suresh Siddha wrote:
> >
> > With out the recent dynamic fpu allocation changes, while we don't see
oops,
> > there is a possible race still present in older kernels(for example,
> > while kernel is using kernel_fpu_begin() in some optimized clear/copy
> > page and an interrupt/softirq happens which uses these padlock
> > instructions generating DNA fault).
>
> No this wasn't a problem because kernel_fpu_begin clears TS and
> therefore we don't get faults on SSE instructions.
>
> However, with your patch it will become a problem due to the
> fact that it wasn't designed to be nested.
>

You mean the dynamic fpu allocation patch or the proposed patch for padlock
code?

Thanks,
--
Wolfgang Walter
Studentenwerk München
Anstalt des öffentlichen Rechts
Leiter EDV
Leopoldstraße 15
80802 München
Tel: +49 89 38196-276
Fax: +49 89 38196-144
wolfgang.walter@stwm.de