Re: [PATCH] perf,x86: fix kernel crash with PEBS/BTS after suspend/resume

[Stephane Eranian]

On Fri, Mar 15, 2013 at 9:31 PM, Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
>
> On Fri, Mar 15, 2013 at 02:26:07PM +0100, Stephane Eranian wrote:
> >
> > This patch fixes a kernel crash when using precise sampling (PEBS)
> > after a suspend/resume. Turns out the CPU notifier code is not invoked
> > on CPU0 (BP). Therefore, the DS_AREA (used by PEBS) is not restored properly
> > by the kernel and keeps it power-on/resume value of 0 causing any PEBS
> > measurement to crash when running on CPU0.
> >
> > The workaround is to add a hook in the actual resume code to restore
> > the DS Area MSR value. It is invoked for all CPUS. So for all but CPU0,
> > the DS_AREA will be restored twice but this is harmless.
> >
> > Reported-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
> > Signed-off-by: Stephane Eranian <eranian@xxxxxxxxxx>
> > ---
>
> Is this needed for the 3.8 or older kernels as well?
>
I suspect so. If CPU0 is not covered by the cpu notifiers
then yes, the patch is needed.

>
> thanks,
>
> greg k-h
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