Messages in this thread | | | Date | Fri, 15 Mar 2013 13:56:59 -0700 | From | Greg KH <> | Subject | Re: [PATCH] perf,x86: fix kernel crash with PEBS/BTS after suspend/resume |
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On Fri, Mar 15, 2013 at 09:49:00PM +0100, Stephane Eranian wrote: > On Fri, Mar 15, 2013 at 9:31 PM, Greg KH <gregkh@linuxfoundation.org> 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@linux-foundation.org> > > > Signed-off-by: Stephane Eranian <eranian@google.com> > > > --- > > > > 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.
Ok, thanks, I've queued it up now there.
greg k-h
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