Date: Fri, 15 Mar 2013 13:31:23 -0700
From: Greg KH <gregkh@linuxfoundation.org>
To: Stephane Eranian <eranian@google.com>
Cc: linux-kernel@vger.kernel.org, torvalds@linux-foundation.org,
        peterz@infradead.org, mingo@elte.hu, tglx@linutronix.de,
        akpm@linux-foundation.org, acme@redhat.com, jolsa@redhat.com,
        ak@linux.intel.com
Subject: Re: [PATCH] perf,x86: fix kernel crash with PEBS/BTS after
 suspend/resume
Message-ID: <20130315203123.GA28128@kroah.com>
References: <20130315132607.GA4565@quad>
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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?

thanks,

greg k-h
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