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

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Message-ID: <20130315203123.GA28128@kroah.com>
Date:	Fri, 15 Mar 2013 13:31:23 -0700
From:	Greg KH <gregkh@...uxfoundation.org>
To:	Stephane Eranian <eranian@...gle.com>
Cc:	linux-kernel@...r.kernel.org, torvalds@...ux-foundation.org,
	peterz@...radead.org, mingo@...e.hu, tglx@...utronix.de,
	akpm@...ux-foundation.org, acme@...hat.com, jolsa@...hat.com,
	ak@...ux.intel.com
Subject: Re: [PATCH] perf,x86: fix kernel crash with PEBS/BTS after
 suspend/resume

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@...ux-foundation.org>
> Signed-off-by: Stephane Eranian <eranian@...gle.com>
> ---

Is this needed for the 3.8 or older kernels as well?

thanks,

greg k-h
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