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From:   "DSouza, Nelson" <nelson.dsouza@intel.com>
To:     'Peter Zijlstra' <peterz@infradead.org>
CC:     'Tony Jones' <tonyj@suse.com>,
        'Thomas Gleixner' <tglx@linutronix.de>,
        'Stephane Eranian' <eranian@google.com>,
        'Ingo Molnar' <mingo@kernel.org>,
        'Jiri Olsa' <jolsa@redhat.com>,
        'LKML' <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH 1/8] perf/x86/intel: Fix memory corruption
Thread-Topic: [PATCH 1/8] perf/x86/intel: Fix memory corruption
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Date:   Fri, 22 Mar 2019 22:14:26 +0000
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kexec was borked in 5.0+ kernel I was using.

Switched to 5.0.3 stable and kexec works as expected.
No warnings seen with a kexec boot.

-----Original Message-----
From: DSouza, Nelson 
Sent: Thursday, March 21, 2019 4:16 PM
To: Peter Zijlstra <peterz@infradead.org>
Cc: Tony Jones <tonyj@suse.com>; Thomas Gleixner <tglx@linutronix.de>; Stephane Eranian <eranian@google.com>; Ingo Molnar <mingo@kernel.org>; Jiri Olsa <jolsa@redhat.com>; LKML <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH 1/8] perf/x86/intel: Fix memory corruption

Attached cpu hotplug test output while perf is running in the background. No WARN messages seen.

When I run the kexec command, it boots to bios. Haven't used kexec before. Still trying to figure that one out.

-----Original Message-----
From: Peter Zijlstra [mailto:peterz@infradead.org] 
Sent: Thursday, March 21, 2019 1:07 PM
To: DSouza, Nelson <nelson.dsouza@intel.com>
Cc: Tony Jones <tonyj@suse.com>; Thomas Gleixner <tglx@linutronix.de>; Stephane Eranian <eranian@google.com>; Ingo Molnar <mingo@kernel.org>; Jiri Olsa <jolsa@redhat.com>; LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/8] perf/x86/intel: Fix memory corruption

On Thu, Mar 21, 2019 at 07:47:50PM +0000, DSouza, Nelson wrote:
> Is the request to check whether the msr gets reset to default upon reboot of the machine ?

basically:

 - apply patch
 - start workload with 4 counter (on all CPUs), such that tfa-msr=1
 - try the following:
   o cpu hotplug
   o kexec

to see if the new WARN will trigger -- it should not.