DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 039A8B170
Subject: Re: [PATCH] kernel/watchdog: fix spurious hard lockups
To: Andi Kleen <ak@linux.intel.com>
References: <20170620213309.30051-1-kan.liang@intel.com>
 <4718a252-9515-626e-a69f-565f1c2bc589@redhat.com>
 <20170620230002.GE23705@tassilo.jf.intel.com>
Cc: kan.liang@intel.com, linux-kernel@vger.kernel.org, dzickus@redhat.com,
        mingo@kernel.org, akpm@linux-foundation.org, babu.moger@oracle.com,
        atomlin@redhat.com, torvalds@linux-foundation.org,
        peterz@infradead.org, tglx@linutronix.de, eranian@google.com,
        acme@redhat.com, stable@vger.kernel.org
From: Prarit Bhargava <prarit@redhat.com>
Message-ID: <9320cd00-88f4-49c5-aaa5-4bb4a80c8813@redhat.com>
Date: Tue, 20 Jun 2017 20:12:04 -0400
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On 06/20/2017 07:00 PM, Andi Kleen wrote:
> On Tue, Jun 20, 2017 at 06:34:23PM -0400, Prarit Bhargava wrote:
>>
>>
>> On 06/20/2017 05:33 PM, kan.liang@intel.com wrote:
>>> From: Kan Liang <Kan.liang@intel.com>
>>>
>>> Some users reported spurious NMI watchdog timeouts.
>>>
>>> We now have more and more systems where the Turbo range is wide enough
>>> that the NMI watchdog expires faster than the soft watchdog timer that
>>> updates the interrupt tick the NMI watchdog relies on.
>>>
>>
>> Hmm ... odd that I haven't seen this.  We're running a pretty wide
>> variety of systems here.  Do you have a reproducer?  I'd like to see
>> this occur on production HW.
> 
> It only happens on a few specific CPU SKUs with a very wide Turbo range.

Which ones?

> Reproducer is typically some stress workload that turbos very high.

So stress the single Turbo Max core?  Or any core?

P.

> 
> -Andi
>