linux-kernel - Re: [PATCH 1/3] x86/intel_rdt: Fix issue when mkdir uses a freed CLOSid

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Date:   Tue, 11 Apr 2017 11:51:16 -0700 (PDT)
From:   Shivappa Vikas <vikas.shivappa@...el.com>
To:     Thomas Gleixner <tglx@...utronix.de>
cc:     "Luck, Tony" <tony.luck@...el.com>,
        Vikas Shivappa <vikas.shivappa@...ux.intel.com>,
        vikas.shivappa@...el.com, x86@...nel.org,
        linux-kernel@...r.kernel.org, hpa@...or.com, mingo@...nel.org,
        peterz@...radead.org, ravi.v.shankar@...el.com,
        fenghua.yu@...el.com, h.peter.anvin@...el.com
Subject: Re: [PATCH 1/3] x86/intel_rdt: Fix issue when mkdir uses a freed
 CLOSid



On Mon, 10 Apr 2017, Thomas Gleixner wrote:

> On Wed, 5 Apr 2017, Luck, Tony wrote:
>> On Wed, Apr 05, 2017 at 05:20:24PM +0200, Thomas Gleixner wrote:
>>> That's just wrong.
>>>
>>> The proper behaviour for a new control group is, that at the time when it
>>> is created it copies the CBM values of the default group and not claiming
>>> access to ALL of the cache by default.
>>
>> I don't see that as any more helpful. When you make a new
>> control group it is because none of the existing groups
>> provides the QoS that you want.  So the first thing the
>> user will do is write the schemata file with the values
>> they do want.
>>
>> So "all access", or "same as default group" are both the
>> same to the user ... not what they want.
>>
>> We do need to make sure that the schemata matches what is
>> in the registers. We need to make sure that changes to the
>> schemata file result in the MSRs being written where needed.
>
> That's true today. The MSRs and the schemata file of a newly created group
> always match. So there's nothing to fix, right?

Yes. Upstream patch has the MSRs matching with what schemata shows. we can drop 
this patch. I sent a new MBA version without this just on the tip which has the 
other two patches.

Thanks,
Vikas

>
> Thanks,
>
> 	tglx
>
>
>