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

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Message-ID: <20170405180737.GA4850@intel.com>
Date:   Wed, 5 Apr 2017 11:07:37 -0700
From:   "Luck, Tony" <tony.luck@...el.com>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     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 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.

-Tony