linux-kernel - Re: [PATCH v3] x86: treat pkey-0 special

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Message-ID: <alpine.DEB.2.21.1803151713050.1525@nanos.tec.linutronix.de>
Date:   Thu, 15 Mar 2018 17:13:16 +0100 (CET)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Dave Hansen <dave.hansen@...el.com>
cc:     Ram Pai <linuxram@...ibm.com>, mingo@...hat.com,
        mpe@...erman.id.au, linuxppc-dev@...ts.ozlabs.org,
        linux-mm@...ck.org, x86@...nel.org, linux-arch@...r.kernel.org,
        linux-kernel@...r.kernel.org, akpm@...ux-foundation.org,
        benh@...nel.crashing.org, paulus@...ba.org,
        khandual@...ux.vnet.ibm.com, aneesh.kumar@...ux.vnet.ibm.com,
        bsingharora@...il.com, hbabu@...ibm.com, mhocko@...nel.org,
        bauerman@...ux.vnet.ibm.com, ebiederm@...ssion.com, corbet@....net,
        arnd@...db.de, fweimer@...hat.com, msuchanek@...e.com,
        Ulrich.Weigand@...ibm.com
Subject: Re: [PATCH v3] x86: treat pkey-0 special

On Thu, 15 Mar 2018, Dave Hansen wrote:

> On 03/15/2018 02:46 AM, Thomas Gleixner wrote:
> >> +	if (!pkey || !mm_pkey_is_allocated(mm, pkey))
> > Why this extra check? mm_pkey_is_allocated(mm, 0) should not return true
> > ever. If it does, then this wants to be fixed.
> 
> I was thinking that we _do_ actually want it to seem allocated.  It just
> get "allocated" implicitly when an mm is created.  I think that will
> simplify the code if we avoid treating it specially in as many places as
> possible.

That works as well.