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

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Date:   Thu, 15 Mar 2018 08:55:31 -0700
From:   Dave Hansen <dave.hansen@...el.com>
To:     Thomas Gleixner <tglx@...utronix.de>, Ram Pai <linuxram@...ibm.com>
Cc:     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 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.