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Date:   Thu, 15 Mar 2018 10:21:29 -0700
From:   Ram Pai <linuxram@us.ibm.com>
To:     Dave Hansen <dave.hansen@intel.com>
Cc:     Thomas Gleixner <tglx@linutronix.de>, mingo@redhat.com,
        mpe@ellerman.id.au, linuxppc-dev@lists.ozlabs.org,
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        Ulrich.Weigand@de.ibm.com
Subject: Re: [PATCH v3] x86: treat pkey-0 special
Reply-To: Ram Pai <linuxram@us.ibm.com>
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On Thu, Mar 15, 2018 at 08:55:31AM -0700, 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.

I think, the logic that makes pkey-0 special must to go
in arch-neutral code.   How about checking for pkey-0 in sys_pkey_free()
itself?

RP