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Subject: Re: [PATCH] x86, powerpc : pkey-mprotect must allow pkey-0
To: Ram Pai <linuxram@us.ibm.com>
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From: Dave Hansen <dave.hansen@intel.com>
Message-ID: <842bd8a3-d869-f796-32ea-831427fefe4d@intel.com>
Date: Fri, 9 Mar 2018 22:50:33 -0800
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On 03/09/2018 09:55 PM, Ram Pai wrote:
> On Fri, Mar 09, 2018 at 02:40:32PM -0800, Dave Hansen wrote:
>> On 03/09/2018 12:12 AM, Ram Pai wrote:
>>> Once an address range is associated with an allocated pkey, it cannot be
>>> reverted back to key-0. There is no valid reason for the above behavior.  On
>>> the contrary applications need the ability to do so.
>> Why don't we just set pkey 0 to be allocated in the allocation bitmap by
>> default?
> ok. that will make it allocatable. But it will not be associatable,
> given the bug in the current code. And what will be the
> default key associated with a pte? zero? or something else?

I'm just saying that I think we should try to keep from making it
special as much as possible.

Let's fix the bug that keeps it from being associatable.