[PATCH] x86, powerpc : pkey-mprotect must allow pkey-0

[Dave Hansen]

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?

We *could* also just not let it be special and let it be freed.  An app
could theoretically be careful and make sure nothing is using it.