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

[Ram Pai]

On Fri, Mar 09, 2018 at 09:19:53PM +1100, Michael Ellerman wrote:
> Ram Pai <linuxram at us.ibm.com> writes:
> 
> > 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.
> 
> Please explain this in much more detail. Is it an ABI change?

Not necessarily an ABI change. older binary applications  will continue
to work. It can be considered as a bug-fix.

> 
> And why did we just notice this?

Yes. this was noticed by an application vendor.

> 
> > The patch relaxes the restriction.
> >
> > Tested on powerpc and x86_64.
> 
> Thanks, but please split the patch, one for each arch.

Will do.
RP