Re: [RFC v5 12/38] mm: ability to disable execute permission on a key at creation

On 07/11/2017 03:14 PM, Ram Pai wrote:

Now how many does the kernel use to reserve for itself is something
the kernel knows too and hence can expose it, though the information
may change dynamically as the kernel reserves and releases the key
based on its internal needs. 

So i think we can expose this informaton through procfs/sysfs and let
the application decide how it wants to use the information.

Why bother?  On x86, you'll be told either 14 or 15 depending on whether
you tried to create a mapping in the process without execute permission.
 You can't use all 14 or 15 unless you actually call pkey_alloc() anyway
because the /proc check is inherently racy.

I'm just not sure I see the value in creating a new ABI for it.