Re: [PATCH 05/11] x86/fpu: set PKRU state for kernel threads

[Dave Hansen]

On 10/19/2018 09:59 AM, Andy Lutomirski wrote:
>> That looks like a good API in general.  The ffs_user_copy_worker that
>> Sebastian mentioned seems to be used by AIO, in which case of course it
>> has to happen in a kernel thread.
>>
>> But while the API is good, deciding on the desired semantics is
>> "interesting".  The submitting thread might be changing PKRU between the
>> time the I/O operation is submitted and the time it is completed, for
>> example.
> I think thereâs only one sensible answer: capture PKRU at the time of submission.

I think it's much more straightforward to just not enforce pkeys.
Having this "phantom" value could cause a very odd, nearly undebuggable
I/O failure.