From mboxrd@z Thu Jan  1 00:00:00 1970
From: Dave Hansen <dave.hansen@intel.com>
Subject: Re: [PATCH 08/10] x86, pkeys: default to a restrictive init PKRU
Date: Fri, 29 Jul 2016 10:50:51 -0700
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To: Andy Lutomirski <luto@amacapital.net>
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On 07/29/2016 10:29 AM, Andy Lutomirski wrote:
>> > In the end, this ensures that threads which do not know how to
>> > manage their own pkey rights can not do damage to data which is
>> > pkey-protected.
> I think you missed the fpu__clear() caller in kernel/fpu/signal.c.
> 
> ISTM it might be more comprehensible to change fpu__clear in general
> and then special case things you want to behave differently.

The code actually already patched the generic fpu__clear():

	fpu__clear() ->
	copy_init_fpstate_to_fpregs() ->
	copy_init_pkru_to_fpregs()

So I think it hit the case you are talking about.