linux-kernel - Re: [PATCH 2/3] x86/fpu: Simplify kernel_fpu

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Message-ID: <20190604131138.GB22542@lst.de>
Date:   Tue, 4 Jun 2019 15:11:38 +0200
From:   Christoph Hellwig <hch@....de>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Christoph Hellwig <hch@....de>, x86@...nel.org,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/3] x86/fpu: Simplify kernel_fpu_begin

On Tue, Jun 04, 2019 at 01:47:01PM +0200, Peter Zijlstra wrote:
> > +	if (current->mm && !test_thread_flag(TIF_NEED_FPU_LOAD)) {
> 
> Did that want to be: !(current->flags & PF_KTHREAD), instead?
> 
> Because I'm thinking that kernel_fpu_begin() on a kthread that has
> use_mm() employed shouldn't be doing this..

Well, this is intended to not change semantics.  If we should fix
this is should be a separate patch before or after this series.