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Date:   Sun, 26 Aug 2018 15:15:41 -0700
From:   Matthew Wilcox <willy@infradead.org>
To:     Kees Cook <keescook@chromium.org>
Cc:     Thomas Gleixner <tglx@linutronix.de>,
        Andy Lutomirski <luto@amacapital.net>,
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        Michael Ellerman <mpe@ellerman.id.au>
Subject: Re: TLB flushes on fixmap changes
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On Sun, Aug 26, 2018 at 03:03:59PM -0700, Kees Cook wrote:
> I thought the point was that the implementation I suggested was
> NMI-proof? (And in reading Documentation/preempt-locking.txt it sounds
> like disabling interrupts is redundant to preempt_disable()? But I
> don't understand how; it looks like the preempt stuff is advisory?)

Oter way round; disabling interrupts implicitly disables preemption