Re: [PATCH v3 3/3] sched, x86: Check that we're on the right stack in schedule and __might_sleep

[Linus Torvalds]

On Wed, Nov 19, 2014 at 3:49 PM, Andy Lutomirski <luto@xxxxxxxxxxxxxx> wrote:
>
> My only real objection is that it's going to be ugly and error prone.
> It'll have to be something like:

No.

> because the whole point of this series is to make the IST entries not
> be atomic when they come from userspace.

Andy,  you need to lay off the drugs.

NMI absolutely *has* to be atomic. The whole "oh, there's a per-core
NMI flag and it disables all other NMI's and interrupts" kind of
enforces that.

Trust me. Talking about being able to preempt the NMI handler is just
crazy talk.

                    Linus
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