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

From: Ingo Molnar
Date: Thu Nov 20 2014 - 02:45:16 EST

* Andy Lutomirski <luto@xxxxxxxxxxxxxx> wrote:

> On Wed, Nov 19, 2014 at 3:59 PM, Linus Torvalds
> <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:
> > 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.
> >
> No drugs, just imprecision. This series doesn't change NMI
> handling at all. It only changes machine_check int3, debug,
> and stack_segment. (Why is #SS using IST stacks anyway?)

We made most of those preemptible in -rt and changed it away from
the IST. I never got a good explanation from anyone for why they
were IST in the first place - histeric accident or such.

Feel free to clean this up too!


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