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

From: Andy Lutomirski
Date: Wed Nov 19 2014 - 18:04:28 EST

On Wed, Nov 19, 2014 at 11:44 AM, Linus Torvalds
<torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:
> On Wed, Nov 19, 2014 at 11:29 AM, Andi Kleen <andi@xxxxxxxxxxxxxx> wrote:
>> The exception handlers which use the IST stacks don't necessarily
>> set irq count. Maybe they should.
> Hmm. I think they should. Since they clearly must not schedule, as
> they use a percpu stack.
> Which exceptions use IST?
> [ grep grep ]
> Looks like stack, doublefault, nmi, debug and mce. And yes, I really
> think they should all raise the irq count if they don't already.
> Rather than add random arch-specific "let's check that we're on the
> right stack" code to the might-sleep stuff, just use the one we have.

Does that include nmi? I'm a bit afraid of touching that code.

It's certainly easy enough to bump irq_count in the paranoid entries.


> Linus

Andy Lutomirski
AMA Capital Management, LLC
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