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Date: Mon, 3 Nov 2014 23:57:21 +0100
From: Oleg Nesterov <oleg@redhat.com>
To: Andy Lutomirski <luto@amacapital.net>
Cc: Jan Beulich <jbeulich@suse.com>, Ingo Molnar <mingo@kernel.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
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Subject: Re: [tip:x86/asm] sched/x86_64: Don't save flags on context switch
Message-ID: <20141103225721.GA12117@redhat.com>
References: <bf6fb790787eb95b922157838f52712c25dda157.1412187233.git.luto@amacapital.net> <tip-2c7577a7583747c9b71f26dced7f696b739da745@git.kernel.org> <CALCETrWM2wVynp1rrip9AWtNYDzjC4M8JqKR82ew5dpyrTWMgA@mail.gmail.com> <20141103214712.GA8711@redhat.com> <20141103215837.GB8711@redhat.com> <CALCETrUMLaz_McO=f-v6JmPY7pJSU4M4g1+p1un1UiVcNf+4XQ@mail.gmail.com>
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Argh, sorry for confusion...

On 11/03, Andy Lutomirski wrote:
>
> On Mon, Nov 3, 2014 at 1:58 PM, Oleg Nesterov <oleg@redhat.com> wrote:
> > On 11/03, Oleg Nesterov wrote:
> >>
> > Btw, why retint_kernel() checks "interrupts on" ? It seems to me that
> > that "interrupts off" is not possible, no? And this will be more clear
> > when we remove the "exit_intr" label.
>
> We might get there from #MC or from any of a number of synchronous
> errors (#GP from xyz_safe, #PF from some atomic uaccess thing or a
> vmap fault, etc), and all of those have interrupts off.

Yes, yes, exactly.

I actually tried to say that irqs should be always disabled (afaics!).
IOW "interrupts on" should not be possible, not "interrupts off".

Oleg.