Re: Question about qspinlock nest

[Borislav Petkov]

On Fri, Jan 11, 2019 at 10:16:38AM +0100, Peter Zijlstra wrote:
> > Not for debug exception, for MCE exception handler I found below two:
> > 
> > do_machine_check->mce_report_event->schedule_work

That has been the case at least since 2009. We probably never hit it or
I've never seen a deadlock caused by it.

> > do_machine_check->force_sig->force_sig_info

This does:

        ist_begin_non_atomic(regs);
        local_irq_enable();

before forcing the signal. And there's blurb above
ist_begin_non_atomic() why it is OK to schedule when the exception came
from usermode.

-- 
Regards/Gruss,
    Boris.

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