Re: perf_event_open+clone = unkillable process

From: Thomas Gleixner
Date: Mon Feb 04 2019 - 04:27:30 EST

On Fri, 1 Feb 2019, Dmitry Vyukov wrote:

> On Fri, Feb 1, 2019 at 5:48 PM Dmitry Vyukov <dvyukov@xxxxxxxxxx> wrote:
> >
> > Hello,
> >
> > The following program creates an unkillable process that eats CPU.
> > /proc/pid/stack is empty, I am not sure what other info I can provide.
> >
> > Tested is on upstream commit 4aa9fc2a435abe95a1e8d7f8c7b3d6356514b37a.
> > Config is attached.
> Looking through other reproducers that create unkillable processes, I
> think I found a much simpler reproducer (below). It's single threaded
> and just setups SIGBUS handler and does timer_create+timer_settime to
> send repeated SIGBUS. The resulting process can't be killed with
> +Thomas for timers.

+Oleg, Eric

That's odd. With some tracing I can see that SIGKILL is generated and
queued, but its not delivered by some weird reason. I'm traveling in the
next days, so I won't be able to do much about it. Will look later this