Re: process 'stuck' at exit.

From: Darren Hart
Date: Tue Dec 10 2013 - 16:25:44 EST


On Tue, 2013-12-10 at 15:55 -0500, Dave Jones wrote:
> On Tue, Dec 10, 2013 at 09:34:24PM +0100, Thomas Gleixner wrote:
>
> > > > PS: Oleg - the whole thread is on lkml. Ping me if you need more context.
> > >
> > > btw, I've left the machine in that state, and will for as long as necesary
> > > in case someone has any ideas for further tracing experiments.
> >
> > Can you gather a trace with the function tracer? That will tell us
> > what the thing is actually doing.
>
> Feed me command lines, and I'll see what I can do.
>
> Dave
>

So let's see if we can determine the call chain inside futex_requeue, if
there is one. We want to see if we are calling the following functions:

futex.c: free_pi_state
futex.c: get_futex_value_locked
futex.c: futex_proxy_trylock_atomic
futex.c: lookup_pi_state
futex.c: fault_in_user_writeable

I'm hoping we can make use of ftrace here?

Consider:

$ trace-cmd record -P <PID> -p function -l '*futex*'

And to try outside of futex:

$ trace-cmd record -P <PID> -p function

Then ^C after a few seconds. The trace will be in trace.dat



--
Darren Hart
Intel Open Source Technology Center
Yocto Project - Linux Kernel


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