Re: [PATCH 0/6] [git pull] updates for tip/tracing/ftrace

Ingo Molnar
2009-02-19T08:18:18Z

* Frederic Weisbecker <fweisbec@gmail.com> wrote:

> > the function-graph-tracer started locking up since the last
> > batch of changes:
> >
> > Testing tracer sysprof: .. no entries found ..FAILED!
> > initcall 0xffffffff812e91d1 returned -1 after 101562 usecs
> > initcall 0xffffffff812e91d1 returned with error code -1
> > calling 0xffffffff812e91e3 @ 1
> > Testing tracer function: PASSED
> > Testing dynamic ftrace:
> > [hard lockup]
>
> I've successfully reproduced it with your config.
> Note that I didn't built the function graph tracer.
>
> I also tried to set ftrace=nop as a parameter to avoid the selftests and then
> enabled the function tracer after the boot. And then I had no problem.
>
> Looks like it happens during dynamic ftrace initialization.
> Perhaps a problem with the recent mutex conversion and kstopmachine, which
> could result in a hardlockup in case of a deadlock.
>
> But lockdep didn't say anything.
> I'm reverting some of the last patches and will see.

Frederic, Steve, any progress on this bug? It's blocking all new
tracing patches.

Ingo