Re: 2.6.19.1-rt15: BUG in __tasklet_action at kernel/softirq.c:568

Ingo Molnar
2006-12-26T23:43:06Z

* Steven Rostedt <rostedt@goodmis.org> wrote:

> On Wed, 2006-12-20 at 20:50 +0100, Ingo Molnar wrote:
> > * Robert Crocombe <rcrocomb@gmail.com> wrote:
> >
> > > On 12/19/06, Ingo Molnar <mingo@elte.hu> wrote:
> > > >yeah. This is something that triggers very rarely on certain boxes. Not
> > > >fixed yet, and it's been around for some time.
> > >
> > > Is there anything you would like me to do to help diagnose this?
> >
> > to figure out what the bug is :-/ Below is the tasklet redesign patch -
> > the bug must be in there somewhere.
>
> > +static inline int tasklet_tryunlock(struct tasklet_struct *t)
> > +{
> > + return cmpxchg(&t->state, TASKLET_STATEF_RUN, 0) == TASKLET_STATEF_RUN;
> > +}
> > +
>
> This probably isn't it, but is cmpxchg available on all archs now?

yeah, it's probably not related, i saw these failures on plain i686 too,
which definitely has cmpxchg support. The failures i saw happened on a
hyperthreading CPU, so i guess it must be some sort of narrow race.

Ingo