Re: [patch] Real-Time Preemption, -RT-2.6.12-rc1-V0.7.41-00

Paul E. McKenney
2005-03-20T22:41:06Z

On Sat, Mar 19, 2005 at 11:32:59PM -0500, Lee Revell wrote:
> On Sat, 2005-03-19 at 19:50 -0600, K.R. Foley wrote:
> > Lee Revell wrote:
> > > On Sat, 2005-03-19 at 20:16 +0100, Ingo Molnar wrote:
> > >
> > >>the biggest change in this patch is the merge of Paul E. McKenney's
> > >>preemptable RCU code. The new RCU code is active on PREEMPT_RT. While it
> > >>is still quite experimental at this stage, it allowed the removal of
> > >>locking cruft (mainly in the networking code), so it could solve some of
> > >>the longstanding netfilter/networking deadlocks/crashes reported by a
> > >>number of people. Be careful nevertheless.
> > >
> > >
> > > With PREEMPT_RT my machine deadlocked within 20 minutes of boot.
> > > "apt-get dist-upgrade" seemed to trigger the crash. I did not see any
> > > Oops unfortunately.
> > >
> > > Lee
> > >
> >
> > Lee,
> >
> > Just curious. Is this with UP or SMP? I currently have my UP box running
> > PREEMPT_RT, with no problems thus far. However, my SMP box dies while
> > booting (with an oops). I am working on trying to get setup to capture
> > the oops, although it might be tomorrow before I get that done.
> >
>
> UP. It's 100% reproducible, this machine locks up over and over. Seems
> to be associated with network activity by multiple processes.

OK, guess I need to go inspect the uses of synchronize_net() in addition
to synchronize_kernel...

If you do manage to get any additional info, please let me know...

Thanx, Paul