Re: [PATCH 0/5] srcu fixes

Paul E. McKenney
2023-10-04T03:21:47Z

On Tue, Oct 03, 2023 at 05:35:31PM -0700, Paul E. McKenney wrote:
> On Wed, Oct 04, 2023 at 01:28:58AM +0200, Frederic Weisbecker wrote:
> > Hi,
> >
> > This contains a fix for "SRCU: kworker hung in synchronize_srcu":
> >
> > http://lore.kernel.org/CANZk6aR+CqZaqmMWrC2eRRPY12qAZnDZLwLnHZbNi=xXMB401g@mail.gmail.com
> >
> > And a few cleanups.
> >
> > Passed 50 hours of SRCU-P and SRCU-N.
> >
> > git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks.git
> > srcu/fixes
> >
> > HEAD: 7ea5adc5673b42ef06e811dca75e43d558cc87e0
> >
> > Thanks,
> > Frederic
>
> Very good, and a big "Thank You!!!" to all of you!
>
> I queued this series for testing purposes, and have started a bunch of
> SRCU-P and SRCU-N tests on one set of systems, and a single SRCU-P and
> SRCU-N on another system, but with both scenarios resized to 40 CPU each.
>
> While that is in flight, a few questions:
>
> o Please check the Co-developed-by rules. Last I knew, it was
> necessary to have a Signed-off-by after each Co-developed-by.
>
> o Is it possible to get a Tested-by from the original reporter?
> Or is this not reproducible?
>
> o Is it possible to convince rcutorture to find this sort of
> bug? Seems like it should be, but easy to say...

And one other thing...

o What other bugs like this one are hiding elsewhere
in RCU?

> o Frederic, would you like to include this in your upcoming
> pull request? Or does it need more time?

Thanx, Paul

> > ---
> >
> > Frederic Weisbecker (5):
> > srcu: Fix callbacks acceleration mishandling
> > srcu: Only accelerate on enqueue time
> > srcu: Remove superfluous callbacks advancing from srcu_start_gp()
> > srcu: No need to advance/accelerate if no callback enqueued
> > srcu: Explain why callbacks invocations can't run concurrently
> >
> >
> > kernel/rcu/srcutree.c | 55 ++++++++++++++++++++++++++++++++++++---------------
> > 1 file changed, 39 insertions(+), 16 deletions(-)