On Thu, Nov 17, 2022 at 01:44:12PM -0800, Eric Dumazet wrote: > On Wed, Nov 16, 2022 at 7:16 PM Joel Fernandes (Google) > <joel@xxxxxxxxxxxxxxxxx> wrote: > > > > In a networking test on ChromeOS, we find that using the new CONFIG_RCU_LAZY > > causes a networking test to fail in the teardown phase. > > > > The failure happens during: ip netns del <name> > > > > Using ftrace, I found the callbacks it was queuing which this series fixes. Use > > call_rcu_flush() to revert to the old behavior. With that, the test passes. > > > > Signed-off-by: Joel Fernandes (Google) <joel@xxxxxxxxxxxxxxxxx> > > --- > > net/sched/sch_generic.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c > > index a9aadc4e6858..63fbf640d3b2 100644 > > --- a/net/sched/sch_generic.c > > +++ b/net/sched/sch_generic.c > > @@ -1067,7 +1067,7 @@ static void qdisc_destroy(struct Qdisc *qdisc) > > > > trace_qdisc_destroy(qdisc); > > > > - call_rcu(&qdisc->rcu, qdisc_free_cb); > > + call_rcu_flush(&qdisc->rcu, qdisc_free_cb); > > } > > I took a look at this one. > > qdisc_free_cb() is essentially freeing : Some per-cpu memory, and the > 'struct Qdisc' > > I do not see why we need to force a flush for this (small ?) piece of memory. Indeed! Just tested and dropping this one still makes the test pass. I believe this patch was papering over the issues fixed by the other patches, so it stuck. I will drop this one and move over to trying your suggestions for 2/3. Thanks for taking a look, - Joel
