>
> On Tue, Mar 12, 2024 at 07:35:24PM +0800, Zqiang wrote:
> > The rcu_tasks_percpu structure's->lazy_timer is queued only when
> > the rcu_tasks structure's->lazy_jiffies is not equal to zero in
> > call_rcu_tasks_generic(), if the lazy_timer callback is invoked,
> > that means the lazy_jiffes is not equal to zero, this commit
> > therefore remove lazy_jiffies check in call_rcu_tasks_generic_timer().
> >
> > Signed-off-by: Zqiang <qiang.zhang1211@xxxxxxxxx>
> > ---
> > kernel/rcu/tasks.h | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h
> > index b1254cf3c210..439e0b9a2656 100644
> > --- a/kernel/rcu/tasks.h
> > +++ b/kernel/rcu/tasks.h
> > @@ -299,7 +299,7 @@ static void call_rcu_tasks_generic_timer(struct timer_list *tlp)
> >
> > rtp = rtpcp->rtpp;
> > raw_spin_lock_irqsave_rcu_node(rtpcp, flags);
> > - if (!rcu_segcblist_empty(&rtpcp->cblist) && rtp->lazy_jiffies) {
> > + if (!rcu_segcblist_empty(&rtpcp->cblist)) {
>
> Good eyes!
>
> But did you test with something like a WARN_ON_ONCE(rtp->lazy_jiffies)?
Hi, Paul
+ if (!rcu_segcblist_empty(&rtpcp->cblist) &&
!WARN_ON_ONCE(!rtp->lazy_jiffies))
I've done tests like this:
1. runqemu nographic kvm slirp qemuparams="-smp 4 -m 2048M -drive
file=$PWD/share.img,if=virtio"
bootparams="rcupdate.rcu_tasks_trace_lazy_ms=0" -d
2. insmod torture.ko
insmod rcutorture.ko torture_type=tasks-tracing fwd_progress=4
3. bpftrace -e 't:timer:timer_expire_entry /args->function ==
kaddr("call_rcu_tasks_generic_timer")/
{
printf("comm:%s,cpu:%d,stack:%s,func:%s\n", comm, cpu, kstack,
ksym(args->function)); }'
The call_rcu_tasks_generic_timer() has never been executed.
Thanks
Zqiang
>
> Thanx, Paul
>
> > if (!rtpcp->urgent_gp)
> > rtpcp->urgent_gp = 1;
> > needwake = true;
> > --
> > 2.17.1
> >
