Re: [PATCH] kprobes: Fix to delay the kprobes jump optimization

From: Paul E. McKenney
Date: Fri Feb 19 2021 - 16:23:19 EST


On Fri, Feb 19, 2021 at 03:02:31PM -0500, Steven Rostedt wrote:
> On Fri, 19 Feb 2021 10:33:36 -0800
> "Paul E. McKenney" <paulmck@xxxxxxxxxx> wrote:
>
> > commit 4f659bf04fc4610523544493d6db92fc8670b086
> > Author: Paul E. McKenney <paulmck@xxxxxxxxxx>
> > Date: Fri Feb 12 16:20:40 2021 -0800
> >
> > softirq: Don't try waking ksoftirqd before it has been spawned
> >
> > If there is heavy softirq activity, the softirq system will attempt
> > to awaken ksoftirqd and will stop the traditional back-of-interrupt
> > softirq processing. This is all well and good, but only if the
> > ksoftirqd kthreads already exist, which is not the case during early
> > boot, in which case the system hangs.
> >
> > One reproducer is as follows:
> >
> > tools/testing/selftests/rcutorture/bin/kvm.sh --allcpus --duration 2 --configs "TREE03" --kconfig "CONFIG_DEBUG_LOCK_ALLOC=y CONFIG_PROVE_LOCKING=y" --bootargs "threadirqs=1" --trust-make
> >
> > This commit therefore adds a couple of existence checks for ksoftirqd
> > and forces back-of-interrupt softirq processing when ksoftirqd does not
> > yet exist. With this change, the above test passes.
> >
> > Reported-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
> > Reported-by: Uladzislau Rezki <urezki@xxxxxxxxx>
> > Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
>
> Hmm, I wonder if this is what patchwork picked up regarding the
> reported-by.
>
> And I checked, it did not add the "Signed-off-by" from you to Masami's
> patch ;-)
>
> The dangers of posting patches in threads of other patches :-/

Glad I asked, then! ;-)

Thanx, Paul