linux-kernel - Re: [PATCH 2/2] rcu: Don't dump the stalled CPU on where RCU GP kthread last ran twice

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Message-ID: <CAEXW_YR_t-x-eYKLFmruOLqZv91oi=AJKEEeuqYosejjdscn1g@mail.gmail.com>
Date:   Mon, 10 Jul 2023 15:55:16 -0400
From:   Joel Fernandes <joel@...lfernandes.org>
To:     paulmck@...nel.org
Cc:     Zhen Lei <thunder.leizhen@...wei.com>,
        Frederic Weisbecker <frederic@...nel.org>,
        Neeraj Upadhyay <quic_neeraju@...cinc.com>,
        Josh Triplett <josh@...htriplett.org>,
        Boqun Feng <boqun.feng@...il.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Lai Jiangshan <jiangshanlai@...il.com>,
        Zqiang <qiang.zhang1211@...il.com>, rcu@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] rcu: Don't dump the stalled CPU on where RCU GP
 kthread last ran twice

On Mon, Jul 10, 2023 at 3:06 PM Paul E. McKenney <paulmck@...nel.org> wrote:
>
> On Wed, Jul 05, 2023 at 03:30:20PM +0800, Zhen Lei wrote:
> > The stacks of all stalled CPUs will be dumped. If the CPU on where RCU GP
> > kthread last ran is stalled, its stack does not need to be dumped again.
> >
> > Signed-off-by: Zhen Lei <thunder.leizhen@...wei.com>
>
> This one looks good.  Please feel free to rebase it before 1/2 and repost.

Just a small comment:
I wondered if this would make it harder to identify which stack among
the various CPU stacks corresponds to the one the GP kthread is
running on. However, this line does print the CPU number of the
thread, so it is perhaps not an issue:

                pr_err("%s kthread starved for %ld jiffies! g%ld f%#x
%s(%d) ->state=%#x ->cpu=%d\n",

Reviewed-by: Joel Fernandes (Google) <joel@...lfernandes.org>

Thanks.