linux-kernel - Re: [PATCH] sched/isolation: reconcile rcu_nocbs= and nohz

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Message-ID: <YJ0X6MciAc36TMJc@gmail.com>
Date:   Thu, 13 May 2021 14:13:28 +0200
From:   Ingo Molnar <mingo@...nel.org>
To:     "Paul E. McKenney" <paulmck@...nel.org>
Cc:     Paul Gortmaker <paul.gortmaker@...driver.com>,
        linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Frederic Weisbecker <frederic@...nel.org>
Subject: Re: [PATCH] sched/isolation: reconcile rcu_nocbs= and nohz_full=


* Paul E. McKenney <paulmck@...nel.org> wrote:

> On Mon, Apr 19, 2021 at 12:26:59AM -0400, Paul Gortmaker wrote:
> > We have a mismatch between RCU and isolation -- in relation to what is
> > considered the maximum valid CPU number.
> > 
> > This matters because nohz_full= and rcu_nocbs= are joined at the hip; in
> > fact the former will enforce the latter.  So we don't want a CPU mask to
> > be valid for one and denied for the other.
> > 
> > The difference 1st appeared as of v4.15; further details are below.
> 
> I pulled this into -rcu for testing and further review.
> 
> If it should instead go through some other tree:
> 
> Acked-by: Paul E. McKenney <paulmck@...nel.org>

Thanks - added this fix to tip:sched/core.

Thanks,

	Ingo