linux-kernel - [PATCH 0/2] sched/nohz: disallow non-existent cores from nohz-full

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Message-ID: <20211206145950.10927-1-paul.gortmaker@windriver.com>
Date:   Mon, 6 Dec 2021 09:59:48 -0500
From:   Paul Gortmaker <paul.gortmaker@...driver.com>
To:     <linux-kernel@...r.kernel.org>
CC:     Paul Gortmaker <paul.gortmaker@...driver.com>,
        Frederic Weisbecker <fweisbec@...il.com>,
        Ingo Molnar <mingo@...nel.org>,
        Nicholas Piggin <npiggin@...il.com>,
        "Paul E . McKenney" <paulmck@...nel.org>,
        "Thomas Gleixner" <tglx@...utronix.de>
Subject: [PATCH 0/2] sched/nohz: disallow non-existent cores from nohz-full

A couple months back I sent a fix to reconcile rcu_nocbs= input
restrictions with nohz_full= input restrictions; with the latter being
more restrictive than the former.

However, in relaxing the nohz_full restrictions, I made it possible to
boot with a nohz_full= parameter that contains nothing but nonexistent
and not-possible cores - which will trigger a WARN.

This fixes the original reconcile commit by explicitly coding our
allowed values just like RCU does, and changes the WARN_ON to a
WARN_ON_ONCE, since it needlessly rendered the machine unusable.

---

Cc: Frederic Weisbecker <fweisbec@...il.com>
Cc: Ingo Molnar <mingo@...nel.org>
Cc: Nicholas Piggin <npiggin@...il.com>
Cc: Paul E. McKenney <paulmck@...nel.org>
Cc: Thomas Gleixner <tglx@...utronix.de>

Paul Gortmaker (2):
  sched/isolation: really align nohz_full with rcu_nocbs
  tick/nohz: WARN_ON --> WARN_ON_ONCE to prevent console saturation

 kernel/sched/isolation.c | 12 ++++++++++++
 kernel/time/tick-sched.c |  2 +-
 2 files changed, 13 insertions(+), 1 deletion(-)

-- 
2.17.1