linux-kernel - [PATCH 0/3] sched: migrate_disable() vs per-CPU access safety checks

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Date:   Wed, 21 Jul 2021 12:51:15 +0100
From:   Valentin Schneider <valentin.schneider@....com>
To:     linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-rt-users@...r.kernel.org
Cc:     Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>, Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Steven Rostedt <rostedt@...dmis.org>,
        Daniel Bristot de Oliveira <bristot@...hat.com>,
        "Paul E. McKenney" <paulmck@...nel.org>,
        Josh Triplett <josh@...htriplett.org>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Lai Jiangshan <jiangshanlai@...il.com>,
        Joel Fernandes <joel@...lfernandes.org>,
        Anshuman Khandual <anshuman.khandual@....com>,
        Vincenzo Frascino <vincenzo.frascino@....com>,
        Steven Price <steven.price@....com>,
        Ard Biesheuvel <ardb@...nel.org>
Subject: [PATCH 0/3] sched: migrate_disable() vs per-CPU access safety checks

Hi folks,

I've hit a few warnings when taking v5.13-rt1 out for a spin on my arm64
Juno. Those are due to regions that become preemptible under PREEMPT_RT, but
remain safe wrt per-CPU accesses due to migrate_disable() + a sleepable lock.

This adds a helper that looks at not just preemptability but also affinity and
migrate disable, and plasters the warning sites.

Cheers,
Valentin

Valentin Schneider (3):
  sched: Introduce is_pcpu_safe()
  rcu/nocb: Check for migratability rather than pure preemptability
  arm64: mm: Make arch_faults_on_old_pte() check for migratability

 arch/arm64/include/asm/pgtable.h |  2 +-
 include/linux/sched.h            | 10 ++++++++++
 kernel/rcu/tree_plugin.h         |  3 +--
 3 files changed, 12 insertions(+), 3 deletions(-)

--
2.25.1