From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Valentin Schneider <valentin.schneider@arm.com>
Cc: linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linux-rt-users@vger.kernel.org,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>, Ingo Molnar <mingo@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
Steven Rostedt <rostedt@goodmis.org>,
Daniel Bristot de Oliveira <bristot@redhat.com>,
"Paul E. McKenney" <paulmck@kernel.org>,
Frederic Weisbecker <frederic@kernel.org>,
Josh Triplett <josh@joshtriplett.org>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Davidlohr Bueso <dave@stgolabs.net>,
Lai Jiangshan <jiangshanlai@gmail.com>,
Joel Fernandes <joel@joelfernandes.org>,
Anshuman Khandual <anshuman.khandual@arm.com>,
Vincenzo Frascino <vincenzo.frascino@arm.com>,
Steven Price <steven.price@arm.com>,
Ard Biesheuvel <ardb@kernel.org>,
Boqun Feng <boqun.feng@gmail.com>, Mike Galbraith <efault@gmx.de>
Subject: Re: [PATCH v4] arm64: mm: Make arch_faults_on_old_pte() check for migratability
Date: Fri, 4 Feb 2022 10:29:28 +0100 [thread overview]
Message-ID: <Yfzx+P3jUXA0Z/Y7@linutronix.de> (raw)
In-Reply-To: <20220127192437.1192957-1-valentin.schneider@arm.com>
On 2022-01-27 19:24:37 [+0000], Valentin Schneider wrote:
> arch_faults_on_old_pte() relies on the calling context being
> non-preemptible. CONFIG_PREEMPT_RT turns the PTE lock into a sleepable
> spinlock, which doesn't disable preemption once acquired, triggering the
> warning in arch_faults_on_old_pte().
>
> It does however disable migration, ensuring the task remains on the same
> CPU during the entirety of the critical section, making the read of
> cpu_has_hw_af() safe and stable.
>
> Make arch_faults_on_old_pte() check cant_migrate() instead of preemptible().
>
> Suggested-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
> Link: https://lore.kernel.org/r/20210811201354.1976839-5-valentin.schneider@arm.com
Let me pick that up so I can drop the other two. I hope the ARM64 folks
follow my lead ;)
Acked-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Sebastian
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next prev parent reply other threads:[~2022-02-04 9:30 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-27 19:24 [PATCH v4] arm64: mm: Make arch_faults_on_old_pte() check for migratability Valentin Schneider
2022-02-04 9:29 ` Sebastian Andrzej Siewior [this message]
2022-02-04 18:55 ` Catalin Marinas
2022-02-04 19:09 ` Sebastian Andrzej Siewior
2022-02-15 15:37 ` Will Deacon
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