From: Linus Torvalds <torvalds@linux-foundation.org>
To: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: "Paul E. McKenney" <paulmck@linux.ibm.com>,
Peter Zijlstra <peterz@infradead.org>,
Linux List Kernel Mailing <linux-kernel@vger.kernel.org>,
Oleg Nesterov <oleg@redhat.com>,
"Eric W. Biederman" <ebiederm@xmission.com>,
Russell King - ARM Linux admin <linux@armlinux.org.uk>,
Chris Metcalf <cmetcalf@ezchip.com>,
Christoph Lameter <cl@linux.com>, Kirill Tkhai <tkhai@yandex.ru>,
Mike Galbraith <efault@gmx.de>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@kernel.org>
Subject: Re: [RFC PATCH 1/2] Fix: sched/membarrier: p->mm->membarrier_state racy load
Date: Tue, 3 Sep 2019 13:27:23 -0700 [thread overview]
Message-ID: <CAHk-=wg61zhuzhnrh_t=cAhgm+adNfsnS0A_cD=TOQAriHNDew@mail.gmail.com> (raw)
In-Reply-To: <20190903201135.1494-1-mathieu.desnoyers@efficios.com>
On Tue, Sep 3, 2019 at 1:11 PM Mathieu Desnoyers
<mathieu.desnoyers@efficios.com> wrote:
>
> + cpus_read_lock();
> + for_each_online_cpu(cpu) {
This would likely be better off using mm_cpumask(mm) instead of all
online CPU's.
Plus doing the rcu_read_lock() inside the loop seems pointless. Even
with a lot of cores, it's not going to loop _that_ many times for RCU
latency to be an issue.
Linus
next prev parent reply other threads:[~2019-09-03 20:27 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-03 20:11 [RFC PATCH 1/2] Fix: sched/membarrier: p->mm->membarrier_state racy load Mathieu Desnoyers
2019-09-03 20:11 ` [RFC PATCH 2/2] Fix: sched/membarrier: private expedited registration check Mathieu Desnoyers
2019-09-03 20:24 ` [RFC PATCH 1/2] Fix: sched/membarrier: p->mm->membarrier_state racy load Peter Zijlstra
2019-09-03 20:36 ` Linus Torvalds
2019-09-04 15:19 ` Mathieu Desnoyers
2019-09-04 16:09 ` Peter Zijlstra
2019-09-04 17:12 ` Mathieu Desnoyers
2019-09-04 18:26 ` Peter Zijlstra
2019-09-06 0:51 ` Mathieu Desnoyers
2019-09-03 20:41 ` Mathieu Desnoyers
2019-09-04 11:28 ` Peter Zijlstra
2019-09-04 11:49 ` Peter Zijlstra
2019-09-04 15:26 ` Mathieu Desnoyers
2019-09-04 12:03 ` Oleg Nesterov
2019-09-04 12:43 ` Peter Zijlstra
2019-09-04 13:17 ` Oleg Nesterov
2019-09-03 20:27 ` Linus Torvalds [this message]
2019-09-03 20:53 ` Mathieu Desnoyers
2019-09-04 10:53 ` Oleg Nesterov
2019-09-04 11:39 ` Peter Zijlstra
2019-09-04 15:24 ` Mathieu Desnoyers
2019-09-04 11:11 ` Oleg Nesterov
2019-09-04 16:11 ` Mathieu Desnoyers
2019-09-08 13:46 ` Mathieu Desnoyers
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