From: Ingo Molnar <mingo@kernel.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
"Paul E. McKenney" <paulmck@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [GIT PULL] RCU changes for v5.10
Date: Mon, 19 Oct 2020 09:31:43 +0200 [thread overview]
Message-ID: <20201019073143.GA3785787@gmail.com> (raw)
In-Reply-To: <CAHk-=whE1rajA5Kzqey802zwv-82yrK5qc=nR3xRo5f38t-K8A@mail.gmail.com>
* Linus Torvalds <torvalds@linux-foundation.org> wrote:
> On Mon, Oct 12, 2020 at 7:14 AM Ingo Molnar <mingo@kernel.org> wrote:
> >
> > Please pull the latest core/rcu git tree from:
> >
> > git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git core-rcu-2020-10-12
>
> I've pulled everything but that last merge and the PREEMPT_COUNT
> stuff that came with it.
>
> When Paul asked whether it was ok for RCU to use preempt_count() and
> I answered in the affirmative, I didn't mean it in the sense of "RCU
> wants to force it on everybody else too".
>
> I'm pretty convinced that the proper fix is to simply make sure that
> rcu_free() and friends aren't run under any raw spinlocks. So even
> if the cost of preempt-count isn't that noticeable, there just isn't
> a reason for RCU to say "screw everybody else, I want this" when
> there are other alternatives.
That's certainly true - thanks for catching this & sorting it out from
the bigger pull request!
Thanks,
Ingo
prev parent reply other threads:[~2020-10-19 7:31 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-12 14:14 [GIT PULL] RCU changes for v5.10 Ingo Molnar
2020-10-12 20:25 ` Linus Torvalds
2020-10-12 21:44 ` Paul E. McKenney
2020-10-12 21:59 ` Linus Torvalds
2020-10-12 23:54 ` Paul E. McKenney
2020-10-13 0:14 ` Linus Torvalds
2020-10-13 2:41 ` Paul E. McKenney
2020-10-13 7:32 ` Ingo Molnar
2020-10-13 9:16 ` Thomas Gleixner
2020-10-18 21:39 ` Linus Torvalds
2020-10-19 3:24 ` Paul E. McKenney
2020-10-19 16:51 ` Linus Torvalds
2020-10-19 7:31 ` Ingo Molnar [this message]
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