linux-kernel - Re: [PATCH 0/3] timers & RCU: Fix TREE03 stalls

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Date: Mon, 18 Dec 2023 17:40:42 -0800
From: "Paul E. McKenney" <paulmck@...nel.org>
To: Frederic Weisbecker <frederic@...nel.org>
Cc: LKML <linux-kernel@...r.kernel.org>, Boqun Feng <boqun.feng@...il.com>,
	Joel Fernandes <joel@...lfernandes.org>,
	Neeraj Upadhyay <neeraj.upadhyay@....com>,
	Uladzislau Rezki <urezki@...il.com>,
	Zqiang <qiang.zhang1211@...il.com>, rcu <rcu@...r.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Peter Zijlstra <peterz@...radead.org>
Subject: Re: [PATCH 0/3] timers & RCU: Fix TREE03 stalls

On Tue, Dec 19, 2023 at 12:19:13AM +0100, Frederic Weisbecker wrote:
> 5c0930ccaad5 ("hrtimers: Push pending hrtimers away from outgoing CPU earlier")
> has introduced an issue with RCU. This is a proposal to solve the
> situation after realizing that fixing that on the timers side wouldn't
> be pretty to say the least.
> 
> Oh and the last patch is absolutely irrelevant to the issue...

I pulled all three in and started testing.

That last one will need some careful review, but you knew that already.  ;-)

							Thanx, Paul

> Frederic Weisbecker (3):
>   hrtimer: Report offline hrtimer enqueue
>   rcu: Defer RCU kthreads wakeup when CPU is dying
>   rcu/exp: Remove full barrier upon main thread wakeup
> 
>  include/linux/hrtimer.h |  3 ++-
>  kernel/rcu/tree.c       | 34 +++++++++++++++++++++++++++++++++-
>  kernel/rcu/tree_exp.h   |  8 +++-----
>  kernel/time/hrtimer.c   |  3 +++
>  4 files changed, 41 insertions(+), 7 deletions(-)
> 
> -- 
> 2.42.1
>