linux-kernel - Re: [PATCH 0/5] srcu fixes

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Message-ID: <f214737a-6856-455f-ac86-9f7ec605b902@paulmck-laptop>
Date:   Tue, 3 Oct 2023 17:35:31 -0700
From:   "Paul E. McKenney" <paulmck@...nel.org>
To:     Frederic Weisbecker <frederic@...nel.org>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Yong He <zhuangel570@...il.com>,
        Neeraj upadhyay <neeraj.iitr10@...il.com>,
        Joel Fernandes <joel@...lfernandes.org>,
        Boqun Feng <boqun.feng@...il.com>,
        Uladzislau Rezki <urezki@...il.com>, RCU <rcu@...r.kernel.org>
Subject: Re: [PATCH 0/5] srcu fixes

On Wed, Oct 04, 2023 at 01:28:58AM +0200, Frederic Weisbecker wrote:
> Hi,
> 
> This contains a fix for "SRCU: kworker hung in synchronize_srcu":
> 
> 	http://lore.kernel.org/CANZk6aR+CqZaqmMWrC2eRRPY12qAZnDZLwLnHZbNi=xXMB401g@mail.gmail.com
> 
> And a few cleanups.
> 
> Passed 50 hours of SRCU-P and SRCU-N.
> 
> git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks.git
> 	srcu/fixes
> 
> HEAD: 7ea5adc5673b42ef06e811dca75e43d558cc87e0
> 
> Thanks,
> 	Frederic

Very good, and a big "Thank You!!!" to all of you!

I queued this series for testing purposes, and have started a bunch of
SRCU-P and SRCU-N tests on one set of systems, and a single SRCU-P and
SRCU-N on another system, but with both scenarios resized to 40 CPU each.

While that is in flight, a few questions:

o	Please check the Co-developed-by rules.  Last I knew, it was
	necessary to have a Signed-off-by after each Co-developed-by.

o	Is it possible to get a Tested-by from the original reporter?
	Or is this not reproducible?

o	Is it possible to convince rcutorture to find this sort of
	bug?  Seems like it should be, but easy to say...

o	Frederic, would you like to include this in your upcoming
	pull request?  Or does it need more time?

						Thanx, Paul

> ---
> 
> Frederic Weisbecker (5):
>       srcu: Fix callbacks acceleration mishandling
>       srcu: Only accelerate on enqueue time
>       srcu: Remove superfluous callbacks advancing from srcu_start_gp()
>       srcu: No need to advance/accelerate if no callback enqueued
>       srcu: Explain why callbacks invocations can't run concurrently
> 
> 
>  kernel/rcu/srcutree.c | 55 ++++++++++++++++++++++++++++++++++++---------------
>  1 file changed, 39 insertions(+), 16 deletions(-)