linux-kernel - Re: [PATCH] rcu: Stop shrinker loop

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Message-ID: <20200604183927.GA26933@pc636>
Date:   Thu, 4 Jun 2020 20:39:27 +0200
From:   Uladzislau Rezki <urezki@...il.com>
To:     "Paul E. McKenney" <paulmck@...nel.org>
Cc:     Uladzislau Rezki <urezki@...il.com>,
        Peter Enderborg <peter.enderborg@...y.com>,
        Josh Triplett <josh@...htriplett.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Lai Jiangshan <jiangshanlai@...il.com>,
        Joel Fernandes <joel@...lfernandes.org>, rcu@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] rcu: Stop shrinker loop

> On Thu, Jun 04, 2020 at 03:42:55PM +0200, Uladzislau Rezki wrote:
> > On Thu, Jun 04, 2020 at 12:23:20PM +0200, Peter Enderborg wrote:
> > > The count and scan can be separated in time. It is a fair chance
> > > that all work is already done when the scan starts. It
> > > then might retry. This is can be avoided with returning SHRINK_STOP.
> > > 
> > > Signed-off-by: Peter Enderborg <peter.enderborg@...y.com>
> > > ---
> > >  kernel/rcu/tree.c | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > > 
> > > diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
> > > index c716eadc7617..8b36c6b2887d 100644
> > > --- a/kernel/rcu/tree.c
> > > +++ b/kernel/rcu/tree.c
> > > @@ -3310,7 +3310,7 @@ kfree_rcu_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
> > >  			break;
> > >  	}
> > >  
> > > -	return freed;
> > > +	return freed == 0 ? SHRINK_STOP : freed;
> > >  }
> > >  
> > The loop will be stopped anyway sooner or later, but sooner is better :)
> > To me that change makes sense.
> > 
> > Reviewed-by: Uladzislau Rezki (Sony) <urezki@...il.com>
> 
> Queued, thank you both!
> 
Thank you, Paul!

--
Vlad Rezki