linux-kernel - Re: [PATCH v2 8/8] rcu/kfree: Fix kfree_rcu_shrink

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Message-ID: <YroelcGVNhQj91ab@google.com>
Date:   Mon, 27 Jun 2022 21:18:13 +0000
From:   Joel Fernandes <joel@...lfernandes.org>
To:     "Paul E. McKenney" <paulmck@...nel.org>
Cc:     Uladzislau Rezki <urezki@...il.com>, rcu@...r.kernel.org,
        linux-kernel@...r.kernel.org, rushikesh.s.kadam@...el.com,
        neeraj.iitr10@...il.com, frederic@...nel.org, rostedt@...dmis.org,
        vineeth@...byteword.org
Subject: Re: [PATCH v2 8/8] rcu/kfree: Fix kfree_rcu_shrink_count() return
 value

On Mon, Jun 27, 2022 at 01:59:07PM -0700, Paul E. McKenney wrote:
> On Mon, Jun 27, 2022 at 08:56:43PM +0200, Uladzislau Rezki wrote:
> > > As per the comments in include/linux/shrinker.h, .count_objects callback
> > > should return the number of freeable items, but if there are no objects
> > > to free, SHRINK_EMPTY should be returned. The only time 0 is returned
> > > should be when we are unable to determine the number of objects, or the
> > > cache should be skipped for another reason.
> > > 
> > > Signed-off-by: Joel Fernandes (Google) <joel@...lfernandes.org>
> > > ---
> > >  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 711679d10cbb..935788e8d2d7 100644
> > > --- a/kernel/rcu/tree.c
> > > +++ b/kernel/rcu/tree.c
> > > @@ -3722,7 +3722,7 @@ kfree_rcu_shrink_count(struct shrinker *shrink, struct shrink_control *sc)
> > >  		atomic_set(&krcp->backoff_page_cache_fill, 1);
> > >  	}
> > >  
> > > -	return count;
> > > +	return count == 0 ? SHRINK_EMPTY : count;
> > >  }
> > >  
> > >  static unsigned long
> > > -- 
> > > 2.37.0.rc0.104.g0611611a94-goog
> > > 
> > Looks good to me!
> > 
> > Reviewed-by: Uladzislau Rezki (Sony) <urezki@...il.com>
> 
> Now that you mention it, this does look independent of the rest of
> the series.  I have pulled it in with Uladzislau's Reviewed-by.

Thanks Paul and Vlad!

Paul, apologies for being quiet. I have been working on the series and the
review comments carefully. I appreciate your help with this work.

thanks,

 - Joel