linux-kernel - Re: [PATCH] rcu/kvfree: Invoke debug_rcu_bhead_unqueue() with check bnode->snap is done

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Message-ID: <bb56bb43-fc3e-42fd-9bdb-78e70a400daf@paulmck-laptop>
Date:   Wed, 5 Apr 2023 12:04:03 -0700
From:   "Paul E. McKenney" <paulmck@...nel.org>
To:     Uladzislau Rezki <urezki@...il.com>
Cc:     Zqiang <qiang1.zhang@...el.com>, frederic@...nel.org,
        joel@...lfernandes.org, qiang.zhang1211@...il.com,
        rcu@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] rcu/kvfree: Invoke debug_rcu_bhead_unqueue() with check
 bnode->snap is done

On Wed, Apr 05, 2023 at 04:45:27PM +0200, Uladzislau Rezki wrote:
> On Wed, Apr 05, 2023 at 10:13:59AM +0800, Zqiang wrote:
> > This commit make debug_rcu_bhead_unqueue() be invoked with check
> > the bnode structure's->snap is done in kvfree_rcu_bulk().
> > 
> > Signed-off-by: Zqiang <qiang1.zhang@...el.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 3461fc2640b9..17b5d115aec1 100644
> > --- a/kernel/rcu/tree.c
> > +++ b/kernel/rcu/tree.c
> > @@ -2943,8 +2943,8 @@ kvfree_rcu_bulk(struct kfree_rcu_cpu *krcp,
> >  	unsigned long flags;
> >  	int i;
> >  
> > -	debug_rcu_bhead_unqueue(bnode);
> >  	if (!WARN_ON_ONCE(!poll_state_synchronize_rcu_full(&bnode->gp_snap))) {
> > +		debug_rcu_bhead_unqueue(bnode);
> >  		rcu_lock_acquire(&rcu_callback_map);
> >  		if (idx == 0) { // kmalloc() / kfree().
> >  			trace_rcu_invoke_kfree_bulk_callback(
> > -- 
> > 2.32.0
> >
> Since we leak, looks like correct to me:
> 
> Reviewed-by: Uladzislau Rezki (Sony) <urezki@...il.com>

Queued for v6.5, thank you both!

							Thanx, Paul