Received-SPF: pass (google.com: domain of linux-kernel+bounces-25907-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:4601:e00::3 as permitted sender) client-ip=2604:1380:4601:e00::3;
From: Uladzislau Rezki <urezki@gmail.com>
Date: Mon, 15 Jan 2024 11:57:39 +0100
To: Z qiang <qiang.zhang1211@gmail.com>
Cc: Z qiang <qiang.zhang1211@gmail.com>,
	"Paul E . McKenney" <paulmck@kernel.org>, RCU <rcu@vger.kernel.org>,
	Neeraj upadhyay <Neeraj.Upadhyay@amd.com>,
	Boqun Feng <boqun.feng@gmail.com>, Hillf Danton <hdanton@sina.com>,
	Joel Fernandes <joel@joelfernandes.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Oleksiy Avramchenko <oleksiy.avramchenko@sony.com>,
	Frederic Weisbecker <frederic@kernel.org>
Subject: Re: [PATCH v4 4/4] rcu: Support direct wake-up of synchronize_rcu()
 users
Message-ID: <ZaUPo97uzZlGkNdY@pc636>
References: <20240104162510.72773-1-urezki@gmail.com>
 <20240104162510.72773-5-urezki@gmail.com>
 <CALm+0cUM=5bg0eKQ4D-mm7ZaAnQbf+2NjetUYnqHOLq5uR0w5g@mail.gmail.com>
 <ZaUNCJyYREsw7O3h@pc636>
Precedence: bulk
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <ZaUNCJyYREsw7O3h@pc636>

> Hello, Zqiang.
> 
> > >
> > >         // concurrent sr_normal_gp_cleanup work might observe this update.
> > >         smp_store_release(&rcu_state.srs_done_tail, wait_tail);
> > >         ASSERT_EXCLUSIVE_WRITER(rcu_state.srs_done_tail);
> > >
> > > -       if (wait_tail)
> > > +       if (wait_tail->next)
> > >                 queue_work(system_highpri_wq, &sr_normal_gp_cleanup);
> > >
> > 
> > I'm testing these patches :) , one question is as follows:
> > Can we use (WQ_MEM_RECLAIM | WQ_HIGHPR)type of workqueue to perform
> > wake-up actions? avoid kworker creation failure under memory pressure, causing
> > the wake-up action to be delayed.
> > 
> I do not have any objections in not doing that, so we can add.
> 
> Thank for testing this!
> 
I forgot to ask, is your testing simulates a low memory condition so
you see the failure you refer to? Or it is just a possible scenario?

Thanks!

--
Uladzislau Rezki