From: Uladzislau Rezki <urezki@gmail.com>
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Uladzislau Rezki <urezki@gmail.com>,
Joel Fernandes <joel@joelfernandes.org>,
LKML <linux-kernel@vger.kernel.org>, RCU <rcu@vger.kernel.org>,
linux-mm <linux-mm@kvack.org>,
"Paul E . McKenney" <paulmck@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
"Theodore Y . Ts'o" <tytso@mit.edu>,
Matthew Wilcox <willy@infradead.org>,
Oleksiy Avramchenko <oleksiy.avramchenko@sonymobile.com>
Subject: Re: [PATCH 1/1] rcu/tree: Drop the lock before entering to page allocator
Date: Thu, 16 Jul 2020 16:47:28 +0200 [thread overview]
Message-ID: <20200716144728.GA31046@pc636> (raw)
In-Reply-To: <20200716142537.ecp4icsq7kg6qhdx@linutronix.de>
On Thu, Jul 16, 2020 at 04:25:37PM +0200, Sebastian Andrzej Siewior wrote:
> On 2020-07-16 11:19:13 [+0200], Uladzislau Rezki wrote:
> > Sebastian, could you please confirm that if that patch that is in
> > question fixes it?
> >
> > It would be appreciated!
>
> So that preempt disable should in terms any warnings. However I don't
> think that it is strictly needed and from scheduling point of view you
> forbid a CPU migration which might be good otherwise.
>
Please elaborate your point regarding "i do not think it is strictly needed".
Actually i can rework the patch to remove even such preempt_enable/disable
to stay on the same CPU, but i do not see the point of doing it.
Do you see the point?
As for scheduling point of view. Well, there are many places when there
is a demand in memory or pages from atomic context. Also, getting a page
is not considered as a hot path in the kfree_rcu().
>
> Also if interrupts and everything is enabled then someone else might
> invoke kfree_rcu() from BH context for instance.
>
And what? What is a problem here, please elaborate if you see any
issues.
--
Vlad Rezki
next prev parent reply other threads:[~2020-07-16 14:47 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-15 18:35 [PATCH 1/1] rcu/tree: Drop the lock before entering to page allocator Uladzislau Rezki (Sony)
2020-07-15 18:56 ` Sebastian Andrzej Siewior
2020-07-15 19:02 ` Uladzislau Rezki
2020-07-15 19:32 ` Sebastian Andrzej Siewior
2020-07-15 19:36 ` Uladzislau Rezki
2020-07-15 22:14 ` Paul E. McKenney
2020-07-16 14:14 ` Sebastian Andrzej Siewior
2020-07-16 15:20 ` Paul E. McKenney
2020-07-16 15:36 ` Sebastian Andrzej Siewior
2020-07-16 16:36 ` Paul E. McKenney
2020-07-15 23:13 ` Joel Fernandes
2020-07-16 9:19 ` Uladzislau Rezki
2020-07-16 13:36 ` Joel Fernandes
2020-07-16 14:37 ` Uladzislau Rezki
2020-07-16 18:27 ` Joel Fernandes
2020-07-16 19:03 ` Uladzislau Rezki
2020-07-16 14:25 ` Sebastian Andrzej Siewior
2020-07-16 14:47 ` Uladzislau Rezki [this message]
2020-07-16 15:04 ` Sebastian Andrzej Siewior
2020-07-16 15:34 ` Uladzislau Rezki
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