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From: Uladzislau Rezki <urezki@gmail.com>
To: Joel Fernandes <joel@joelfernandes.org>
Cc: "Uladzislau Rezki (Sony)" <urezki@gmail.com>,
	LKML <linux-kernel@vger.kernel.org>,
	"Paul E . McKenney" <paulmck@kernel.org>,
	RCU <rcu@vger.kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	Oleksiy Avramchenko <oleksiy.avramchenko@sonymobile.com>
Subject: Re: [PATCH 6/7] rcu/tiny: support reclaim for head-less object
Date: Mon, 30 Mar 2020 16:42:27 +0200
Message-ID: <20200330144227.GA16651@pc636> (raw)
In-Reply-To: <20200330005637.GA138004@google.com>

> Hmm, Ok. So on -tiny, if there's any allocation failure ever, we immediately
> revert to call_rcu(). I guess we could also create a regular (non-array)
> queue for objects with an rcu_head and queue it on that (since it does not
> need allocation) in case of array allocation failure, however that may not be
> worth it. So this LGTM. Thanks!
> For entire series:
> Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
> (I will submit a follow-up to fix the tagging, please let me submit Vlad's
> entire series with some patches on top -- I also did a bit of wordsmithing in
> the commit messages of this series).
Thank you, Joel, for your review and help!

> Loved the might_sleep() idea btw, I suppose if atomic context wants to do
> kvfree_rcu(), then we could also have kfree_rcu() defer the kvfree_rcu() to
> execute from a workqueue. Thoughts? We can then allow poor insomniacs from
> calling this API :)
Not sure if i understand you correctly. Could you please <snip> some code
for illustration?

As far as i understand, it should be done then synchronously. We can defer  
and queue some work to do it in worqueue context. But i am not sure how
to proccess next coming request, i.e. busy waiting until we manage to push
a new ptr. to free? But in that case it would not work if there is only
one CPU available.


Vlad Rezki

  reply index

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-23 11:36 [PATCH 0/7] Headless support in the kvfree_rcu() Uladzislau Rezki (Sony)
2020-03-23 11:36 ` [PATCH 1/7] rcu/tree: simplify KFREE_BULK_MAX_ENTR macro Uladzislau Rezki (Sony)
2020-03-23 11:36 ` [PATCH 2/7] rcu/tree: maintain separate array for vmalloc ptrs Uladzislau Rezki (Sony)
2020-03-23 11:36 ` [PATCH 3/7] rcu/tree: introduce expedited_drain flag Uladzislau Rezki (Sony)
2020-03-23 11:36 ` [PATCH 4/7] rcu/tree: support reclaim for head-less object Uladzislau Rezki (Sony)
2020-03-29 22:56   ` Joel Fernandes
2020-03-30 12:48     ` Uladzislau Rezki
2020-03-23 11:36 ` [PATCH 5/7] rcu/tiny: move kvfree_call_rcu() out of header Uladzislau Rezki (Sony)
2020-03-23 11:36 ` [PATCH 6/7] rcu/tiny: support reclaim for head-less object Uladzislau Rezki (Sony)
2020-03-30  0:56   ` Joel Fernandes
2020-03-30 14:42     ` Uladzislau Rezki [this message]
2020-03-23 11:36 ` [PATCH 7/7] rcu: support headless variant in the kvfree_rcu() Uladzislau Rezki (Sony)

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