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Message-ID: <1479163571.8455.83.camel@edumazet-glaptop3.roam.corp.google.com>
Subject: Re: Long delays creating a netns after deleting one (possibly RCU
 related)
From: Eric Dumazet <eric.dumazet@gmail.com>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
        Cong Wang <xiyou.wangcong@gmail.com>,
        Rolf Neugebauer <rolf.neugebauer@docker.com>,
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        Linux Kernel Network Developers <netdev@vger.kernel.org>,
        Justin Cormack <justin.cormack@docker.com>,
        Ian Campbell <ian.campbell@docker.com>,
        Eric Dumazet <edumazet@google.com>
Date: Mon, 14 Nov 2016 14:46:11 -0800
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On Mon, 2016-11-14 at 16:12 -0600, Eric W. Biederman wrote:

> synchronize_rcu_expidited is not enough if you have multiple network
> devices in play.
> 
> Looking at the code it comes down to this commit, and it appears there
> is a promise add rcu grace period combining by Eric Dumazet.
> 
> Eric since people are hitting noticable stalls because of the rcu grace
> period taking a long time do you think you could look at this code path
> a bit more?
> 
> commit 93d05d4a320cb16712bb3d57a9658f395d8cecb9
> Author: Eric Dumazet <edumazet@google.com>
> Date:   Wed Nov 18 06:31:03 2015 -0800

Absolutely, I will take a loop asap.

Thanks Eric.