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From: Tejun Heo <tj@kernel.org>
To: "jianchao.wang" <jianchao.w.wang@oracle.com>
Cc: Ming Lei <ming.lei@redhat.com>,
	linux-kernel@vger.kernel.org,
	Kent Overstreet <kent.overstreet@gmail.com>,
	linux-block@vger.kernel.org
Subject: Re: [PATCH] percpu-refcount: relax limit on percpu_ref_reinit()
Date: Tue, 11 Sep 2018 06:44:04 -0700	[thread overview]
Message-ID: <20180911134404.GF1100574@devbig004.ftw2.facebook.com> (raw)
In-Reply-To: <771fa1eb-85d3-2ff2-6070-207874da85b6@oracle.com>

Hello,

On Tue, Sep 11, 2018 at 12:40:36PM +0800, jianchao.wang wrote:
> (long)(sum (every cpu's refcounter)) + atomic refcounter
> 
> and when switch to atomic mode, there could be value left in atomic refcounter.
> then the unsigned long percpu refcounter cound be decreased from 0.

It can always do that.  Imagine a task getting a ref on one cpu,
migrating and putting it on another.  The only thing which matters is
that the sum of everything adds upto what it should be.

Thanks.

-- 
tejun

  parent reply	other threads:[~2018-09-11 13:44 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-09-09 12:58 Ming Lei
2018-09-09 18:46 ` Bart Van Assche
2018-09-09 23:59   ` Ming Lei
2018-09-10  1:40 ` jianchao.wang
2018-09-10 16:11   ` Ming Lei
2018-09-11  1:48     ` jianchao.wang
2018-09-11  4:03       ` Ming Lei
2018-09-11  4:40         ` jianchao.wang
2018-09-11  8:20           ` Ming Lei
2018-09-11 14:22             ` jianchao.wang
2018-09-11 13:44           ` Tejun Heo [this message]
2018-09-11 14:13             ` jianchao.wang
2018-09-10  1:54 ` jianchao.wang
2018-09-10 16:49 ` Tejun Heo
2018-09-11  0:00   ` Ming Lei
2018-09-11 13:48     ` Tejun Heo
2018-09-11 15:45       ` Ming Lei
2018-09-11 15:49         ` Tejun Heo
2018-09-11 16:05           ` Ming Lei
2018-09-11 16:30             ` Tejun Heo
2018-09-11 16:34               ` Ming Lei
2018-09-11 16:38                 ` Tejun Heo
2018-09-12  1:52                   ` Ming Lei
2018-09-12 15:53                     ` Tejun Heo
2018-09-12 22:11                       ` Ming Lei
2018-09-18 12:49                         ` Tejun Heo
2018-09-19  2:51                           ` Ming Lei
2018-09-19 20:36                             ` Tejun Heo
2018-09-18  3:21 ` jianchao.wang
2018-09-18  7:34   ` Ming Lei

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