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Date: Tue, 13 Jan 2009 19:05:35 -0800
Message-ID: <6599ad830901131905ie10e4bl5168ab7f337b27e1@mail.gmail.com>
Subject: Re: [RFC][PATCH 4/4] cgroup-memcg fix frequent EBUSY at rmdir
From: Paul Menage <menage@google.com>
To: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: "linux-mm@kvack.org" <linux-mm@kvack.org>,
       "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
       "balbir@linux.vnet.ibm.com" <balbir@linux.vnet.ibm.com>,
       "nishimura@mxp.nes.nec.co.jp" <nishimura@mxp.nes.nec.co.jp>,
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On Tue, Jan 13, 2009 at 7:00 PM, KAMEZAWA Hiroyuki
<kamezawa.hiroyu@jp.fujitsu.com> wrote:
>
> Hmm, add wait_queue to css and wake it up at css_put() ?
>
> like this ?
> ==
> __css_put()
> {
>        if (atomi_dec_return(&css->refcnt) == 1) {
>                if (notify_on_release(cgrp) {
>                        .....
>                }
>                if (someone_waiting_rmdir(css)) {
>                        wake_up_him().
>                }
>        }
> }

Yes, something like that. A system-wide wake queue is probably fine though.

> pre_destroy() is for that.  Now, If there are still references from "page"
> after pre_destroy(), it's bug.

OK.

Paul