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Message-ID: <6599ad830707170018p180cb7dfr53e609fd0b186e30@mail.gmail.com>
Date: Tue, 17 Jul 2007 00:18:33 -0700
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To: balbir@linux.vnet.ibm.com
Subject: Re: Containers: css_put() dilemma
Cc: "Pavel Emelianov" <xemul@sw.ru>,
       "linux kernel mailing list" <linux-kernel@vger.kernel.org>,
       "Paul Jackson" <pj@sgi.com>,
       "Linux Containers" <containers@lists.osdl.org>,
       "Andrew Morton" <akpm@linux-foundation.org>, dhaval@linux.vnet.ibm.com
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On 7/17/07, Balbir Singh <balbir@linux.vnet.ibm.com> wrote:
> >
> > >                mutex_lock(&container_mutex);
> > >                set_bit(CONT_RELEASABLE, &cont->flags);
> > >-               if (atomic_dec_and_test(&css->refcnt)) {
> > >-                       check_for_release(cont);
> > >-               }
> > >+               check_for_release(cont);
> > >                mutex_unlock(&container_mutex);
> > >

I think that this isn't safe as it stands, without a synchronize_rcu()
in container_diput() prior to the kfree(). Also, it will break if
anyone tries to use a release agent on a hierarchy that has your
memory controller bound to it.

Paul