linux-kernel - Re: Containers: css

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Message-Id: <20070717102327.dc402025.pj@sgi.com>
Date:	Tue, 17 Jul 2007 10:23:27 -0700
From:	Paul Jackson <pj@....com>
To:	"Paul (______) Menage" 
	<menage@...gle.com>
Cc:	balbir@...ux.vnet.ibm.com, dhaval@...ux.vnet.ibm.com, xemul@...ru,
	linux-kernel@...r.kernel.org, containers@...ts.osdl.org,
	akpm@...ux-foundation.org
Subject: Re: Containers: css_put() dilemma

> Because as soon as you do the atomic_dec_and_test() on css->refcnt and
> the refcnt hits zero, then theoretically someone other thread (that
> already holds container_mutex) could check that the refcount is zero
> and free the container structure.

Not just theory ... I've debugged crashes from live customer systems
that were basically this race.

-- 
                  I won't rest till it's the best ...
                  Programmer, Linux Scalability
                  Paul Jackson <pj@....com> 1.925.600.0401
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