Date: Fri, 10 Jun 2011 21:35:08 +0200 From: "K. Macy" <kmacy@freebsd.org> To: gibbs@freebsd.org Cc: fs@freebsd.org Subject: Re: Drop of spa_namespace lock in vdev_geom.c Message-ID: <BANLkTimUNQg_9Y94FTZnijOU%2Bp=QK3JV3A@mail.gmail.com> In-Reply-To: <4DF25544.3020301@FreeBSD.org> References: <4DF25544.3020301@FreeBSD.org>
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On Fri, Jun 10, 2011 at 7:32 PM, Justin T. Gibbs <gibbs@freebsd.org> wrote: > Dropping and reacquiring the spa_namespace lock in vdev_geom_open() > creates a lock order reversal with the spa_config locks. =A0As the > spa_config locks are not standard mutexes, witness will not warn > about this issue. The real problem is that WITNESS is disabled on the sx locks used for mutex compatibility in ZFS. This questionable decision has made debugging deadlocks quite painful on a number of occasions. I think this choice should be revisited and perhaps special workaround shims added for cases where cv_wait is called. -Kip
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