From owner-freebsd-geom@FreeBSD.ORG  Tue Sep 25 19:37:27 2012
Return-Path: <owner-freebsd-geom@FreeBSD.ORG>
Delivered-To: geom@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34])
	by hub.freebsd.org (Postfix) with ESMTP id 626F5106564A;
	Tue, 25 Sep 2012 19:37:27 +0000 (UTC) (envelope-from jhb@freebsd.org)
Received: from bigwig.baldwin.cx (bigknife-pt.tunnel.tserv9.chi1.ipv6.he.net
	[IPv6:2001:470:1f10:75::2])
	by mx1.freebsd.org (Postfix) with ESMTP id 360728FC18;
	Tue, 25 Sep 2012 19:37:27 +0000 (UTC)
Received: from jhbbsd.localnet (unknown [209.249.190.124])
	by bigwig.baldwin.cx (Postfix) with ESMTPSA id 39C9AB944;
	Tue, 25 Sep 2012 15:37:26 -0400 (EDT)
From: John Baldwin <jhb@freebsd.org>
To: freebsd-ia64@freebsd.org,
 Paul Procacci <pprocacci@gmail.com>
Date: Tue, 25 Sep 2012 14:37:30 -0400
User-Agent: KMail/1.13.5 (FreeBSD/8.2-CBSD-20110714-p17; KDE/4.5.5; amd64; ; )
References: <201209251720.q8PHKE7T072562@freefall.freebsd.org>
In-Reply-To: <201209251720.q8PHKE7T072562@freefall.freebsd.org>
MIME-Version: 1.0
Content-Type: Text/Plain;
  charset="iso-8859-15"
Content-Transfer-Encoding: 7bit
Message-Id: <201209251437.30766.jhb@freebsd.org>
X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.2.7
	(bigwig.baldwin.cx); Tue, 25 Sep 2012 15:37:26 -0400 (EDT)
Cc: geom@freebsd.org
Subject: Re: ia64/171814: [panic] bioq_init or bioq_remove (unsure which)
X-BeenThere: freebsd-geom@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: GEOM-specific discussions and implementations
	<freebsd-geom.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-geom>,
	<mailto:freebsd-geom-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-geom>
List-Post: <mailto:freebsd-geom@freebsd.org>
List-Help: <mailto:freebsd-geom-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-geom>,
	<mailto:freebsd-geom-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Tue, 25 Sep 2012 19:37:27 -0000

On Tuesday, September 25, 2012 1:20:14 pm Paul Procacci wrote:
> The following reply was made to PR ia64/171814; it has been noted by GNATS.
> 
> From: Paul Procacci <pprocacci@gmail.com>
> To: John Baldwin <jhb@freebsd.org>
> Cc: freebsd-ia64@freebsd.org, freebsd-gnats-submit@freebsd.org
> Subject: Re: ia64/171814: [panic] bioq_init or bioq_remove (unsure which)
> Date: Tue, 25 Sep 2012 12:11:17 -0500
> 
>  --047d7b66f839532c0a04ca89cbf7
>  Content-Type: text/plain; charset=ISO-8859-1
>  
>  Thanks John for your response.
>  
>  Here is the output provided what you had explained to do:
>  
>  
>  0xffffffff80865023 is in devstat_remove_entry
>  (/usr/src/sys/kern/subr_devstat.c:193).
>  188
>  189             /* Remove this entry from the devstat queue */
>  190             atomic_add_acq_int(&ds->sequence1, 1);
>  191             if (ds->id == NULL) {
>  192                     devstat_num_devs--;
>  193                     STAILQ_REMOVE(devstat_head, ds, devstat, 
dev_links);
>  194             }
>  195             devstat_free(ds);
>  196             devstat_generation++;
>  197             mtx_unlock(&devstat_mutex);

I think the devstat entry must have been destroyed twice somehow.

Earlier in geom_subr.c the devstat entry is created with a unit of -1:

struct g_consumer *
g_new_consumer(struct g_geom *gp)
{
	...
	cp->stat = devstat_new_entry(cp, -1, 0, DEVSTAT_ALL_SUPPORTED,
	    DEVSTAT_TYPE_DIRECT, DEVSTAT_PRIORITY_MAX);
}

That should result in devstat_new_entry() setting ds->id to 'cp' (which is 
clearly not NULL), so it shouldn't even attempt the STAILQ_REMOVE(), but that 
is where it appears to have faulted.

-- 
John Baldwin