From: Mike Christie <michaelc@cs.wisc.edu>
To: Tao Ma <tao.ma@oracle.com>
Cc: open-iscsi@googlegroups.com, linux-kernel@vger.kernel.org
Subject: Re: lockdep warning for iscsi in 2.6.33-rc6
Date: Tue, 09 Feb 2010 13:30:33 -0600 [thread overview]
Message-ID: <4B71B7D9.9040501@cs.wisc.edu> (raw)
In-Reply-To: <4B7107CF.3060703@oracle.com>
On 02/09/2010 12:59 AM, Tao Ma wrote:
> Hi Mike,
> I meet with a lockdep warning for iscsi in 2.6.33-rc6.
> the lockdep is attached.
>
If the lockdep output is saying that there is a problem with the iscsi
host taking its mutex then the scsi host mutex, I think that might be a
mistake in the lockdep detection. We always take the iscsi host mutex
then take the scsi host mutex.
Could it get confused if we are scanning two hosts at the same time? If
it is just looking at if a lock is being taken then it would look like
host1 has its ihost->mutex and then took its shost->mutex, but then
host2 could start to get scanned at the same time, and it is going to
take its ihost->mutex. It would then look like we are trying to grab a
ihost->mutex while holding a shost->mutex. However, the mutexs are not
global and they are different instances of the mutex because each host
has its own.
If that is not the problem, maybe it has something to do with some sysfs
lock and ata doing scanning while iscsi is.
next prev parent reply other threads:[~2010-02-09 19:30 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-02-09 6:59 lockdep warning for iscsi in 2.6.33-rc6 Tao Ma
2010-02-09 19:30 ` Mike Christie [this message]
2010-02-10 0:42 ` Tao Ma
2010-02-12 17:21 ` Mike Christie
2010-02-11 20:08 ` Maciej Rutecki
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