From: Neil Brown <neilb@suse.de>
To: Jon Nelson <jnelson-linux-raid@jamponi.net>
Cc: linux-raid@vger.kernel.org
Subject: Re: mdadm --stop goes off and never comes back?
Date: Sat, 22 Dec 2007 22:58:57 +1100 [thread overview]
Message-ID: <18284.64513.783072.915203@notabene.brown> (raw)
In-Reply-To: message from Jon Nelson on Wednesday December 19
On Wednesday December 19, jnelson-linux-raid@jamponi.net wrote:
> On 12/19/07, Jon Nelson <jnelson-linux-raid@jamponi.net> wrote:
> > On 12/19/07, Neil Brown <neilb@suse.de> wrote:
> > > On Tuesday December 18, jnelson-linux-raid@jamponi.net wrote:
> > > >
> > > > I tried to stop the array:
> > > >
> > > > mdadm --stop /dev/md2
> > > >
> > > > and mdadm never came back. It's off in the kernel somewhere. :-(
Looking at your stack traces, you have the "mdadm -S" holding
an md lock and trying to get a sysfs lock as part of tearing down the
array, and 'hald' is trying to read some attribute in
/sys/block/md....
and is holding the sysfs lock and trying to get the md lock.
A classic AB-BA deadlock.
>
> NOTE: kernel is stock openSUSE 10.3 kernel, x86_64, 2.6.22.13-0.3-default.
>
It is fixed in mainline with some substantial changes to sysfs.
I don't imagine they are likely to get back ported to openSUSE, but
you could try logging a bugzilla if you like.
The 'hald' process is interruptible and killing it would release the
deadlock.
I suspect you have to be fairly unlucky to lose the race but it is
obviously quite possible.
I don't think there is anything I can do on the md side to avoid the
bug.
NeilBrown
next prev parent reply other threads:[~2007-12-22 11:58 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-12-18 21:11 mdadm --stop goes off and never comes back? Jon Nelson
2007-12-20 1:45 ` Neil Brown
2007-12-20 2:05 ` Jon Nelson
2007-12-20 2:07 ` Jon Nelson
2007-12-22 11:58 ` Neil Brown [this message]
2007-12-22 13:01 ` Jon Nelson
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