From mboxrd@z Thu Jan 1 00:00:00 1970 From: Neil Brown Subject: Re: mdadm --stop goes off and never comes back? Date: Sat, 22 Dec 2007 22:58:57 +1100 Message-ID: <18284.64513.783072.915203@notabene.brown> References: <18281.51489.845404.884191@notabene.brown> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: message from Jon Nelson on Wednesday December 19 Sender: linux-raid-owner@vger.kernel.org To: Jon Nelson Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids On Wednesday December 19, jnelson-linux-raid@jamponi.net wrote: > On 12/19/07, Jon Nelson wrote: > > On 12/19/07, Neil Brown 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