[dm-crypt] System hang during mkfs

Milan Broz gmazyland at gmail.com
Thu Nov 14 22:56:45 CET 2013

On 11/14/2013 10:29 PM, Tim wrote:
> Hello,
> I have run into a serious issue (system hang) while trying to create a
> luks-based loopback disk.  I have reported this issue to Debian here:
>   http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=729600
> That should have most of the technical details you need to start.  I
> suspect the behavior I'm seeing is very similar to this:
>   http://www.saout.de/pipermail/dm-crypt/2012-July/002544.html
> I am now running memtester on most of my VM's available memory and it
> is now on loop #3 with no issues identified.
> I'm really surprised to run across an issue like this under a stable
> kernel, so any advice you could give on how to further debug this
> would be greatly appreciated.

Well, the kernel Debian stable kernel, so it should be handled
really handled by the Debian distro bugzilla.
(Otherwise, please try more recent, ideally 3.12 stable kernel.
Using loop devices is quite common and I do not think there are recent
problems here.)

Also try use loop directly. Does mkfs works ok? What is the underlying
filesystem and mount parameters (on which image resides)?

If it "locks" paste kernel trace to bugzilla (through sysrq,
"echo t > /proc/sysrq-trigger" and see syslog.)

(It seems to me more like problem with loop device or combination
than with dmcrypt. Anyway, if you are able to reproduce it on upstream
kernel, add device mapper devel list to cc  - dm-devel at redhat.com)


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