[dm-crypt] Can't mount my LUKS crypted disk after kernel update / reboot

Milan Broz gmazyland at gmail.com
Sun Dec 16 11:49:55 CET 2012

On 12/16/2012 10:24 AM, Javier Juan Martínez Cabezón wrote:
> I think I answer too fast before, sorry.
> Did strings answer something known in the device?
> Are you sure that this is true?   aes-xts-essiv:sha256
> Which cipher did you use with cryptsetup 1.1?

Please do not confuse it even more, this is LUKS, not plain device
where default cipher changed.

So it is LUKS and if there was no header rewrite, parameters are correct,
(there was no reformat and cipher parameter is in LUKS header).

If it is properly unlocked, master key is correct as well.

So I guess there were no LUKS format and dmcrypt had no obvious problems
in this kernel, I would say, the problem is not in this layer.

cryptsetup userspace should not be problem, to verify it
run dmsetup table --showkeys and compare output with old/new version
- if it is same there is definitely no problem in
userspace / LUKS

So IMHO the problem is in MD layer, ext4, or in some unexpected device
rewrite during update or so.

- check syslog, mainly time before/after upgrade.
Maybe it was broken already there. 

- check blkid -p on the device - does it detect some known signature?

- boot to old kernel, does it work? Or it is broken?

(And read the FAQ, there is a lot of other hints.)

>>> md126 : active raid0 sda5[0] sdb5[1]
>>> 5832190976 blocks super 1.2 512k chunks

>>> cryptsetup luksDump /dev/md126

So this is your device, RAID0. Read first kb and
check what's there now with blkid etc.


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