[dm-crypt] writing greater than 1GB of data through the mapper to a file hangs kernel 3.2.x

Arno Wagner arno at wagner.name
Fri Jul 6 09:34:46 CEST 2012

On Fri, Jul 06, 2012 at 01:22:48AM -0400, .. ink .. wrote:
> > I suspect this is a different problem, e.g. a dying and/or overheating
> > controller. It may also be a RAM problem that only hits on large
> > enough transfers. See cryptsetup FAQ on how to test RAM.
> >
> [....]
> >> first time experience like the one reported here in the second
> >> paragraph: http://www.pclinuxos.com/forum/index.php/topic,106847.msg912803.html#msg912803
> >
> > That looks like a ZuluCrypt artefact to me, not something you would
> > see with cryptsetup.
> >
> The lock up happen when zuluCrypt does the above,write to a file
> through a plain mapper and it happens consistently on my system and on
> the person who first reported it.

Ah. Must have overlooked that part. Sorry.
> I will ask him and others in the forum for their computer specs and to
> use cryptsetup directly to create 3GB of random data to a 4 GB file
> through the mapper and see what happens.

Yes, good idea. Ask the people experencing this for their kernel
versions as well, what filesystem they have the loop-file on
(ext3 in my case), and some speed numbers (the ones from dd are 

If several people have this issue, hardware is very likely not to 
blame. And I have to say that with the recent RAID corruption issue, 
my trust in the 3.x kernels has suffered a bit lately. 

Arno Wagner,    Dr. sc. techn., Dipl. Inform.,   Email: arno at wagner.name 
GnuPG:  ID: 1E25338F  FP: 0C30 5782 9D93 F785 E79C  0296 797F 6B50 1E25 338F
One of the painful things about our time is that those who feel certainty 
are stupid, and those with any imagination and understanding are filled 
with doubt and indecision. -- Bertrand Russell 

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