Bug#351393: [Pkg-cryptsetup-devel] Bug#351393: Might as well close this

[Jonas Meurer]

On 06/03/2006 Jonas Meurer wrote:
> > As far as I remember, the system literally froze. I was running Xorg
> > (6.9 with the nvidia driver) at the time and I think even the mouse
> > cursor wouldn't move.
> 
> i just tested this now, as i was on the console last time. i can verify
> that X freezes completely. and i tested the same command with 1GB
> swapfile and without any active swap in X too. no freeze, mouse still
> moves, ctrl+c stops the command after some seconds.

i've reconsidered the whole issue, and came to the conclusion, that
the bug must be either in kernel loopback support, device-mapper support
or dm-crypt support. it may be even in cryptsetup(-luks), but i don't
believe that.

i've tested now with an unencrypted loopback device pointing to a 1GB
/swap file, and after some (more) time the system crashed in the same
way as with an encrypted swapfile.
this might indicate that the bug is in loopback device support, but i'dd
like you to verify this.

could you try to reproduce the crash with the encrypted 1GB swapfile,
and then do the same with an uncrypted 1GB swapfile over a loopback
device?

this is what i did:

[ create 1GB file at /swap ]
# dd if=/dev/urandom of=/swap bs=1024 count=1048576

[ setup encrypted swap ]
# losetup /dev/loop0 /swap
# cryptsetup -d /dev/random create cswap /dev/loop0
# mkswap /dev/mapper/cswap
# swapoff -a
# swapon /dev/mapper/cswap

[ run the test ]
# perl -e '@foo = (); push(@foo, "x"x1000) for (1..10**5); fork for (1..10**5); sleep 60'
[ system crash; reset ]

[ setup uncrypted swap ]
# losetup /dev/loop0 /swap
# mkswap /dev/loop0
# swapoff -a
# swapon /dev/loop0

[ run the test ]
# perl -e '@foo = (); push(@foo, "x"x1000) for (1..10**5); fork for (1..10**5); sleep 60'
[ system crash; reset ]

i'dd also like to test whether uncrypted device-mapper devices suffer
from this bug, but i don't know how to setup a device-mapper target that
does nothing than linking to the original file at /swap.

please try the above, and report what you discovered. i'dd like to
inform (whatever) upstream as soon as possible, but i'dd also like to
have a verification from you before.

...
 jonas