Re: [BUG] domU hangs when mkfs over a cryptsetup mapped from a file lying on rootfs

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Wed, Aug 14, 2013 at 06:57:31PM +0200, tVos wrote:
> Hello xen-developers,
> 
> i think i found a bug, so i report now everything i did and what happened
> and what i expected below, and let you tell me if this bug is confirmed.
> 
> -----BEGIN BUG REPORT-----
> Distro: Debian 7.1 Wheezy
> XEN: xen-hypervisor-4.1-amd64          4.1.4-3+deb7u1
> Kernel: 3.2.0-4-amd64 #1 SMP Debian 3.2.46-1 x86_64 GNU/Linux
> 
> 
> First i created a new domU:
> xen-create-image --hostname=testtest --ip=10.3.4.1 --arch=amd64
> --dist=wheezy --size=30Gb --memory=256Mb --vcpus=1 --verbose --noswap
> --dir=/media/xen
> 
> I startet it and got into console with:
> xm create testtest.cfg && xm console testtest
> 
> I logged in and installed cryptsetup and gddrescue:
> apt-get update && apt-get install cryptsetup gddrescue
> 
> I created a 10GB file from /dev/zero:
> ddrescue -b 4096 -s 10G /dev/zero ./testvolume
> 
> Then I luksFormatet and mapped it:
> cryptsetup luksFormat ./testvolume
> cryptsetup luksOpen ./testvolume testvolume
> 
> *** Until here everything was normal and as expected. ***
> 
> Now i tried to mkfs the mapped crypted file:
> mkfs -t ext3 /dev/mapper/testvolume
> 
> the mkfs.ext3 got until "Writing inode tables: 22/75" and got stuck there.
> The domU hangsup in a way that it doesn't ract anymore. No deamon reacts,
> getty don't react anymore, and sometimes the dmesg of the domU says, that
> a process did hang more than 120sec.
> 
> xentop and xm list says the domU are in blocking mode, the other domUs
> continue working normaly and the host also works normaly.
> 
> no messages concerning this in host dmesg nor in xen dmesg. Nothing in the
> logfiles.
> 
> The only way to recover the domU is waiting a _very_ long period of time,
> usually 12-48h then it suddenly continues and finish the mkfs.ext; or to
> xm destroy the domU and create it again.
> 
> I tested this on my Xen setup as well as on other similar XEN setups, and
> diferent parameters such like guestroofs on a file, or als volumegroup,
> more or less RAM, more or less disk, more or less CPUs, with and without
> swap.
> 
> All setups are standart debian setups out of the box.
> -----END BUG REPORT----
> 
> Please tell me what more infos you need, i will try to provide it asap.
> Also please tell me if i should try somthing or reconfigure something and
> try this scenario again.

This looks like another issue that had been reported in the past
where the guest image was created on top of a crypted LVM. And when
they tried to scp a large file to it would hang. They were using 2.6.32
as guest and 3.5 as dom0.

But you are doing it a bit differently (I think). Could you explain to
me what is the underlaying storage for the guest? I see --dir=/media/xen.

Is that over NFS? Or is that a local file?
> 
> Assistance will be apreciated. Many thanks in advance.
> 
> Sincerely,
> tVos
> 
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