Re: Kernel panics with dazukofs

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Re: Kernel panics with dazukofs

jim burns
Ok, here's a summary of my experience with dazukofs on SuSE 10.2, reiserfs.

1) Automatically eliminated as candidates for being overlaid are /dev, /proc,
& /sys. I get major samba problems if I try (100% cpu usage), and my virus
checker (antivir) doesn't even include /sys & /proc in scans, anyway.

2) The most common problem is 'umount' segfault-ing if I try to overlay
certain directories. (This would cause shutdowns to hang
after /etc/init.d/boot.localfs. Directories that segfault umount are also
most likely to be the ones that panic KDE, starting with kswapd0.) The first
problem was with /lib. I then tried to overlay only the subdirectories
of /lib, and ended up with /lib/security as the only one that segfault-ed
(not /lib/modules, as I originally feared). I then tried moving /lib/security
(contains pam libraries that kdm and login leep open) to another directory
that wasn't overlaid, and sym-linking to it, but /lib still segfault-ed
umount. Obviously, this is undesirable to only overlay subdirectories
of /lib, and not the libraries in /lib.

I had similar problems with /usr, and had to check which subdirectories were
segfault-ing umount: /usr/lib & /usr/X11R6 (which really only has fonts, and
my nvidia libraries, since I have Xorg 7).

Not being able to overlay the libraries in both /lib and /usr/lib means 90% of
my program libraries are unprotected.

3) I also couldn't overlay /var, with umount complaining
that /var/lib/nfs/rpc_pipefs was busy. No segfault, no hang in shutdown, but
I just erred on the side of caution, and only overlay-ed the other
directories of /var.

I didn't try seeing which subdirs of /var/lib could be overlay-ed, as I
already have 40 overlays in my fstab, and dazukofs seems to have a hard disk
space overhead - I'm missing around 30Mb. Since there are some 47
subdirectories of /var/lib, I left well enough alone.

4) I couldn't overlay /sbin or /usr/sbin - I get some services reporting
failure on startup, even though the processes themselves are visible in ps.
This causes problems with .pid files not being written, and errors reported
on service stops. Even after eliminating those two dirs, 'dbus' was reporting
failure on startup, and I had to not overlay /usr/bin.

Since antivir doesn't start until after most of these services are started, I
doubt antivir is slowing things down.

At least I can still overlay /bin & /lib/modules.

5) Finally, I don't overlay mount points. I don't mind not overlay-ing remote
mount points - servers should be responsible for their own virus checking.
However, I can't even overlay local mount points - they just disappear. This
includes a win98 vfat mount, and an xp ntfs mount using the fuse based
ntfs-3g r/w driver. I can't even overlay the parent directory of these mount
points - the local mounts just disappear.

Any ideas? Thanx.

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Re: Re: Kernel panics with dazukofs

John Ogness-2
jim burns wrote:
> Ok, here's a summary of my experience with dazukofs on SuSE 10.2, reiserfs.
> <snip>
> Any ideas?

Thank you for this information. We definately have a lot to start with
now. I will get an OpenSUSE 10.2 system up and running to make sure I
can reproduce all these problems. There are several things that I am
interested in testing:

1. Creating a NOOP stackable filesystem with FiST and see if the same
problems occur. I suspect they will, which would isolate the problems to
the FiST project.

2. Trying the same tests using ecryptfs and see if the same problems
occur. ecryptfs is part of the latest mainline kernel and is also based
on the FiST project (with several modifications). If ecryptfs runs with
less problems, it may be easier to track down where the problems are.

John Ogness

Dazuko Maintainer

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