Re: Major XFS problems...

[Eric Sandeen <sandeen@xxxxxxx>]

Jakob Oestergaard wrote:

> Second XFS bug:
> ---------------
> Also causes the 'kernel BUG at fs/xfs/support/debug.c:106' message to be
> printed. This bug is not solved by applying the simple patch to the
> first problem.
>
> How well known this problem is, I don't know - I can get more details on
> this if anyone is actually interested in working on fixing XFS.

Do you have -any- details on this problem... pretty much nothing to go 
on here.

> Third XFS bug:
> --------------
> XFS causes lowmem oom, triggering the OOM killer. Reported by
> as@xxxxxxxxxxxx on the 18th of august.
>
> On the 24th of august, William Lee Irwin gives some suggestions and
> mentions  "xfs has some known bad slab behavior."

I'm curious to know what that means... :)

> So, it's normal to OOM the lowmem with XFS? Again, more info can be
> presented if anyone cares about fixing this.

of course, please file a bug with all info you have.  How do you know 
it's xfs causing the oom killer to kick in?  Surely there are other 
memory consumers on the box; also how much memory is in the box to start 
with?

This may have as much to do with the way linux (2.4, anyway) caches 
dentries; xfs has structures that can't be freed as long as the dentry 
still has a reference.

> Stability on large filesystems:
> -------------------------------
> On a 600+G filesystem with some 17M files, we are currently unable to
> run a backup of the filesystem.
>
> Some 4-8 hours after the backup has started, the dreaded 'debug.c:106'
> message will appear (at some random place thru the filesystem - it is
> not a consistent error in one specific location in the filesystem), and
> the server will need a reboot.

a report of "debug.c:106 message" is not helpful; this is a generic 
error printing routine which will BUG() the box if CE_PANIC was 
specified in the error.  We need all error messages leading up to this 
to know how you got here.

 > Does anyone actually use XFS for serious file-serving?  (yes, I run it
> on my desktop at home and I don't have problems there - such reports are
> not really relevant).

yes.  http://oss.sgi.com/projects/xfs/xfs_users.html

> Is anyone actually maintaining/bugfixing XFS?  Yes, I know the
> MAINTAINERS file, but I am a little bit confused here - seeing that
> trivial-to-trigger bugs that crash the system and have simple fixes,
> have not been fixed in current mainline kernels.

Yes, sgi is maintaining it.  Perhaps you've missed the large volume of 
commits on the linux-xfs list and on lkml.  :)

-Eric