2.6.39-rc3, 2.6.39-rc4: XFS lockup - regression since 2.6.38

[Dave Chinner]

On Wed, May 04, 2011 at 12:57:36AM +0000, Jamie Heilman wrote:
> Dave Chinner wrote:
> > OK, so the common elements here appears to be root filesystems
> > with small log sizes, which means they are tail pushing all the
> > time metadata operations are in progress. Definitely seems like a
> > race in the AIL workqueue trigger mechanism. I'll see if I can
> > reproduce this and cook up a patch to fix it.
> 
> Is there value in continuing to post sysrq-w, sysrq-l, xfs_info, and
> other assorted feedback wrt this issue?  I've had it happen twice now
> myself in the past week or so, though I have no reliable reproduction
> technique.  Just wondering if more data points will help isolate the
> cause, and if so, how to be prepared to get them.

Not really. I think I know where the problem lies, but I currently
lack a reproducer. There's also been another regression I've only
just got to the bottom of, so I haven't really had a chance to focus
properly on this one yet. Log space hangs like this have
historically been difficult to reproduce reliably....

Cheers,

Dave.
-- 
Dave Chinner
david at fromorbit.com