XFS, preemption and lock break freezes the box

[GCS <gcs@xxxxxxxxxx>]

Hi!

 Anyone using the combo in subject? It locks the box if I would like to write
on loop mounted filesystems, regardless of it's type. It happens with ext2
as well as XFS, but not if I do not include XFS in the kernel or I disable
the lock break patch. The call trace is __wait_on_buffer, fsync_dev and
sync_dev. I also know that with a vanilla kernel I get a lot of
lock_break: buffer.c:938: count was 0 not 1
messages. If I include XFS, then it changes to
lock_break: buffer.c:919: count was 2 not 551
lock_break: exit.c:252: count was 2 not 1

 A big patch for testing is available at
http://prdownloads.sourceforge.net/lkpc/lkpc-2.4.18-5beta7.patch.bz2

Thanks for any spot,
GCS
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