Description of problem:
when I try to snapshot my root lv it hangs here:

==========================================================================
[root@RAWHIDE ~]# lvcreate -v -s -n snaproot -L 100M /dev/mainvg/rootlv
    Setting chunksize to 8 sectors.
    Setting logging type to disk
    Finding volume group "mainvg"
    Archiving volume group "mainvg" metadata (seqno 114).
    Creating logical volume snaproot
    Creating volume group backup "/etc/lvm/backup/mainvg" (seqno 115).
    Found volume group "mainvg"
    Creating mainvg-snaproot
    Loading mainvg-snaproot table (253:2)
    Resuming mainvg-snaproot (253:2)
    Clearing start of logical volume "snaproot"
    Creating logical volume snapshot0
    Found volume group "mainvg"
    Found volume group "mainvg"
    Creating mainvg-rootlv-real
    Loading mainvg-rootlv-real table (253:3)
    Resuming mainvg-rootlv-real (253:3)
    Loading mainvg-rootlv table (253:0)
    Creating mainvg-snaproot-cow
    Loading mainvg-snaproot-cow table (253:4)
    Resuming mainvg-snaproot-cow (253:4)
    Loading mainvg-snaproot table (253:2)
    Suspending mainvg-rootlv (253:0) with filesystem sync with device flush
=========================================================================

I/O on the system is then blocked and reboot needed.

lv's other than the root lv I can successfully snapshot.

Version-Release number of selected component (if applicable):
kernel-2.6.35-0.2.rc3.git0.fc14.x86_64
lvm2-2.02.67-1.fc14.x86_64
device-mapper-1.02.49-1.fc14.x86_64

Additional info:
If I revert back to kernel-2.6.34-20.fc14.x86_64, snapshots of my root lv are successful again.

This install is running in a qemu-kvm if that matters.