I have SiI 3112 RAID card in one machive. At some point (half a year ago or so) I was unable to mount my LVM1 device (the LVM has been builded but data has been messed up so mounting was not possible). Now, few weeks ago after reboot, the second LVM2 device has not been mounted and I saw SIGSEGV from LVM2 utils when machine start (rc.sysinit). The array has been mounted by hand by issuing "vgchange -a y" by hand (stil SIGSEGV, but device was then up). After removin dmraid package, all is like before. I'm able to mount LVM array and LVM2 comes up after the reboot too, no SIGSEGV. This is probably because I have SW RAID configured on the card (in SiI card's BIOS) even I do not use it. But lvm2 utils shoud not SIGSEGV. I'll post core soon (when I'll have console access again).
There were many fixes in lvm2 package since this time. If you see this problem again, please reopen this bug, run vgchange command with debugging enabled (add -vvvv) and attach log file to this bugzilla. Also please attach file created by lvmdump diagnostic utility, thanks. (And this can be problem with empty mapping table too - recently fixed upstream.)