We've contacted Samsung about the problem where performing a mmc erase could hardbrick your phone (i9100, i9100g, n7000, m250 - MAG4FA, VYL00M, and KYL00M with firmware revision 0x19 // T989 and I727 with fw rev 0x12) if it's having a faulty emmc chip.
Read this thread for more informations about it: http://forum.xda-developers.com/show....php?t=1644364
They're working as hard as possible on a clean solution which will be ready soon.
Please be patient and try to not flash any leaked kernels or kernels based on sources where MMC_CAP_ERASE is present.
This app http://forum.xda-developers.com/show...74&postcount=1 can be used to identify if your phone is affected or not.
CM9 kernels are safe to flash.
Update 14:56 CEST:
Patches will be out in form of new official ROMs and also sourcecode releases after testing, which might take some time.
To check whether your phone has the brick bug, download the Got Brickbug app from Chainfire: http://forum.xda-developers.com/show....php?t=1693704
Also do read the article on xda for more info.: http://www.xda-developers.com/androi...hardbrick-fix/