Does this mean the memory of my good old trusty N900 is getting faulty? What can I do?
ECC errors is a normal phenomena on OneNAND and they happen quite often. Flash-aware file-systems like JFFS2 or UBIFS are able to handle them gracefully.
since ECC errors are supposed to be handled by upper level SW, we do not really have to print these messages, and we may consider them as debugging prints.