A detailed explanation of the issue is present in this LKML mail. It says that the trouble started with an EXT4 patch made in Kernel 3.6.2, which was later backported to Kernel 3.5 and 3.4 as well, spreading the problem further and further behind.

Sprint has started rolling out a new software update to fix the mobile data issues plaguing the early adopters of the Sprint’s Galaxy Nexus.