registers, stack, call trace are all the information you get about what happened, this is the most important part of an oops report.

did you really recompile all sources that refer fs.h? you have to make sure every place where the modified structure is allocated or used is recompiled with the new structure layout, or else different parts of the kernel talk about different memory locations for variables.

you cannot use floating point in the kernel, this includes the type 'double'.