Why does this piece of code in the linux kernel NOT cause a dead loop?

Question

I am reading the linux source code (4.4.45, but should be the same in another version) about initializing the page table at startup, and the code below confused me.

In particular, I read about how to initialize early_level4_pgt. Here is the piece of code in x86_64 , link

Answer 1

fooobar.com/questions/1670159 / ...

jmp 1fmeans go to the mark 1forward (after this instruction).

jmp 1bmeans go 1back one mark (before this instruction).

, jmp 1f 1 , .