Explanation of Azul's “pauseless” garbage collector

Question

I\'ve just read this:

http://www.artima.com/lejava/articles/azul_pauseless_gc.html

Although I\'ve some experience with compilers, I\'ve done nothing related

Answer 1

Why would a garbage collector not simply mprotect(region_it's_working_on, PROT_READ) and implement a SIGSEGV handler that updates all pointers to the accessed object? Yes, you'd have to track all pointers to an object of course.