Oh, another change in segfault-3.patch:
 - disable signal handler before the first call to segfault_enter() 
and the last call to segfault_exit()

About the memory footprint: it would be possible to use variable size 
buffer using malloc() and then realloc(). But static buffers are 
easier to use, and I don't want to play with malloc() while I'm 
handling a segmentation fault or stack overflow :-)