The mmap()
system call creates a mapping for a range of virtual addresses; it
has a long list of options controlling just how that mapping should work.
Ming Lin is proposing
the addition of yet another option, called MAP_NOSIGBUS, which
changes the kernel’s response when a process accesses an unmapped address.
What this option does is relatively easy to understand; why it is
useful takes a bit more explanation.

Source: LWN.net – [$] Suppressing SIGBUS signals