It just means that the permissions changed on a particularly large block of memory.
That can happen because of something like a call to mprotect or when a very large memory allocation or deallocation occurs – an mmap or munmap call for example.
The first one you list is setting about 320Mb of memory to undefined which is most likely a new allocation, which will be marked as undefined initially. The others are both setting similar sized blocks to noaccess which probably relates to a deallocation of memory.