munmap - unmap memory pages

Syntax	#include <sys/mman.h> int munmap(void *addr, size_t len);
Description	The munmap() function removes mappings from pages in the area [addr, addr + len). The value specified in len is rounded to a multiple of the page size defined by sysconf(). Further references to these pages result in a SIGSEGV signal to the process, provided that a new mapping of these pages was not established in the meantime. Areas within the specified interval which are not mmap mappings are ignored.
Return val.	0	if successful.
	-1	if an error occurs. errno is set to indicate the error.
Errors	munmap() will fail if:
	EINVAL	addr is not a multiple of the page size defined by sysconf(), or addresses in the area [addr, addr + len) are not valid for the address area of the process, or the len argument contains a value less than or equal to 0.
See also	mmap(), sysconf(), signal.h, sys/mman.h.