munlock reenables paging for the memory in the range starting at
addr with length len bytes. All pages which contain a part of
the specified memory range can after calling munlock be moved to
external swap space again by the kernel.
Memory locks do not stack, i.e., pages which have been locked several times by
calls to mlock or mlockall will be unlocked by a single call to
munlock for the corresponding range or by munlockall. Pages
which are mapped to several locations or by several processes stay locked into
RAM as long as they are locked at least at one location or by at least one
On POSIX systems on which mlock and munlock are available,
_POSIX_MEMLOCK_RANGE is defined in <unistd.h> and the value
PAGESIZE from <limits.h> indicates the number of bytes per page.