munlock - reenable paging for some parts of memory
int munlock(const void *addr, size_t len));
munlock reenables paging for the memory in the range start-
ing 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 process.
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
On success, munlock returns zero. On error, -1 is returned,
errno is set appropriately, and no changes are made to any
locks in the address space of the process.
ENOMEM Some of the specified address range does not
correspond to mapped pages in the address space of
EINVAL len was not a positive number.
mlock(2), mlockall(2), and munlockall(2).