redhat man page for munlock

MUNLOCK(2)						     Linux Programmer's Manual							MUNLOCK(2)

NAME
       munlock - reenable paging for some parts of memory

SYNOPSIS
       #include <sys/mman.h>

       int munlock(const void *addr, size_t len);

DESCRIPTION
       munlock	reenables  paging for the memory in the range starting at addr with length len bytes. All pages which contain a part of the speci-
       fied 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  <lim-
       its.h> indicates the number of bytes per page.

RETURN VALUE
       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.

ERRORS
       ENOMEM Some of the specified address range does not correspond to mapped pages in the address space of the process.

       EINVAL len was not a positive number.

CONFORMING TO
       POSIX.1b, SVr4

SEE ALSO
       mlock(2), mlockall(2), munlockall(2)

Linux 1.3.43							    1995-11-26								MUNLOCK(2)