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 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_MEM-
       LOCK_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 (Not on Linux) addr was not a multiple of the page size.

       Linux adds

       EINVAL len was negative.

CONFORMING TO
       POSIX.1b, SVr4

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



Linux 2.4			  2003-08-21			   MUNLOCK(2)