MUNMAP(3P)						     POSIX Programmer's Manual							MUNMAP(3P)

PROLOG

       This  manual page is part of the POSIX Programmer's Manual.  The Linux implementation of this interface may differ (consult the correspond-
       ing Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.

NAME

       munmap - unmap pages of memory

SYNOPSIS

       #include <sys/mman.h>

       int munmap(void *addr, size_t len);

DESCRIPTION

       The munmap() function shall remove any mappings for those entire pages containing any part of the address space of the process starting	at
       addr and continuing for len bytes.  Further references to these pages shall result in the generation of a SIGSEGV signal to the process. If
       there are no mappings in the specified address range, then munmap() has no effect.

       The implementation shall require that addr be a multiple of the page size {PAGESIZE}.

       If a mapping to be removed was private, any modifications made in this address range shall be discarded.

       Any memory locks (see mlock() and mlockall()) associated with this address range shall  be  removed,  as  if  by  an  appropriate  call	to
       munlock().

       If a mapping removed from a typed memory object causes the corresponding address range of the memory pool to be inaccessible by any process
       in the system except through allocatable mappings (that is, mappings of typed memory objects opened with  the  POSIX_TYPED_MEM_MAP_ALLOCAT-
       ABLE  flag), then that range of the memory pool shall become deallocated and may become available to satisfy future typed memory allocation
       requests.

       A mapping removed from a typed memory object opened with the POSIX_TYPED_MEM_MAP_ALLOCATABLE flag shall not affect in any  way  the  avail-
       ability of that typed memory for allocation.

       The behavior of this function is unspecified if the mapping was not established by a call to mmap().

RETURN VALUE

       Upon successful completion, munmap() shall return 0; otherwise, it shall return -1 and set errno to indicate the error.

ERRORS

       The munmap() function shall fail if:

       EINVAL Addresses in the range [addr,addr+len) are outside the valid range for the address space of a process.

       EINVAL The len argument is 0.

       EINVAL The addr argument is not a multiple of the page size as returned by sysconf().

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       The munmap() function is only supported if the Memory Mapped Files option or the Shared Memory Objects option is supported.

RATIONALE

       The munmap() function corresponds to SVR4, just as the mmap() function does.

       It  is  possible  that an application has applied process memory locking to a region that contains shared memory. If this has occurred, the
       munmap() call ignores those locks and, if necessary, causes those locks to be removed.

FUTURE DIRECTIONS

       None.

SEE ALSO

       mlock(),  mlockall(),  mmap(),  posix_typed_mem_open(),	sysconf(),  the  Base  Definitions  volume  of	IEEE Std 1003.1-2001,  <signal.h>,
       <sys/mman.h>

COPYRIGHT

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technol-
       ogy -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
       Electrical  and	Electronics  Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE
       and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can  be  obtained
       online at http://www.opengroup.org/unix/online.html .

IEEE
/The Open Group						       2003								MUNMAP(3P)