.\"	$OpenBSD: munmap.2,v 1.20 2022/10/07 15:21:04 deraadt Exp $
.\"	$NetBSD: munmap.2,v 1.5 1995/02/27 12:35:03 cgd Exp $
.\"
.\" Copyright (c) 1991, 1993
.\"	The Regents of the University of California.  All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 3. Neither the name of the University nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\"	@(#)munmap.2	8.2 (Berkeley) 4/15/94
.\"
.Dd $Mdocdate: October 7 2022 $
.Dt MUNMAP 2
.Os
.Sh NAME
.Nm munmap
.Nd remove a mapping
.Sh SYNOPSIS
.In sys/mman.h
.Ft int
.Fn munmap "void *addr" "size_t len"
.Sh DESCRIPTION
The
.Fn munmap
system call
deletes the mappings for the specified address range,
and causes further references to addresses within the range
to generate invalid memory references.
.Sh RETURN VALUES
.Rv -std
.Sh ERRORS
.Fn munmap
will fail if:
.Bl -tag -width Er
.It Bq Er EINVAL
The
.Fa addr
and
.Fa len
parameters
specify a region that would extend beyond the end of the address space,
or some part of the region being unmapped is not part of the currently
valid address space.
.It Bq Er EPERM
The
.Fa addr
and
.Fa len
parameters
specify a region which contains at least one page marked immutable.
.El
.Sh SEE ALSO
.Xr madvise 2 ,
.Xr mlock 2 ,
.Xr mlockall 2 ,
.Xr mmap 2 ,
.Xr mprotect 2 ,
.Xr msync 2 ,
.Xr getpagesize 3
.Sh STANDARDS
When
.Fa len
is non-zero, the
.Fn munmap
function conforms to
.St -p1003.1-2008 .
.Sh HISTORY
The
.Fn munmap
system call has been available since
.Bx 4.3 Net/2 .
.Sh CAVEATS
.St -p1003.1-2008
specifies that
.Fn munmap
shall fail with
.Er EINVAL
if
.Fa len
is 0.
.Ox
performs no action in this case.