.\"	$OpenBSD: munmap.2,v 1.21 2024/01/21 17:00:42 deraadt Exp $
.\"	$NetBSD: munmap.2,v 1.5 1995/02/27 12:35:03 cgd Exp $
.\"
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.\"	@(#)munmap.2	8.2 (Berkeley) 4/15/94
.\"
.Dd $Mdocdate: January 21 2024 $
.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 mimmutable 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.