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MUNMAP
Section: POSIX Programmer's Manual (3P)
Updated: 2003
Index
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PROLOG
This manual page is part of the POSIX Programmer's Manual.
The Linux implementation of this interface may differ (consult
the corresponding 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_ALLOCATABLE 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 availability 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 Technology
-- 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 .
Index
- PROLOG
-
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- RETURN VALUE
-
- ERRORS
-
- EXAMPLES
-
- APPLICATION USAGE
-
- RATIONALE
-
- FUTURE DIRECTIONS
-
- SEE ALSO
-
- COPYRIGHT
-
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