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PROLOG | NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | EXAMPLES | APPLICATION USAGE | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT |
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MUNMAP(3P) POSIX Programmer's Manual MUNMAP(3P)
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.
munmap — unmap pages of memory
#include <sys/mman.h>
int munmap(void *addr, size_t len);
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 may require that addr be a multiple of the
page size as returned by sysconf().
If a mapping to be removed was private, any modifications made in
this address range shall be discarded.
Any memory locks (see mlock(3p) and mlockall(3p)) 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().
Upon successful completion, munmap() shall return 0; otherwise,
it shall return -1 and set errno to indicate the error.
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.
The munmap() function may fail if:
EINVAL The addr argument is not a multiple of the page size as
returned by sysconf().
The following sections are informative.
None.
None.
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.
Most implementations require that addr is a multiple of the page
size as returned by sysconf().
None.
mlock(3p), mlockall(3p), mmap(3p), posix_typed_mem_open(3p),
sysconf(3p)
The Base Definitions volume of POSIX.1‐2017, sys_mman.h(0p)
Portions of this text are reprinted and reproduced in electronic
form from IEEE Std 1003.1-2017, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The
Open Group Base Specifications Issue 7, 2018 Edition, Copyright
(C) 2018 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 .
Any typographical or formatting errors that appear in this page
are most likely to have been introduced during the conversion of
the source files to man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2017 MUNMAP(3P)
Pages that refer to this page: sys_mman.h(0p), _Exit(3p), mlock(3p), mlockall(3p), mmap(3p), shm_unlink(3p)
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HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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