munmap(3p) — Linux manual page


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

PROLOG         top

       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         top

       munmap — unmap pages of memory

SYNOPSIS         top

       #include <sys/mman.h>

       int munmap(void *addr, size_t len);

DESCRIPTION         top

       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

       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         top

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

ERRORS         top

       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.

EXAMPLES         top




RATIONALE         top

       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().



SEE ALSO         top

       mlock(3p), mlockall(3p), mmap(3p), posix_typed_mem_open(3p),

       The Base Definitions volume of POSIX.1‐2008, sys_mman.h(0p)

COPYRIGHT         top

       Portions of this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1, 2013 Edition, Standard for Information
       Technology -- Portable Operating System Interface (POSIX), The Open
       Group Base Specifications Issue 7, Copyright (C) 2013 by the
       Institute of Electrical and Electronics Engineers, Inc and The Open
       Group.  (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1
       applied.) 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 .

       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 .

IEEE/The Open Group                 2013                          MUNMAP(3P)

Pages that refer to this page: sys_mman.h(0p)_exit(3p)_Exit(3p)mlock(3p)mlockall(3p)mmap(3p)shm_unlink(3p)