This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface

       None.

       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(3POSIX)

       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() 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().

       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().

       Thefollowingsectionsareinformative.

       None.

       None.

       munmap — unmap pages of memory

       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.

       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().

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

mlock(), mlockall(), mmap(), posix_typed_mem_open(), sysconf()

       The Base Definitions volume of POSIX.1‐2017, <sys_mman.h>

       #include <sys/mman.h>

       int munmap(void *addr, size_t len);