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munmap(3p) — Linux manual page

MUNMAP(3P)              POSIX Programmer's ManualMUNMAP(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_tlen);

DESCRIPTION        top

       Themunmap() function shall remove any mappings for those entire       pages containing any part of the address space of the process       starting ataddr and continuing forlen 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, thenmunmap() has no effect.       The implementation may require thataddr be a multiple of the page       size as returned bysysconf().       If a mapping to be removed was private, any modifications made in       this address range shall be discarded.       Any memory locks (seemlock(3p) andmlockall(3p)) associated with       this address range shall be removed, as if by an appropriate call       tomunlock().       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 tommap().

RETURN VALUE        top

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

ERRORS        top

       Themunmap() function shall fail if:EINVALAddresses in the range [addr,addr+len) are outside the              valid range for the address space of a process.EINVALThelen argument is 0.       Themunmap() function may fail if:EINVALTheaddr argument is not a multiple of the page size as              returned bysysconf().The following sections are informative.

EXAMPLES        top

       None.

APPLICATION USAGE        top

       None.

RATIONALE        top

       Themunmap() function corresponds to SVR4, just as themmap()       function does.       It is possible that an application has applied process memory       locking to a region that contains shared memory. If this has       occurred, themunmap() call ignores those locks and, if necessary,       causes those locks to be removed.       Most implementations require thataddr is a multiple of the page       size as returned bysysconf().

FUTURE DIRECTIONS        top

       None.

SEE ALSO        top

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)

COPYRIGHT        top

       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 athttp://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, seehttps://www.kernel.org/doc/man-pages/reporting_bugs.html .IEEE/The Open Group                2017MUNMAP(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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