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



PPRROOLLOOGG
       This manual page is part of the POSIX Programmer's Manual.  The OS
       implementation of this interface may differ (consult the corresponding
       OS manual page for details of OS behavior), or the interface may not be
       implemented on OS.


NNAAMMEE
       munmap -- unmap pages of memory

SSYYNNOOPPSSIISS
       #include <sys/mman.h>

       int munmap(void *_a_d_d_r, size_t _l_e_n);

DDEESSCCRRIIPPTTIIOONN
       The _m_u_n_m_a_p() function shall remove any mappings for those entire pages
       containing any part of the address space of the process starting at
       _a_d_d_r and continuing for _l_e_n 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 _m_u_n_m_a_p() has
       no effect.

       The implementation may require that _a_d_d_r be a multiple of the page size
       as returned by _s_y_s_c_o_n_f().

       If a mapping to be removed was private, any modifications made in this
       address range shall be discarded.

       Any memory locks (see _m_l_o_c_k() and _m_l_o_c_k_a_l_l()) associated with this
       address range shall be removed, as if by an appropriate call to
       _m_u_n_l_o_c_k().

       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 _m_m_a_p().

RREETTUURRNN VVAALLUUEE
       Upon successful completion, _m_u_n_m_a_p() shall return 0; otherwise, it
       shall return -1 and set _e_r_r_n_o to indicate the error.

EERRRROORRSS
       The _m_u_n_m_a_p() function shall fail if:

       EEIINNVVAALL Addresses in the range [_a_d_d_r,_a_d_d_r+_l_e_n) are outside the valid
              range for the address space of a process.

       EEIINNVVAALL The _l_e_n argument is 0.

       The _m_u_n_m_a_p() function may fail if:

       EEIINNVVAALL The _a_d_d_r argument is not a multiple of the page size as returned
              by _s_y_s_c_o_n_f().

       _T_h_e _f_o_l_l_o_w_i_n_g _s_e_c_t_i_o_n_s _a_r_e _i_n_f_o_r_m_a_t_i_v_e_.

EEXXAAMMPPLLEESS
       None.

AAPPPPLLIICCAATTIIOONN UUSSAAGGEE
       None.

RRAATTIIOONNAALLEE
       The _m_u_n_m_a_p() function corresponds to SVR4, just as the _m_m_a_p() 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
       _m_u_n_m_a_p() call ignores those locks and, if necessary, causes those locks
       to be removed.

       Most implementations require that _a_d_d_r is a multiple of the page size
       as returned by _s_y_s_c_o_n_f().

FFUUTTUURREE DDIIRREECCTTIIOONNSS
       None.

SSEEEE AALLSSOO
       _m_l_o_c_k(), _m_l_o_c_k_a_l_l(), _m_m_a_p(), _p_o_s_i_x___t_y_p_e_d___m_e_m___o_p_e_n(), _s_y_s_c_o_n_f()

       The Base Definitions volume of POSIX.1-2008, <<ssyyss__mmmmaann..hh>>

CCOOPPYYRRIIGGHHTT
       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 http://www.unix.org/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                  2013                            MUNMAP(3)
