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munmap(3) [linux man page]

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

NAME
munmap - unmap pages of memory SYNOPSIS
#include <sys/mman.h> int munmap(void *addr, size_t len); DESCRIPTION
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 shall require that addr be a multiple of the page size {PAGESIZE}. 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_ALLOCAT- ABLE 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 avail- ability 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
Upon successful completion, munmap() shall return 0; otherwise, it shall return -1 and set errno to indicate the error. ERRORS
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. EINVAL The addr argument is not a multiple of the page size as returned by sysconf(). The following sections are informative. EXAMPLES
None. APPLICATION USAGE
The munmap() function is only supported if the Memory Mapped Files option or the Shared Memory Objects option is supported. RATIONALE
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. FUTURE DIRECTIONS
None. SEE ALSO
mlock() , mlockall() , mmap() , posix_typed_mem_open() , sysconf() , the Base Definitions volume of IEEE Std 1003.1-2001, <signal.h>, <sys/mman.h> COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technol- ogy -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 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 . IEEE
/The Open Group 2003 MUNMAP(P)

Check Out this Related Man Page

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

PROLOG
This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (consult the correspond- ing Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux. NAME
mlock, munlock - lock or unlock a range of process address space (REALTIME) SYNOPSIS
#include <sys/mman.h> int mlock(const void *addr, size_t len); int munlock(const void *addr, size_t len); DESCRIPTION
The mlock() function shall cause those whole pages containing any part of the address space of the process starting at address addr and continuing for len bytes to be memory-resident until unlocked or until the process exits or execs another process image. The implementation may require that addr be a multiple of {PAGESIZE}. The munlock() function shall unlock those whole pages containing any part of the address space of the process starting at address addr and continuing for len bytes, regardless of how many times mlock() has been called by the process for any of the pages in the specified range. The implementation may require that addr be a multiple of {PAGESIZE}. If any of the pages in the range specified to a call to munlock() are also mapped into the address spaces of other processes, any locks established on those pages by another process are unaffected by the call of this process to munlock(). If any of the pages in the range specified by a call to munlock() are also mapped into other portions of the address space of the calling process outside the range speci- fied, any locks established on those pages via the other mappings are also unaffected by this call. Upon successful return from mlock(), pages in the specified range shall be locked and memory-resident. Upon successful return from munlock(), pages in the specified range shall be unlocked with respect to the address space of the process. Memory residency of unlocked pages is unspecified. The appropriate privilege is required to lock process memory with mlock(). RETURN VALUE
Upon successful completion, the mlock() and munlock() functions shall return a value of zero. Otherwise, no change is made to any locks in the address space of the process, and the function shall return a value of -1 and set errno to indicate the error. ERRORS
The mlock() and munlock() functions shall fail if: ENOMEM Some or all of the address range specified by the addr and len arguments does not correspond to valid mapped pages in the address space of the process. The mlock() function shall fail if: EAGAIN Some or all of the memory identified by the operation could not be locked when the call was made. The mlock() and munlock() functions may fail if: EINVAL The addr argument is not a multiple of {PAGESIZE}. The mlock() function may fail if: ENOMEM Locking the pages mapped by the specified range would exceed an implementation-defined limit on the amount of memory that the process may lock. EPERM The calling process does not have the appropriate privilege to perform the requested operation. The following sections are informative. EXAMPLES
None. APPLICATION USAGE
None. RATIONALE
None. FUTURE DIRECTIONS
None. SEE ALSO
exec(), exit(), fork(), mlockall(), munmap(), the Base Definitions volume of IEEE Std 1003.1-2001, <sys/mman.h> COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technol- ogy -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 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 . IEEE
/The Open Group 2003 MLOCK(3P)
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