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mlock(3p) — Linux manual page

MLOCK(3P)               POSIX Programmer's ManualMLOCK(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

       mlock, munlock — lock or unlock a range of process address space       (REALTIME)

SYNOPSIS        top

       #include <sys/mman.h>       int mlock(const void *addr, size_tlen);       int munlock(const void *addr, size_tlen);

DESCRIPTION        top

       Themlock() function shall cause those whole pages containing any       part of the address space of the process starting at addressaddr       and continuing forlen bytes to be memory-resident until unlocked       or until the process exits orexecs another process image. The       implementation may require thataddr be a multiple of {PAGESIZE}.       Themunlock() function shall unlock those whole pages containing       any part of the address space of the process starting at addressaddr and continuing forlen bytes, regardless of how many timesmlock() has been called by the process for any of the pages in the       specified range. The implementation may require thataddr be a       multiple of {PAGESIZE}.       If any of the pages in the range specified to a call tomunlock()       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 tomunlock().  If any of the pages in       the range specified by a call tomunlock() are also mapped into       other portions of the address space of the calling process outside       the range specified, any locks established on those pages via the       other mappings are also unaffected by this call.       Upon successful return frommlock(), pages in the specified range       shall be locked and memory-resident. Upon successful return frommunlock(), pages in the specified range shall be unlocked with       respect to the address space of the process. Memory residency of       unlocked pages is unspecified.       Appropriate privileges are required to lock process memory withmlock().

RETURN VALUE        top

       Upon successful completion, themlock() andmunlock() 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 seterrno to indicate the error.

ERRORS        top

       Themlock() andmunlock() functions shall fail if:ENOMEMSome or all of the address range specified by theaddr andlen arguments does not correspond to valid mapped pages in              the address space of the process.       Themlock() function shall fail if:EAGAINSome or all of the memory identified by the operation could              not be locked when the call was made.       Themlock() andmunlock() functions may fail if:EINVALTheaddr argument is not a multiple of {PAGESIZE}.       Themlock() function may fail if:ENOMEMLocking the pages mapped by the specified range would              exceed an implementation-defined limit on the amount of              memory that the process may lock.EPERMThe calling process does not have appropriate privileges to              perform the requested operation.The following sections are informative.

EXAMPLES        top

       None.

APPLICATION USAGE        top

       None.

RATIONALE        top

       None.

FUTURE DIRECTIONS        top

       None.

SEE ALSO        top

exec(1p),exit(3p),fork(3p),mlockall(3p),munmap(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                2017MLOCK(3P)

Pages that refer to this page:sys_mman.h(0p), _Exit(3p), mlockall(3p), munlock(3p), munmap(3p)

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