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

PROLOG
       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
       mlockall, munlockall - lock/unlock  the  address  space  of  a  process
       (REALTIME)
SYNOPSIS
       #include <sys/mman.h>
       int mlockall(int flags);
       int munlockall(void);

DESCRIPTION
       The  mlockall()  function  shall  cause  all of the pages mapped by the
       address space of a process to  be  memory-resident  until  unlocked  or
       until the process exits or execs another process image. The flags argu-
       ment determines whether the pages to  be  locked  are  those  currently
       mapped  by  the  address space of the process, those that are mapped in
       the future, or both. The flags argument is constructed  from  the  bit-
       wise-inclusive  OR  of one or more of the following symbolic constants,
       defined in <sys/mman.h>:
       MCL_CURRENT
              Lock all of the pages currently mapped into the address space of
              the process.
       MCL_FUTURE
              Lock  all of the pages that become mapped into the address space
              of the process in the future, when  those  mappings  are  estab-
              lished.

       If  MCL_FUTURE  is  specified, and the automatic locking of future map-
       pings eventually causes the amount  of  locked  memory  to  exceed  the
       amount of available physical memory or any other implementation-defined
       limit, the behavior is implementation-defined. The manner in which  the
       implementation  informs  the  application  of  these situations is also
       implementation-defined.
       The munlockall() function shall unlock all currently  mapped  pages  of
       the address space of the process. Any pages that become mapped into the
       address space of the process after a call to munlockall() shall not  be
       locked,  unless  there  is an intervening call to mlockall() specifying
       MCL_FUTURE or a subsequent call to mlockall()  specifying  MCL_CURRENT.
       If  pages  mapped into the address space of the process are also mapped
       into the address spaces of other processes and are locked by those pro-
       cesses,  the  locks  established  by the other processes shall be unaf-
       fected by a call by this process to munlockall().
       Upon successful return from  the  mlockall()  function  that  specifies
       MCL_CURRENT,  all  currently mapped pages of the process' address space
       shall be memory-resident and locked. Upon return from the  munlockall()
       function,  all  currently  mapped  pages  of the process' address space
       shall be unlocked with respect to the process' address space. The  mem-
       ory residency of unlocked pages is unspecified.
       The  appropriate  privilege  is  required  to  lock process memory with
       mlockall().
RETURN VALUE
       Upon successful completion, the  mlockall()  function  shall  return  a
       value of zero. Otherwise, no additional memory shall be locked, and the
       function shall return a value of -1  and  set  errno  to  indicate  the
       error. The effect of failure of mlockall() on previously existing locks
       in the address space is unspecified.
       If it is supported by the  implementation,  the  munlockall()  function
       shall  always  return  a  value  of zero. Otherwise, the function shall
       return a value of -1 and set errno to indicate the error.
ERRORS
       The mlockall() function shall fail if:
       EAGAIN Some or all of the memory identified by the operation could  not
              be locked when the call was made.
       EINVAL The flags argument is zero, or includes unimplemented flags.

       The mlockall() function may fail if:
       ENOMEM Locking all of the pages currently mapped into the address space
              of the process 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(), mlock(), 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 Technology
       --  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                         MLOCKALL(3P)