1MLOCKALL(3P)               POSIX Programmer's Manual              MLOCKALL(3P)
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PROLOG

6       This  manual  page is part of the POSIX Programmer's Manual.  The Linux
7       implementation of this interface may differ (consult the  corresponding
8       Linux  manual page for details of Linux behavior), or the interface may
9       not be implemented on Linux.
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11

NAME

13       mlockall, munlockall — lock/unlock  the  address  space  of  a  process
14       (REALTIME)
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SYNOPSIS

17       #include <sys/mman.h>
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19       int mlockall(int flags);
20       int munlockall(void);
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DESCRIPTION

23       The  mlockall()  function  shall  cause  all of the pages mapped by the
24       address space of a process to  be  memory-resident  until  unlocked  or
25       until the process exits or execs another process image. The flags argu‐
26       ment determines whether the pages to  be  locked  are  those  currently
27       mapped  by  the  address space of the process, those that are mapped in
28       the future, or both. The flags argument is constructed  from  the  bit‐
29       wise-inclusive  OR  of one or more of the following symbolic constants,
30       defined in <sys/mman.h>:
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32       MCL_CURRENT Lock all of the pages currently  mapped  into  the  address
33                   space of the process.
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35       MCL_FUTURE  Lock  all  of the pages that become mapped into the address
36                   space of the process in the future, when those mappings are
37                   established.
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39       If  MCL_FUTURE  is  specified, and the automatic locking of future map‐
40       pings eventually causes the amount  of  locked  memory  to  exceed  the
41       amount of available physical memory or any other implementation-defined
42       limit, the behavior is implementation-defined. The manner in which  the
43       implementation  informs  the  application  of  these situations is also
44       implementation-defined.
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46       The munlockall() function shall unlock all currently  mapped  pages  of
47       the address space of the process. Any pages that become mapped into the
48       address space of the process after a call to munlockall() shall not  be
49       locked,  unless  there  is an intervening call to mlockall() specifying
50       MCL_FUTURE or a subsequent call to mlockall()  specifying  MCL_CURRENT.
51       If  pages  mapped into the address space of the process are also mapped
52       into the address spaces of other processes and are locked by those pro‐
53       cesses,  the  locks  established  by the other processes shall be unaf‐
54       fected by a call by this process to munlockall().
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56       Upon successful return from  the  mlockall()  function  that  specifies
57       MCL_CURRENT,  all  currently  mapped  pages of the address space of the
58       process shall be memory-resident and  locked.   Upon  return  from  the
59       munlockall()  function, all currently mapped pages of the address space
60       of the process shall be unlocked with respect to the address  space  of
61       the process.  The memory residency of unlocked pages is unspecified.
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63       Appropriate  privileges are required to lock process memory with mlock‐
64       all().
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RETURN VALUE

67       Upon successful completion, the  mlockall()  function  shall  return  a
68       value of zero. Otherwise, no additional memory shall be locked, and the
69       function shall return a value of −1  and  set  errno  to  indicate  the
70       error. The effect of failure of mlockall() on previously existing locks
71       in the address space is unspecified.
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73       If it is supported by the  implementation,  the  munlockall()  function
74       shall  always  return  a  value  of zero. Otherwise, the function shall
75       return a value of −1 and set errno to indicate the error.
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ERRORS

78       The mlockall() function shall fail if:
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80       EAGAIN Some or all of the memory identified by the operation could  not
81              be locked when the call was made.
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83       EINVAL The flags argument is zero, or includes unimplemented flags.
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85       The mlockall() function may fail if:
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87       ENOMEM Locking all of the pages currently mapped into the address space
88              of the process would exceed an implementation-defined  limit  on
89              the amount of memory that the process may lock.
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91       EPERM  The calling process does not have appropriate privileges to per‐
92              form the requested operation.
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94       The following sections are informative.
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EXAMPLES

97       None.
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APPLICATION USAGE

100       None.
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RATIONALE

103       None.
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FUTURE DIRECTIONS

106       None.
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SEE ALSO

109       exec, exit(), fork(), mlock(), munmap()
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111       The Base Definitions volume of POSIX.1‐2008, <sys_mman.h>
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114       Portions of this text are reprinted and reproduced in  electronic  form
115       from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
116       -- Portable Operating System Interface (POSIX),  The  Open  Group  Base
117       Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri‐
118       cal and Electronics Engineers,  Inc  and  The  Open  Group.   (This  is
119       POSIX.1-2008  with  the  2013  Technical Corrigendum 1 applied.) In the
120       event of any discrepancy between this version and the original IEEE and
121       The  Open Group Standard, the original IEEE and The Open Group Standard
122       is the referee document. The original Standard can be  obtained  online
123       at http://www.unix.org/online.html .
124
125       Any  typographical  or  formatting  errors that appear in this page are
126       most likely to have been introduced during the conversion of the source
127       files  to  man page format. To report such errors, see https://www.ker
128       nel.org/doc/man-pages/reporting_bugs.html .
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132IEEE/The Open Group                  2013                         MLOCKALL(3P)
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