1MLOCKALL(3P) POSIX Programmer's Manual MLOCKALL(3P)
2
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.
10
12 mlockall, munlockall — lock/unlock the address space of a process
13 (REALTIME)
14
16 #include <sys/mman.h>
17 int mlockall(int flags);
19 int munlockall(void);
20
22 The mlockall() function shall cause all of the pages mapped by the
23 address space of a process to be memory-resident until unlocked or
24 until the process exits or execs another process image. The flags argu‐
25 ment determines whether the pages to be locked are those currently
26 mapped by the address space of the process, those that are mapped in
27 the future, or both. The flags argument is constructed from the bit‐
28 wise-inclusive OR of one or more of the following symbolic constants,
29 defined in <sys/mman.h>:
30 MCL_CURRENT Lock all of the pages currently mapped into the address
32 space of the process.
33 MCL_FUTURE Lock all of the pages that become mapped into the address
35 space of the process in the future, when those mappings are
36 established.
37 If MCL_FUTURE is specified, and the automatic locking of future map‐
39 pings eventually causes the amount of locked memory to exceed the
40 amount of available physical memory or any other implementation-defined
41 limit, the behavior is implementation-defined. The manner in which the
42 implementation informs the application of these situations is also
43 implementation-defined.
44 The munlockall() function shall unlock all currently mapped pages of
46 the address space of the process. Any pages that become mapped into the
47 address space of the process after a call to munlockall() shall not be
48 locked, unless there is an intervening call to mlockall() specifying
49 MCL_FUTURE or a subsequent call to mlockall() specifying MCL_CURRENT.
50 If pages mapped into the address space of the process are also mapped
51 into the address spaces of other processes and are locked by those pro‐
52 cesses, the locks established by the other processes shall be unaf‐
53 fected by a call by this process to munlockall().
54 Upon successful return from the mlockall() function that specifies
56 MCL_CURRENT, all currently mapped pages of the address space of the
57 process shall be memory-resident and locked. Upon return from the
58 munlockall() function, all currently mapped pages of the address space
59 of the process shall be unlocked with respect to the address space of
60 the process. The memory residency of unlocked pages is unspecified.
61 Appropriate privileges are required to lock process memory with mlock‐
63 all().
64
66 Upon successful completion, the mlockall() function shall return a
67 value of zero. Otherwise, no additional memory shall be locked, and the
68 function shall return a value of -1 and set errno to indicate the
69 error. The effect of failure of mlockall() on previously existing locks
70 in the address space is unspecified.
71 If it is supported by the implementation, the munlockall() function
73 shall always return a value of zero. Otherwise, the function shall
74 return a value of -1 and set errno to indicate the error.
75
77 The mlockall() function shall fail if:
78 EAGAIN Some or all of the memory identified by the operation could not
80 be locked when the call was made.
81 EINVAL The flags argument is zero, or includes unimplemented flags.
83 The mlockall() function may fail if:
85 ENOMEM Locking all of the pages currently mapped into the address space
87 of the process would exceed an implementation-defined limit on
88 the amount of memory that the process may lock.
89 EPERM The calling process does not have appropriate privileges to per‐
91 form the requested operation.
92 The following sections are informative.
94
96 None.
97
99 None.
100
102 None.
103
105 None.
106
108 exec, exit(), fork(), mlock(), munmap()
109 The Base Definitions volume of POSIX.1‐2017, <sys_mman.h>
111
113 Portions of this text are reprinted and reproduced in electronic form
114 from IEEE Std 1003.1-2017, Standard for Information Technology -- Por‐
115 table Operating System Interface (POSIX), The Open Group Base Specifi‐
116 cations Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of
117 Electrical and Electronics Engineers, Inc and The Open Group. In the
118 event of any discrepancy between this version and the original IEEE and
119 The Open Group Standard, the original IEEE and The Open Group Standard
120 is the referee document. The original Standard can be obtained online
121 at http://www.opengroup.org/unix/online.html .
122 Any typographical or formatting errors that appear in this page are
124 most likely to have been introduced during the conversion of the source
125 files to man page format. To report such errors, see https://www.ker‐
126 nel.org/doc/man-pages/reporting_bugs.html .
127IEEE/The Open Group 2017 MLOCKALL(3P)