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 argument
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 bitwise-inclusive OR of one
or more of the following symbolic constants, defined in
Lock all of the pages currently mapped into the address
space of the process.
Lock all of the pages that become mapped into the address
space of the process in the future, when those mappings are established.
If MCL_FUTURE is specified, and the automatic locking of future mappings
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 processes, the locks
established by the other processes shall be unaffected 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 memory residency of unlocked
pages is unspecified.
The appropriate privilege is required to lock process memory with
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.
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