unixdev.net


Switch to SpeakEasy.net DSL

The Modular Manual Browser

Home Page
Manual: (OpenBSD-5.7)
Page:
Section:
Apropos / Subsearch:
optional field

MLOCKALL(2)                 BSD System Calls Manual                MLOCKALL(2)

NAME
     mlockall, munlockall -- lock (unlock) the address space of a process

SYNOPSIS
     #include <&lt;sys/mman.h>&gt;

     int
     mlockall(int flags);

     int
     munlockall(void);

DESCRIPTION
     The mlockall() system call locks into memory the physical pages associ-
     ated with the address space of a process until the address space is
     unlocked, the process exits, or execs another program image.

     The following flags affect the behavior of mlockall():

     MCL_CURRENT  Lock all pages currently mapped into the process's address
                  space.

     MCL_FUTURE   Lock all pages mapped into the process's address space in
                  the future, at the time the mapping is established.  Note
                  that this may cause future mappings to fail if those map-
                  pings cause resource limits to be exceeded.

     Since physical memory is a potentially scarce resource, processes are
     limited in how much they can lock down.  A single process can lock the
     minimum of a system-wide ``wired pages'' limit and the per-process
     RLIMIT_MEMLOCK resource limit.

     The munlockall() call unlocks any locked memory regions in the process
     address space.  Any regions mapped after an munlockall() call will not be
     locked.

RETURN VALUES
     The mlockall() and munlockall() functions return the value 0 if success-
     ful; otherwise the value -1 is returned and the global variable errno is
     set to indicate the error.

ERRORS
     mlockall() will fail if:

     [EINVAL]           The flags argument is zero or includes unimplemented
                        flags.

     [ENOMEM]           Locking all of the pages currently mapped would exceed
                        either the system or per-process limit for locked mem-
                        ory.

     [EAGAIN]           Some or all of the memory mapped into the process's
                        address space could not be locked when the call was
                        made.

     [EPERM]            The calling process does not have the appropriate
                        privileges to perform the requested operation.

SEE ALSO
     mincore(2), mlock(2), mmap(2), munmap(2), setrlimit(2)

STANDARDS
     The mlockall() and munlockall() functions conform to IEEE Std 1003.1-2008
     (``POSIX.1'').

HISTORY
     The mlockall() and munlockall() functions first appeared in OpenBSD 2.9.

BUGS
     The per-process resource limit is a limit on the amount of virtual memory
     locked, while the system-wide limit is for the number of locked physical
     pages.  Hence a process with two distinct locked mappings of the same
     physical page counts as 2 pages against the per-process limit and only as
     a single page in the system limit.

BSD                              May 28, 2017                              BSD