147 lines
4.5 KiB
Groff
147 lines
4.5 KiB
Groff
.\" $NetBSD: mlockall.2,v 1.11 2003/04/16 13:34:54 wiz Exp $
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.\"
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.\" Copyright (c) 1999 The NetBSD Foundation, Inc.
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.\" All rights reserved.
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.\"
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.\" This code is derived from software contributed to The NetBSD Foundation
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.\" by Jason R. Thorpe of the Numerical Aerospace Simulation Facility,
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.\" NASA Ames Research Center.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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.\" POSSIBILITY OF SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd December 25, 2012
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.Dt MLOCKALL 2
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.Os
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.Sh NAME
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.Nm mlockall ,
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.Nm munlockall
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.Nd lock (unlock) the address space of a process
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In sys/mman.h
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.Ft int
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.Fn mlockall "int flags"
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.Ft int
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.Fn munlockall "void"
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.Sh DESCRIPTION
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The
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.Fn mlockall
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system call locks into memory the physical pages associated with the
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address space of a process until the address space is unlocked, the
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process exits, or execs another program image.
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.Pp
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The following flags affect the behavior of
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.Fn mlockall :
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.Bl -tag -width ".Dv MCL_CURRENT"
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.It Dv MCL_CURRENT
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Lock all pages currently mapped into the process's address space.
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.It Dv MCL_FUTURE
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Lock all pages mapped into the process's address space in the future,
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at the time the mapping is established.
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Note that this may cause future mappings to fail if those mappings
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cause resource limits to be exceeded.
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.El
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.Pp
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Since physical memory is a potentially scarce resource, processes are
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limited in how much they can lock down.
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A single process can lock the minimum of a system-wide
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.Dq wired pages
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limit
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.Va vm.max_wired
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and the per-process
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.Dv RLIMIT_MEMLOCK
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resource limit.
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.Pp
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If
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.Va security.bsd.unprivileged_mlock
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is set to 0 these calls are only available to the super-user.
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If
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.Va vm.old_mlock
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is set to 1 the per-process
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.Dv RLIMIT_MEMLOCK
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resource limit will not be applied for
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.Fn mlockall
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calls.
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.Pp
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The
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.Fn munlockall
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call unlocks any locked memory regions in the process address space.
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Any regions mapped after an
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.Fn munlockall
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call will not be locked.
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.Sh RETURN VALUES
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A return value of 0 indicates that the call
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succeeded and all pages in the range have either been locked or unlocked.
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A return value of \-1 indicates an error occurred and the locked
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status of all pages in the range remains unchanged.
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In this case, the global location
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.Va errno
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is set to indicate the error.
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.Sh ERRORS
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.Fn mlockall
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will fail if:
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.Bl -tag -width Er
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.It Bq Er EINVAL
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The
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.Fa flags
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argument is zero, or includes unimplemented flags.
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.It Bq Er ENOMEM
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Locking the indicated range would exceed either the system or per-process
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limit for locked memory.
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.It Bq Er EAGAIN
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Some or all of the memory mapped into the process's address space
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could not be locked when the call was made.
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.It Bq Er EPERM
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The calling process does not have the appropriate privilege to perform
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the requested operation.
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.El
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.Sh SEE ALSO
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.Xr mincore 2 ,
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.Xr mlock 2 ,
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.Xr mmap 2 ,
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.Xr munmap 2 ,
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.Xr setrlimit 2
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.Sh STANDARDS
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The
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.Fn mlockall
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and
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.Fn munlockall
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functions are believed to conform to
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.St -p1003.1-2001 .
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.Sh HISTORY
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The
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.Fn mlockall
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and
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.Fn munlockall
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functions first appeared in
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.Fx 5.1 .
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.Sh BUGS
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The per-process resource limit is a limit on the amount of virtual
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memory locked, while the system-wide limit is for the number of locked
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physical pages.
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Hence a process with two distinct locked mappings of the same physical page
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counts as 2 pages against the per-process limit and as only a single page
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in the system limit.
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