mirror of https://github.com/mkerrisk/man-pages
These are now just links; their content has been consoldiated intomlock.2
This commit is contained in:
parent
8176b81ab6
commit
8ce20bf7ba
171
man2/mlockall.2
171
man2/mlockall.2
|
@ -1,170 +1 @@
|
||||||
.\" Hey Emacs! This file is -*- nroff -*- source.
|
.so man2/mlock.2
|
||||||
.\"
|
|
||||||
.\" Copyright (C) Markus Kuhn, 1996
|
|
||||||
.\"
|
|
||||||
.\" This is free documentation; you can redistribute it and/or
|
|
||||||
.\" modify it under the terms of the GNU General Public License as
|
|
||||||
.\" published by the Free Software Foundation; either version 2 of
|
|
||||||
.\" the License, or (at your option) any later version.
|
|
||||||
.\"
|
|
||||||
.\" The GNU General Public License's references to "object code"
|
|
||||||
.\" and "executables" are to be interpreted as the output of any
|
|
||||||
.\" document formatting or typesetting system, including
|
|
||||||
.\" intermediate and printed output.
|
|
||||||
.\"
|
|
||||||
.\" This manual is distributed in the hope that it will be useful,
|
|
||||||
.\" but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
||||||
.\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
||||||
.\" GNU General Public License for more details.
|
|
||||||
.\"
|
|
||||||
.\" You should have received a copy of the GNU General Public
|
|
||||||
.\" License along with this manual; if not, write to the Free
|
|
||||||
.\" Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111,
|
|
||||||
.\" USA.
|
|
||||||
.\"
|
|
||||||
.\" 1995-11-26 Markus Kuhn <mskuhn@cip.informatik.uni-erlangen.de>
|
|
||||||
.\" First version written
|
|
||||||
.\" Modified, 27 May 2004, Michael Kerrisk <mtk-manpages@gmx.net>
|
|
||||||
.\" Added notes on capability requirements
|
|
||||||
.\" Modified, 2004-11-23, mtk, Noted buggy MCL_FUTURE behaviour in 2.4.x
|
|
||||||
.\" Modified, 2004-11-25, mtk, 2.4 limits locks to half of physical mem.
|
|
||||||
.\" Modified, 2004-11-25, mtk, Noted MCL_FUTURE bug in 2.4.x, x < 18
|
|
||||||
.\"
|
|
||||||
.TH MLOCKALL 2 2004-11-25 "Linux 2.6.9" "Linux Programmer's Manual"
|
|
||||||
.SH NAME
|
|
||||||
mlockall \- disable paging for calling process
|
|
||||||
.SH SYNOPSIS
|
|
||||||
.nf
|
|
||||||
.B #include <sys/mman.h>
|
|
||||||
.sp
|
|
||||||
\fBint mlockall(int \fIflags\fB);
|
|
||||||
.fi
|
|
||||||
.SH DESCRIPTION
|
|
||||||
.B mlockall
|
|
||||||
disables paging for all pages mapped into the address space of the
|
|
||||||
calling process. This includes the pages of the code, data and stack
|
|
||||||
segment, as well as shared libraries, user space kernel data, shared
|
|
||||||
memory and memory mapped files. All mapped pages are guaranteed to be
|
|
||||||
resident in RAM when the
|
|
||||||
.B mlockall
|
|
||||||
system call returns successfully and they are guaranteed to stay in RAM
|
|
||||||
until the pages are unlocked again by
|
|
||||||
.B munlock
|
|
||||||
or
|
|
||||||
.B munlockall
|
|
||||||
or until the process terminates or starts another program with
|
|
||||||
.BR exec .
|
|
||||||
Child processes do not inherit page locks across a
|
|
||||||
.BR fork .
|
|
||||||
|
|
||||||
Memory locking has two main applications: real-time algorithms and
|
|
||||||
high-security data processing. Real-time applications require
|
|
||||||
deterministic timing, and, like scheduling, paging is one major cause
|
|
||||||
of unexpected program execution delays. Real-time applications will
|
|
||||||
usually also switch to a real-time scheduler with
|
|
||||||
.BR sched_setscheduler .
|
|
||||||
Cryptographic security software often handles critical bytes like
|
|
||||||
passwords or secret keys as data structures. As a result of paging,
|
|
||||||
these secrets could be transfered onto a persistent swap store medium,
|
|
||||||
where they might be accessible to the enemy long after the security
|
|
||||||
software has erased the secrets in RAM and terminated. For security
|
|
||||||
applications, only small parts of memory have to be locked, for which
|
|
||||||
.B mlock
|
|
||||||
is available.
|
|
||||||
|
|
||||||
The
|
|
||||||
.I flags
|
|
||||||
parameter can be constructed from the bitwise OR of the following
|
|
||||||
constants:
|
|
||||||
.TP 1.2i
|
|
||||||
.B MCL_CURRENT
|
|
||||||
Lock all pages which are currently mapped into the address space of
|
|
||||||
the process.
|
|
||||||
.TP
|
|
||||||
.B MCL_FUTURE
|
|
||||||
Lock all pages which will become mapped into the address space of the
|
|
||||||
process in the future. These could be for instance new pages required
|
|
||||||
by a growing heap and stack as well as new memory mapped files or
|
|
||||||
shared memory regions.
|
|
||||||
.PP
|
|
||||||
If
|
|
||||||
.B MCL_FUTURE
|
|
||||||
has been specified and the number of locked pages exceeds the upper
|
|
||||||
limit of allowed locked pages, then the system call which caused the
|
|
||||||
new mapping will fail with
|
|
||||||
.BR ENOMEM .
|
|
||||||
If these new pages have been mapped by the the growing stack, then the
|
|
||||||
kernel will deny stack expansion and send a
|
|
||||||
.BR SIGSEGV .
|
|
||||||
|
|
||||||
Real-time processes should reserve enough locked stack pages before
|
|
||||||
entering the time-critical section, so that no page fault can be
|
|
||||||
caused by function calls. This can be achieved by calling a function
|
|
||||||
which has a sufficiently large automatic variable and which writes to
|
|
||||||
the memory occupied by this large array in order to touch these stack
|
|
||||||
pages. This way, enough pages will be mapped for the stack and can be
|
|
||||||
locked into RAM. The dummy writes ensure that not even copy-on-write
|
|
||||||
page faults can occur in the critical section.
|
|
||||||
|
|
||||||
Memory locks do not stack, i.e., pages which have been locked several times
|
|
||||||
by calls to
|
|
||||||
.B mlockall
|
|
||||||
or
|
|
||||||
.B mlock
|
|
||||||
will be unlocked by a single call to
|
|
||||||
.BR munlockall .
|
|
||||||
Pages which are mapped to several locations or by several processes stay
|
|
||||||
locked into RAM as long as they are locked at least at one location or by
|
|
||||||
at least one process.
|
|
||||||
.SH "NOTES"
|
|
||||||
In Linux 2.4 and earlier, the kernel prevents a single process
|
|
||||||
from locking more than half of RAM.
|
|
||||||
.SH "RETURN VALUE"
|
|
||||||
On success,
|
|
||||||
.B mlockall
|
|
||||||
returns zero. On error, \-1 is returned, and
|
|
||||||
.I errno
|
|
||||||
is set appropriately.
|
|
||||||
.SH ERRORS
|
|
||||||
.TP
|
|
||||||
.B EINVAL
|
|
||||||
Unknown flags were specified.
|
|
||||||
.TP
|
|
||||||
.B ENOMEM
|
|
||||||
The process tried to exceed the maximum number of allowed locked
|
|
||||||
pages.
|
|
||||||
.TP
|
|
||||||
.B EPERM
|
|
||||||
The calling process has insufficient privilege to call
|
|
||||||
.BR mlockall .
|
|
||||||
Under Linux the
|
|
||||||
.B CAP_IPC_LOCK
|
|
||||||
capability is required.
|
|
||||||
.SH "BUGS"
|
|
||||||
In the 2.4 series Linux kernels up to and including 2.4.17,
|
|
||||||
a bug caused the
|
|
||||||
.B MCL_FUTURE
|
|
||||||
flag to be inherited across a
|
|
||||||
.BR fork (2).
|
|
||||||
This was rectified in kernel 2.4.18.
|
|
||||||
.SH AVAILABILITY
|
|
||||||
On POSIX systems on which
|
|
||||||
.B mlockall
|
|
||||||
and
|
|
||||||
.B munlockall
|
|
||||||
are available,
|
|
||||||
.B _POSIX_MEMLOCK
|
|
||||||
is defined in <unistd.h> to a value greater than 0. (See also
|
|
||||||
.BR sysconf (3).)
|
|
||||||
.\" POSIX 1003.1-2001: It shall be defined to -1 or 0 or 200112L.
|
|
||||||
.\" -1: unavailable, 0: ask using sysconf().
|
|
||||||
.\" glibc defines it to 1.
|
|
||||||
.SH "CONFORMING TO"
|
|
||||||
POSIX.1b, SVr4. SVr4 documents an additional EAGAIN error code.
|
|
||||||
.SH "SEE ALSO"
|
|
||||||
.BR mlock (2),
|
|
||||||
.BR munlock (2),
|
|
||||||
.BR munlockall (2),
|
|
||||||
.BR setrlimit (2),
|
|
||||||
.BR sysconf (3),
|
|
||||||
.BR capabilities (7)
|
|
||||||
|
|
|
@ -1,98 +1 @@
|
||||||
.\" Hey Emacs! This file is -*- nroff -*- source.
|
.so man2/mlock.2
|
||||||
.\"
|
|
||||||
.\" Copyright (C) Markus Kuhn, 1996
|
|
||||||
.\"
|
|
||||||
.\" This is free documentation; you can redistribute it and/or
|
|
||||||
.\" modify it under the terms of the GNU General Public License as
|
|
||||||
.\" published by the Free Software Foundation; either version 2 of
|
|
||||||
.\" the License, or (at your option) any later version.
|
|
||||||
.\"
|
|
||||||
.\" The GNU General Public License's references to "object code"
|
|
||||||
.\" and "executables" are to be interpreted as the output of any
|
|
||||||
.\" document formatting or typesetting system, including
|
|
||||||
.\" intermediate and printed output.
|
|
||||||
.\"
|
|
||||||
.\" This manual is distributed in the hope that it will be useful,
|
|
||||||
.\" but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
||||||
.\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
||||||
.\" GNU General Public License for more details.
|
|
||||||
.\"
|
|
||||||
.\" You should have received a copy of the GNU General Public
|
|
||||||
.\" License along with this manual; if not, write to the Free
|
|
||||||
.\" Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111,
|
|
||||||
.\" USA.
|
|
||||||
.\"
|
|
||||||
.\" 1995-11-26 Markus Kuhn <mskuhn@cip.informatik.uni-erlangen.de>
|
|
||||||
.\" First version written
|
|
||||||
.\"
|
|
||||||
.TH MUNLOCK 2 2003-08-21 "Linux 2.4" "Linux Programmer's Manual"
|
|
||||||
.SH NAME
|
|
||||||
munlock \- reenable paging for some parts of memory
|
|
||||||
.SH SYNOPSIS
|
|
||||||
.nf
|
|
||||||
.B #include <sys/mman.h>
|
|
||||||
.sp
|
|
||||||
\fBint munlock(const void *\fIaddr\fB, size_t \fIlen\fB);
|
|
||||||
.fi
|
|
||||||
.SH DESCRIPTION
|
|
||||||
.B munlock
|
|
||||||
reenables paging for the memory in the range starting at
|
|
||||||
.I addr
|
|
||||||
with length
|
|
||||||
.I len
|
|
||||||
bytes. All pages which contain a part of the specified memory range
|
|
||||||
can after calling
|
|
||||||
.B munlock
|
|
||||||
be moved to external swap space again by the kernel.
|
|
||||||
|
|
||||||
Memory locks do not stack, i.e., pages which have been locked several times
|
|
||||||
by calls to
|
|
||||||
.B mlock
|
|
||||||
or
|
|
||||||
.B mlockall
|
|
||||||
will be unlocked by a single call to
|
|
||||||
.B munlock
|
|
||||||
for the corresponding range or by
|
|
||||||
.BR munlockall .
|
|
||||||
Pages which are mapped to several locations or by several processes stay
|
|
||||||
locked into RAM as long as they are locked at least at one location or by
|
|
||||||
at least one process.
|
|
||||||
|
|
||||||
On POSIX systems on which
|
|
||||||
.B mlock
|
|
||||||
and
|
|
||||||
.B munlock
|
|
||||||
are available,
|
|
||||||
.B _POSIX_MEMLOCK_RANGE
|
|
||||||
is defined in <unistd.h> and the value
|
|
||||||
.B PAGESIZE
|
|
||||||
from <limits.h> indicates the number of bytes per page.
|
|
||||||
.SH "RETURN VALUE"
|
|
||||||
On success,
|
|
||||||
.B munlock
|
|
||||||
returns zero. On error, \-1 is returned,
|
|
||||||
.I errno
|
|
||||||
is set appropriately, and no changes are made to any locks in the
|
|
||||||
address space of the process.
|
|
||||||
.SH ERRORS
|
|
||||||
.TP
|
|
||||||
.B EINVAL
|
|
||||||
(Not on Linux)
|
|
||||||
.I addr
|
|
||||||
was not a multiple of the page size.
|
|
||||||
.TP
|
|
||||||
.B ENOMEM
|
|
||||||
Some of the specified address range does not correspond to mapped
|
|
||||||
pages in the address space of the process.
|
|
||||||
.LP
|
|
||||||
Linux adds
|
|
||||||
.TP
|
|
||||||
.B EINVAL
|
|
||||||
.I len
|
|
||||||
was negative.
|
|
||||||
.SH "CONFORMING TO"
|
|
||||||
POSIX.1b, SVr4
|
|
||||||
.SH "SEE ALSO"
|
|
||||||
.BR mlock (2),
|
|
||||||
.BR mlockall (2),
|
|
||||||
.BR munlockall (2)
|
|
||||||
|
|
|
@ -1,86 +1 @@
|
||||||
.\" Hey Emacs! This file is -*- nroff -*- source.
|
.so man2/mlock.2
|
||||||
.\"
|
|
||||||
.\" Copyright (C) Markus Kuhn, 1996
|
|
||||||
.\"
|
|
||||||
.\" This is free documentation; you can redistribute it and/or
|
|
||||||
.\" modify it under the terms of the GNU General Public License as
|
|
||||||
.\" published by the Free Software Foundation; either version 2 of
|
|
||||||
.\" the License, or (at your option) any later version.
|
|
||||||
.\"
|
|
||||||
.\" The GNU General Public License's references to "object code"
|
|
||||||
.\" and "executables" are to be interpreted as the output of any
|
|
||||||
.\" document formatting or typesetting system, including
|
|
||||||
.\" intermediate and printed output.
|
|
||||||
.\"
|
|
||||||
.\" This manual is distributed in the hope that it will be useful,
|
|
||||||
.\" but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
||||||
.\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
||||||
.\" GNU General Public License for more details.
|
|
||||||
.\"
|
|
||||||
.\" You should have received a copy of the GNU General Public
|
|
||||||
.\" License along with this manual; if not, write to the Free
|
|
||||||
.\" Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111,
|
|
||||||
.\" USA.
|
|
||||||
.\"
|
|
||||||
.\" 1995-11-26 Markus Kuhn <mskuhn@cip.informatik.uni-erlangen.de>
|
|
||||||
.\" First version written
|
|
||||||
.\" Modified, 27 May 2004, Michael Kerrisk <mtk-manpages@gmx.net>
|
|
||||||
.\" Added notes on capability requirements
|
|
||||||
.\"
|
|
||||||
.TH MUNLOCKALL 2 2004-05-27 "Linux 2.6.6" "Linux Programmer's Manual"
|
|
||||||
.SH NAME
|
|
||||||
munlockall \- reenable paging for calling process
|
|
||||||
.SH SYNOPSIS
|
|
||||||
.nf
|
|
||||||
.B #include <sys/mman.h>
|
|
||||||
.sp
|
|
||||||
\fBint munlockall(void);
|
|
||||||
.fi
|
|
||||||
.SH DESCRIPTION
|
|
||||||
.B munlockall
|
|
||||||
reenables paging for all pages mapped into the address space of the
|
|
||||||
calling process.
|
|
||||||
|
|
||||||
Memory locks do not stack, i.e., pages which have been locked several times
|
|
||||||
by calls to
|
|
||||||
.B mlock
|
|
||||||
or
|
|
||||||
.B mlockall
|
|
||||||
will be unlocked by a single call to
|
|
||||||
.BR munlockall .
|
|
||||||
Pages which are mapped to several locations or by several processes stay
|
|
||||||
locked into RAM as long as they are locked at least at one location or by
|
|
||||||
at least one process.
|
|
||||||
|
|
||||||
On POSIX systems on which
|
|
||||||
.B mlockall
|
|
||||||
and
|
|
||||||
.B munlockall
|
|
||||||
are available,
|
|
||||||
.B _POSIX_MEMLOCK
|
|
||||||
is defined in
|
|
||||||
.I <unistd.h> .
|
|
||||||
.SH "RETURN VALUE"
|
|
||||||
On success,
|
|
||||||
.B munlockall
|
|
||||||
returns zero. On error, \-1 is returned and
|
|
||||||
.I errno
|
|
||||||
is set appropriately.
|
|
||||||
.SH ERRORS
|
|
||||||
.TP
|
|
||||||
.B EPERM
|
|
||||||
The calling process has insufficient privilege to call
|
|
||||||
.BR munlockall .
|
|
||||||
Under Linux the
|
|
||||||
.B CAP_IPC_LOCK
|
|
||||||
capability is required.
|
|
||||||
.\" Weirdness this way comes: CAP_IPC_LOCK is required for munlockall()
|
|
||||||
.\" and shmctl(SHM_UNLOCK), but is *not* required for munlock
|
|
||||||
.\" (as at kernel 2.6.6)
|
|
||||||
.SH "CONFORMING TO"
|
|
||||||
POSIX.1b, SVr4
|
|
||||||
.SH "SEE ALSO"
|
|
||||||
.BR mlock (2),
|
|
||||||
.BR mlockall (2),
|
|
||||||
.BR munlock (2),
|
|
||||||
.BR capabilities (7)
|
|
||||||
|
|
Loading…
Reference in New Issue