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MLOCKALL(2) | System Calls Manual | MLOCKALL(2) |
NAME¶
mlockall
,
munlockall
—
lock (unlock) the address space of a process
LIBRARY¶
Standard C Library (libc, -lc)SYNOPSIS¶
#include
<sys/mman.h>
int
mlockall
(int
flags);
int
munlockall
(void);
DESCRIPTION¶
Themlockall
() system call locks into memory
the physical pages associated 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 mappings cause resource limits to be exceeded.
RLIMIT_MEMLOCK
resource limit.
If security.bsd.unprivileged_mlock is set to 0
these calls are only available to the super-user. If
vm.old_mlock is set to 1 the per-process
RLIMIT_MEMLOCK
resource limit will not be
applied for mlockall
() calls.
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¶
A return value of 0 indicates that the call succeeded and all pages in the range have either been locked or unlocked. A return value of -1 indicates an error occurred and the locked status of all pages in the range remains unchanged. In this case, the global location errno is set to indicate the error.ERRORS¶
mlockall
() will fail if:
- [
EINVAL
] - The flags argument is zero, or includes unimplemented flags.
- [
ENOMEM
] - Locking the indicated range would exceed either the system or per-process limit for locked memory.
- [
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 privilege to perform the requested operation.
SEE ALSO¶
mincore(2), mlock(2), mmap(2), munmap(2), setrlimit(2)STANDARDS¶
Themlockall
() and
munlockall
() functions are believed to
conform to IEEE Std 1003.1-2001
(“POSIX.1”).
HISTORY¶
Themlockall
() and
munlockall
() functions first appeared in
FreeBSD 5.1.
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 as only a single page in the system limit.December 25, 2012 | Debian |