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MLOCKALL(2)		  FreeBSD 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
     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 vm.max_wired and the per-
     process 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
     The mlockall() and	munlockall() functions are believed to conform to IEEE
     Std 1003.1-2001 (``POSIX.1'').

HISTORY
     The mlockall() 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.

FreeBSD	10.1		       December	25, 2012		  FreeBSD 10.1

NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUES | ERRORS | SEE ALSO | STANDARDS | HISTORY | BUGS

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