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MLOCKALL(2)		  FreeBSD System Calls Manual		   MLOCKALL(2)

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

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 un-
     locked, 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
     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.

FreeBSD	13.0		       January 11, 2019			  FreeBSD 13.0

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

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