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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
     The  mlockall() 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.

     Since physical memory is a potentially scarce resource, processes are  lim-
     ited in how much they can lock down.  A single process can lock the minimum
     of  a system-wide "wired pages" limit vm.max_user_wired and the per-process
     RLIMIT_MEMLOCK resource limit.

     If security.bsd.unprivileged_mlock is set to 0 these calls are only  avail-
     able  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  ad-
     dress  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 sys-
			tem or per-process limit for locked memory.

     [EAGAIN]		Some  or all of the memory mapped into the process's ad-
			dress space could not be locked when the call was made.

     [EPERM]		The calling process does not have the appropriate privi-
			lege 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  and system-wide resource limits of locked memory apply to
     the amount of virtual memory locked, not  the  amount  of	locked	physical
     pages.  Hence two distinct locked mappings of the same physical page counts
     as  2 pages aginst the system limit, and also against the per-process limit
     if both mappings belong to the same physical map.

FreeBSD ports 15.quarterly	  May 13, 2019			     MLOCKALL(2)

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