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mlock(2)							      mlock(2)

NAME
       mlock() - lock a segment of the process virtual address space in memory

SYNOPSIS
DESCRIPTION
       The  system  call  allows  the calling process to lock a segment of the
       process virtual address space into memory.  Any addressable segment  of
       the  process'  address space may be locked.  Locked segments are immune
       to all routine swapping.

       addr must be a valid address in	the  process  virtual  address	space.
       addr  + len must also be a valid address in the process virtual address
       space.

       Locks are applied at page boundaries that encompass the range from addr
       to  addr + len.	If any address within the range is not valid, an error
       is returned and no locks are applied.

       or can be used to unlock	 memory	 segments  (or	all  memory  segments)
       locked with

       Regardless  of  how many times a process locks a page, a single or will
       unlock it.  An of a page within a range specified in an call results in
       only the range specified in the being unlocked.

       When  memory  is shared by multiple processes and mlocks are applied to
       the same physical page by multiple processes,  a	 page  remains	locked
       until the last lock is removed from that page.

       Locks applied with are not inherited by a child process.

       The user must have the privilege.

       Although	 and the family of functions may be used together in an appli‐
       cation, each may affect the other in unexpected ways.  This practice is
       not recommended.

   Security Restrictions
       Some or all of the actions associated with this system call require the
       privilege.  Processes owned by the superuser have this privilege.  Pro‐
       cesses  owned by other users may have this privilege, depending on sys‐
       tem configuration.  See privileges(5) for more information about privi‐
       leged access on systems that support fine-grained privileges.

RETURN VALUE
       returns the following values:

	      Successful completion.
	      Failure.
		     The  requested  operation	is  not	 performed.  is set to
		     indicate the error.

ERRORS
       If fails, is set to one of the following values:

	      One or more addresses in the specified range is not valid within
			     the process address space.

	      There is not enough lockable memory in the system
			     to satisfy the locking request.

	      The	     parameter was zero.

	      The user does not have the
			     privilege.

EXAMPLES
       The following call to locks the first 10 pages of the  calling  process
       in memory:

SEE ALSO
       setprivgrp(1M),	getprivgrp(2), mlockall(2), munlock(2), munlockall(2),
       plock(2), privileges(5).

STANDARDS CONFORMANCE
								      mlock(2)

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