$NetBSD: mlockall.2,v 1.11 2003/04/16 13:34:54 wiz Exp $ Copyright (c) 1999 The NetBSD Foundation, Inc. All rights reserved. This code is derived from software contributed to The NetBSD Foundation by Jason R. Thorpe of the Numerical Aerospace Simulation Facility, NASA Ames Research Center. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: 1. Redistributions of source code must retain the ...
NAMEmlockall munlockall - lock (unlock) the address space of a process
SYNOPSISIn sys/mman.h Ft int Fn mlockall int flags Ft int Fn munlockall void
DESCRIPTIONThe Fn 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 Fn mlockall :
- Lock all pages currently mapped into the process's address space.
- 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 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 Fn mlockall calls.
The Fn munlockall call unlocks any locked memory regions in the process address space. Any regions mapped after an Fn munlockall call will not be locked.
RETURN VALUESA 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.
ERRORSFn mlockall will fail if:
- Bq Er EINVAL
- The Fa flags argument is zero, or includes unimplemented flags.
- Bq Er ENOMEM
- Locking the indicated range would exceed either the system or per-process limit for locked memory.
- Bq Er EAGAIN
- Some or all of the memory mapped into the process's address space could not be locked when the call was made.
- Bq Er EPERM
- The calling process does not have the appropriate privilege to perform the requested operation.