mlockall, munlockall - lock or unlock address space
int mlockall(int flags);
The mlockall() function locks in memory all pages mapped by
an address space.
The value of flags determines whether the pages to be locked
are those currently mapped by the address space, those that
will be mapped in the future, or both:
MCL_CURRENT Lock current mappings
MCL_FUTURE Lock future mappings
If MCL_FUTURE is specified for mlockall(), mappings are
locked as they are added to the address space (or replace
existing mappings), provided sufficient memory is available.
Locking in this manner is not persistent across the exec
family of functions (see exec(2)).
Mappings locked using mlockall() with any option may be
explicitly unlocked with a munlock() call (see mlock(3C)).
The munlockall() function removes address space locks and
locks on mappings in the address space.
All conditions and constraints on the use of locked memory
that apply to mlock(3C) also apply to mlockall().
Locks established with mlockall() are not inherited by a
child process after a fork(2) call, and are not nested.
Upon successful completion, the mlockall() and munlock-
all() functions return 0. Otherwise, they return -1 and
set errno to indicate the error.
The mlockall() and munlockall() functions will fail if:
Some or all of the memory in the address space could
not be locked due to sufficient resources. This error
condition applies to mlockall() only.
The flags argument contains values other than
MCL_CURRENT and MCL_FUTURE.
EPERM The process's effective user ID is not super-user.
The mlockall() and munlockall() functions require super-user
See attributes(5) for descriptions of the following attri-
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
| MT-Level | MT-Safe |
exec(2), fork(2), memcntl(2), mmap(2), plock(3C), mlock(3C),
Man(1) output converted with