int
mlock(
void *addr
, size_t len
)
int
munlock(
void *addr
, size_t len
)
addr
for
len
bytes.
The
munlock
call unlocks pages previously locked by one or more
mlock
calls.
For both, the
addr
parameter should be aligned to a multiple of the page size.
If the
len
parameter is not a multiple of the page size, it will be rounded up
to be so.
The entire range must be allocated.
After an mlock call, the indicated pages will cause neither a non-resident page nor address-translation fault until they are unlocked. They may still cause protection-violation faults or TLB-miss faults on architectures with software-managed TLBs. The physical pages remain in memory until all locked mappings for the pages are removed. Multiple processes may have the same physical pages locked via their own virtual address mappings. A single process may likewise have pages multiply-locked via different virtual mappings of the same pages or via nested mlock calls on the same address range. Unlocking is performed explicitly by munlock or implicitly by a call to munmap which deallocates the unmapped address range. Locked mappings are not inherited by the child process after a fork(2).
Since physical memory is a potentially scarce resource, processes are
limited in how much they can lock down.
A single process can
mlock
the minimum of
a system-wide ``wired pages'' limit and
the per-process
RLIMIT_MEMLOCK
resource limit.
)
will fail if:
EINVAL
]
EAGAIN
]
ENOMEM
]
EPERM
]
)
was called by non-root on an architecture where locked page accounting
is not implemented.
)
will fail if:
EINVAL
]
ENOMEM
]
)
and
munlock(
)
functions conform to
IEEE Std 1003.1b-1993 (``POSIX.1'') .
)
and
munlock(
)
functions first appeared in
4.4BSD.