munlock() - unlock a segment of the process virtual address space
int munlock( const void * addr, size_t len) ;
The munlock() system call allows the calling process to unlock a
segment of the process virtual address space that may have been
previously locked with mlock() or mlockall(). Upon successful
completion of the munlock(), pages within the specified segment are
subject to routine paging and/or 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
Pages are unlocked at page boundaries that encompass the range from
addr to addr + len. If any address within the range is not a valid
part of the process virtual address space, an error is returned and no
unlocks are performed. However, no error is reported for valid pages
within the range that are not already locked, since their state at the
completion of the munlock() call is as desired.
Regardless of how many times a process locks a page, a single
munlock() or munlockall() will unlock it. An munlock() of a page
within a range specified in an mlock() call results in only the range
specified in the munlock() 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.
The effective user ID of the calling process must be a superuser or
the user must be a member of a group that has the MLOCK privilege (see
getprivgrp(2) and setprivgrp(1M)).
Although plock() and the mlock() family of functions may be used
together in an application, each may affect the other in unexpected
ways. This practice is not recommended.
munlock() returns the following values:
0 Successful completion.
-1 Failure. The requested operation is not performed. errno
is set to indicate the error.
Hewlett-Packard Company - 1 - HP-UX Release 11i: November 2000
If munlock() fails, errno is set to one of the following values:
[ENOMEM] One or more addresses in the specified range is
not valid within the process address space.
[EINVAL] The len parameter was zero.
[EPERM] The effective user ID of the calling process is
not a superuser and the user does not belong to a
group that has the MLOCK privilege.
The following call to munlock() unlocks the first 10 pages of the
calling process address space:
setprivgrp(1M), getprivgrp(2), mlock(2), mlockall(2), munlockall(2),
munlock(): POSIX Realtime Extensions, IEEE Std 1003.1b
Hewlett-Packard Company - 2 - HP-UX Release 11i: November 2000