mlock() and vm_max_wired

[Dmitry Sivachenko]

Hello!

I am using FreeBSD-10/stable and have a problem with mlock().
I have 256GB of memory and a program which does mmap+mlock on a number of data files.  It can process one file several times (so it does mmap() + mlock() on the same file more than once).
I set vm.max_wired=67108864 (67108864 * 4k = 256GB), so it is allowed to mlock() the whole RAM.

The total size of all files is about 180GB.

The program fails with mlock: Resource temporarily unavailable  error.

If I increase vm.max_wired even more, the program works fine and after it starts top(1) shows about 186GB of Wired memory.

Why does it fail with vm.max_wired=67108864?  Is it a bug or am I missing something?

Thanks.