Reclaiming freed memory back from running process

1. Process have allocated a big chunk of memory
2. Process freed that memory (and it's still running)
3. Freed memory still available to the process for future re-use. So,
we don't see any memory usage reduction for that process - OK.
The question is: If system start getting out of memory will kernel
reclaim free memory that available for process use? Or kernel will take
it back only after process exits?

Thank you,