From owner-freebsd-hackers@FreeBSD.ORG  Mon Feb  6 21:54:13 2006
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Date: Mon, 06 Feb 2006 22:54:11 +0100
From: Raaf <freebsd@luna.afraid.org>
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Subject: Freeing mmapped memory
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Hi, i am working on a usb driver that allocates some memory when
the device is opened using malloc.

Now i want user processes to be able to access this memory using
mmap and i want to free this memory when it is no longer needed.

The problem is that there seems to be no way of knowing for my
driver at what time the memory is no longer mapped in a process
address space so that i can safely free this memory.