Calling free_pages on part of the memory returned by get_free_pages?

From: Timur Tabi
Date: Mon Apr 21 2008 - 17:12:30 EST


According to LDD3, if I call get_free_pages() to allocate X bytes, I have to
free all of those pages with free_pages(). The VM internals are a little bit
over my head, but I looked at the code and I didn't see why that is a requirement.

For example, let's say I want to allocated 6MB of physically-contiguous memory.
If I call x = get_free_pages(11) to get 8MB. What happens if I then do
"free_pages(x + 6 * 1024 * 1024, 9)"?

I remember doing this on the 2.4 kernel, and it never gave me any problems.

--
Timur Tabi
Linux kernel developer at Freescale
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