linux-kernel - Calling free_pages on part of the memory returned by get_free

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Date:	Mon, 21 Apr 2008 16:12:14 -0500
From:	Timur Tabi <timur@...escale.com>
To:	lkml <linux-kernel@...r.kernel.org>
Subject: Calling free_pages on part of the memory returned by get_free_pages?

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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