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Subject: Re: Having problem with mmap system call!!!
From: Alan Cox <alan@lxorguk.ukuu.org.uk>
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Date: Thu, 16 Sep 2004 21:01:16 +0100
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On Iau, 2004-09-16 at 19:13, Richard B. Johnson wrote:

> 	for (i = 0; i < v->page_count; i++) {
> 		unsigned long page = virt_to_phys((void *)v->desc[i]);
> 		if (remap_page_range(start, page, PAGE_SIZE, PAGE_READONLY)) {
> 			err = -EAGAIN;
> 			goto out;
> 		}
> 		start += PAGE_SIZE;

Actually thats a nice example of how easy it is to implement mmap
properly.


> you usually say... Anyway are you aware that ...
> 
> 	unsigned long size  = vma->vm_end - vma->vm_start;
> 
> ... ends up being 32 bytes longer than the length the user-mode
> code put into mmap()?

Its page aligned, that is what mmap() says happens.