linux-kernel - Re: Forbid deletion of memory mappings

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Message-ID: <Pine.LNX.4.64.0708302354240.2460@twin.jikos.cz>
Date:	Thu, 30 Aug 2007 23:55:37 +0200 (CEST)
From:	Jiri Kosina <jikos@...os.cz>
To:	Clemens Kolbitsch <clemens.kol@....at>
cc:	linux-kernel@...r.kernel.org
Subject: Re: Forbid deletion of memory mappings

On Thu, 30 Aug 2007, Clemens Kolbitsch wrote:

> the thing is that they are not. the kernel chooses to REPLACE my 
> mapping.
> consider the user-space code:
> mmap(0xaaaa0000, 0x3000, MAP_FIXED, ...);
> mmap(0xaaaa1000, 0x4000, MAP_FIXED, ...);
> here, the second call to mmap will shorten the first mapping to 0x1000 bytes 
> and create one big vma with size 0x5000 bytes.

Which is exactly in compliance with what POSIX says about MAP_FIXED mmaps 
- see http://opengroup.org/onlinepubs/007908799/xsh/mmap.html

-- 
Jiri Kosina
-
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