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Date: Fri, 16 Jul 2004 16:45:45 +0200
From: Corinna Vinschen <corinna-cygwin AT cygwin DOT com>
To: cygwin AT cygwin DOT com
Subject: Re: mmap bug on Windows 9x
Message-ID: <20040716144545.GB31158@cygbert.vinschen.de>
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References: <E1BlMt7-0004hw-G0 AT a4 DOT complang DOT tuwien DOT ac DOT at>
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On Jul 16 09:12, Anton Ertl wrote:
> Anton Ertl wrote:
> > 
> > On Windows 9x/ME different calls to mmap sometimes produce the same
> > address (without that memory being unmapped in the meantime, at least
> > not by application code).
> 
> You find a condensed test program below.
> 
> On Windows ME with cygwin1.dll 1.5.10 it outputs:
> 
> try mmap($0, $40000, ..., MAP_ANON, ...); success, address=$833ca000
> try mmap($8340b000, $40000, ..., MAP_ANON, ...); success, address=$833ca000
> 
> Note that the result addresses are the same.

Thanks for the testcase!  Wow, I'm impressed.  Three serious bug reports
in two days which all had a simple testcase(tm) attached! 

*Sob*, I'm moved to tears.

Anyway, I found the cause of that problem.  For some reason (moon phase
or so) the mmap code didn't marked pages as used when running under 9x/Me.
This could only be observed under a specific condition of mmapping
anonymous private pages.

I've applied a fix to the repository.  Should be in the next developers
snapshot from http://cygwin.com/snapshots/


Thanks for the report,
Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Co-Project Leader          mailto:cygwin AT cygwin DOT com
Red Hat, Inc.

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