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From: hpa@zytor.com (H. Peter Anvin)
Subject: Re: msync() needed before munmap() when writing to shared mapping?
Date: Sat, 17 Apr 2004 20:23:21 +0000 (UTC)
Organization: Transmeta Corporation, Santa Clara CA
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Followup to:  <20040416220223.GA27084@mail.shareable.org>
By author:    Jamie Lokier <jamie@shareable.org>
In newsgroup: linux.dev.kernel
> 
> > munmap() and fsync() or msync() will flush it to disk; there is no
> > reason munmap() should unless perhaps the file was opened O_SYNC.
> 
> That was talking about flushing data all the way to disk.  The
> implication of hpa's response is that munmap() does propagate the
> dirty bits from the page table to the file.  That is the obvious
> behaviour, and what I've always assumed.
> 

Obvious behaviour, and required by POSIX.

	-hpa