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Date: Fri, 16 Apr 2004 15:46:52 -0700
From: Andrew Morton <akpm@osdl.org>
To: Jamie Lokier <jamie@shareable.org>
Cc: linux-kernel@vger.kernel.org
Subject: Re: msync() needed before munmap() when writing to shared mapping?
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Jamie Lokier <jamie@shareable.org> wrote:
>
> I've followed the logic from do_munmap() and it looks good:
> unmap_vmas->zap_pte_range->page_remove_rmap->set_page_dirty.
> 
> Can someone confirm this is correct, please?

yup, zap_pte_range() transfers pte dirtiness into pagecache dirtiness when
tearing down the mapping, leaving the dirty page floating about in
pagecache for kupdate/kswapd/fsync to catch.  Longstanding behaviour.