linux-kernel - Re: Cached IO Synchronization Question

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Message-ID: <49DCC936.70509@pikewerks.com>
Date:	Wed, 08 Apr 2009 08:56:38 -0700
From:	Matt Klein <matt.klein@...ewerks.com>
To:	Peter Zijlstra <peterz@...radead.org>
CC:	linux-kernel@...r.kernel.org, Nick Piggin <nickpiggin@...oo.com.au>
Subject: Re: Cached IO Synchronization Question

> 
> Note how do_generic_file_read() checks PageUptodate() and does a
> lock_page_killable() in case its not.
> 
> 
> 

As far as I can tell there is nothing to prevent the page from becoming
out of date (or someone doing a full page cached write) after the
PageUptodate() check returns up to date.

So I have concluded that cached read/write interleaving is not
synchronized. This is the behavior found on Windows.
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