Message-ID: <41408F61.503@yahoo.com.au>
Date: Fri, 10 Sep 2004 03:14:09 +1000
From: Nick Piggin <nickpiggin@yahoo.com.au>
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To: William Lee Irwin III <wli@holomorphy.com>
CC: Pavel Machek <pavel@ucw.cz>, Andrew Morton <akpm@osdl.org>,
       Andrey Savochkin <saw@saw.sw.com.sg>, linux-kernel@vger.kernel.org
Subject: Re: Q about pagecache data never written to disk
References: <20040905120147.A9202@castle.nmd.msu.ru> <20040905035233.6a6b5823.akpm@osdl.org> <20040905154336.B9202@castle.nmd.msu.ru> <20040905140040.58a5fcdc.akpm@osdl.org> <20040909123957.GB1065@elf.ucw.cz> <41405773.3090403@yahoo.com.au> <20040909133703.GA32038@atrey.karlin.mff.cuni.cz> <41405B51.20705@yahoo.com.au> <20040909172433.GA3106@holomorphy.com>
In-Reply-To: <20040909172433.GA3106@holomorphy.com>
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William Lee Irwin III wrote:
> On Thu, Sep 09, 2004 at 11:32:01PM +1000, Nick Piggin wrote:
> 
>>writeback isn't, but the pages will get marked dirty at unmap.
>>But I think I am wrong actually - I don't actually see why the
>>user would have to have the file open.
> 
> 
> Dirty memory "limits" have no force as applied to mmap() IO, which is
> not a pretty state of affairs with respect to various attempts the VM
> makes at mitigating data structure proliferation associated with dirty
> data.
> 

Yeah I know. data structure proliferation and just the simple fact
that it can't immediately be freed is a problem.

What is the alternative? Take a fault every time we write to a clean,
mmapped page?
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