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Date: Thu, 09 May 2002 06:07:03 -0700 (PDT)
Message-Id: <20020509.060703.121443473.davem@redhat.com>
To: hugh@veritas.com
Cc: torvalds@transmeta.com, akpm@zip.com.au, cr@sap.com,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] double flush_page_to_ram
From: "David S. Miller" <davem@redhat.com>
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   From: Hugh Dickins <hugh@veritas.com>
   Date: Thu, 9 May 2002 14:18:49 +0100 (BST)

   On Thu, 9 May 2002, David S. Miller wrote:
   > Wrong, consider the case where we do early COW in do_no_page, you miss
   > a flush on the new-new page.
   
   Of course we do, and then we don't map it into user address space;
   if it ever gets mapped into user address space later, do_no_page
   does the flush_page_to_ram then.

You miss the fact that if we do an early COW and another process
recently WROTE into that page via a shared MMAP, we will potentially
copy old data into the COW page we use for the current process.

Your changes are wrong and will cause corruption.