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Date: Fri, 27 Sep 2002 19:44:08 +0200 (CEST)
From: Ingo Molnar <mingo@elte.hu>
Reply-To: Ingo Molnar <mingo@elte.hu>
To: Linus Torvalds <torvalds@transmeta.com>
Cc: Andrew Morton <akpm@zip.com.au>, Rusty Russell <rusty@rustcorp.com.au>,
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Subject: Re: [patch] 'virtual => physical page mapping cache', vcache-2.5.38-B8
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and i'm not quite sure how other users of get_user_pages() (direct-IO)
handle these kinds of COW races. A COW can invalidate a physical page
anytime, so the DMA might go to the fork()ed child process, creating very
unexpected results. We are protected against kswapd via the elevated page
count, but are not protected against COW.

	Ingo

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