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Subject: Re: [aarcange@redhat.com: [PATCH] fork vs gup(-fast) fix]
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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Date: Sat, 14 Mar 2009 16:07:21 +1100
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To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>, Ingo Molnar <mingo@elte.hu>, Nick Piggin <npiggin@novell.com>, Hugh Dickins <hugh@veritas.com>, KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>, KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>, linux-mm@kvack.org
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On Wed, 2009-03-11 at 13:33 -0700, Linus Torvalds wrote:
>  - Just make the rule be that people who use get_user_pages() always 
>    have to have the read-lock on mmap_sem until they've used the
> pages.
> 

That's not going to work with IB and friends who gup() whole bunches of
user memory forever...

Ben.


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