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Date: Mon, 11 May 2015 22:47:19 -0700
From: "H. Peter Anvin" <hpa@zytor.com>
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To: Linus Torvalds <torvalds@linux-foundation.org>
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        Arnd Bergmann <arnd@arndb.de>
Subject: Re: VERIFY_READ/WRITE in uaccess.h?
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On 05/11/2015 02:42 PM, Linus Torvalds wrote:
> 
> That one - for the same reasons - also checked the actual accesses,
> not just that the range was in user mode. Exactly because it needed to
> pre-COW the pages (even if that was then obviously racy in threaded
> environments - in practice it worked, and we tried to support the
> fundamentally broken i386 hardware protection model for a long time).
> 

It worked in part because we never supported SMP on i386.

	-hpa