linux-kernel - Re: [PATCH 1/2] Introduce copy_user_handle

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Date:	Mon, 7 Jul 2008 18:43:03 +0200
From:	Andi Kleen <andi@...stfloor.org>
To:	Vitaly Mayatskikh <v.mayatskih@...il.com>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andi Kleen <andi@...stfloor.org>, linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH 1/2] Introduce copy_user_handle_tail routine

On Mon, Jul 07, 2008 at 02:12:56PM +0200, Vitaly Mayatskikh wrote:
> Vitaly Mayatskikh <v.mayatskih@...il.com> writes:
> 
> >> one), by limiting the byte-for-byte one to be within a page, but that 
> >> would be a "future enhancement" thing.
> >
> > Btw, how much does it cost to CPU to do a fault? Can it be compared with
> > average time of find_vma()?
> 
> Remark: this is for preventing fault in memset, not byte-to-byte copy.

memset never faults.

The current code doesn't handle it and it never happened.

-Andi
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