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Date: Wed, 20 Nov 2013 13:00:11 -0800
From: "H. Peter Anvin" <hpa@zytor.com>
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To: Andi Kleen <andi@firstfloor.org>
CC: x86@kernel.org, linux-kernel@vger.kernel.org,
        Ingo Molnar <mingo@kernel.org>, Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH] Add a text_poke syscall
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On 11/20/2013 09:25 AM, Andi Kleen wrote:
> "H. Peter Anvin" <hpa@zytor.com> writes:
>>
>> We're talking user space here, which has different requirement (COW,
>> memory protection, ...) which means it is not really the same code.  You
>> can't take a page fault while patching the kernel.
> 
> The syscall pins the page, then it calls the kernel code.
> There are no page faults during patching.
> 

But you don't need to pin anything if you just do it in userspace.
Again, it is particularly poignant for large batched operations.

	-hpa