linux-kernel - Re: PTE access rules & abstraction

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Date:	Thu, 25 Sep 2008 11:04:46 +1000
From:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
To:	Hugh Dickins <hugh@...itas.com>
Cc:	Jeremy Fitzhardinge <jeremy@...p.org>,
	Linux Memory Management List <linux-mm@...ck.org>,
	Linux Kernel list <linux-kernel@...r.kernel.org>,
	Nick Piggin <npiggin@...e.de>,
	Martin Schwidefsky <schwidefsky@...ibm.com>
Subject: Re: PTE access rules & abstraction

On Thu, 2008-09-25 at 00:55 +0100, Hugh Dickins wrote:
> 
> Whyever not the latter?  Jeremy seems to have gifted that to you,
> for precisely such a purpose.

Yeah. Not that I don't quite understand what the point of the
start/modify/commit thing the way it's currently used in mprotect since
we are doing the whole transaction for a single PTE change, ie how does
that help with hypervisors vs. a single ptep_modify_protection() for
example is beyond me :-)

When I think about transactions, I think about starting a transaction,
changing a -bunch- of PTEs, then commiting... Essentially I see the PTE
lock thing as being a transaction.

Cheers,
Ben.

> Hugh
> 
> p.s. I surely agree with you over the name ptep_get_and_clear_full():
> horrid, even more confusing than the tlb->fullmm from which it derives
> its name.  I expect I'd agree with you over a lot more too, but
> please, bugfixes first.

Sure.

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