Re: [patch 2/5] Reinstate ZERO_PAGE optimization in get_user_pages() and fix XIP

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To: Jeff Chua <jeff.chua.linux@...>
Cc: Greg KH <gregkh@...>, Linus Torvalds <torvalds@...>, <linux-kernel@...>, <stable@...>, Justin Forbes <jmforbes@...>, Zwane Mwaikambo <zwane@...>, Theodore Ts'o <tytso@...>, Randy Dunlap <rdunlap@...>, Dave Jones <davej@...>, Chuck Wolber <chuckw@...>, Chris Wedgwood <reviews@...>, Michael Krufky <mkrufky@...>, Chuck Ebbert <cebbert@...>, Domenico Andreoli <cavokz@...>, Willy Tarreau <w@...>, Rodrigo Rubira Branco <rbranco@...>, <akpm@...>, <alan@...>, Oleg Nesterov <oleg@...>, Nick Piggin <npiggin@...>, KAMEZAWA Hiroyuki <kamezawa.hiroyu@...>, Ingo Molnar <mingo@...>, Roland McGrath <roland@...>
Date: Monday, June 23, 2008 - 12:04 pm

On Mon, 23 Jun 2008, Jeff Chua wrote:

Long?!  That was very quick, thanks for reporting back.

But I'm afraid you've pushed me into taking another look at that
patch, and I see a problem with it.  To be honest, I've lost the
plot on this issue, and didn't really get what your problem is,
nor how Linus expected to be fixing it.

The problem is that "insane" VM_LOCKED test which he has removed.
I've remembered now what that's about: it's for make_pages_present.
We do want mlocking a readonly area to make its pages present, even
if they're not at this moment writable: we don't want the ZERO_PAGE
substitution in that case.

So I think Linus needs to factor that into the final patch,
whilst at the same time solving whatever is the vmware breakage.

Hugh
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Messages in current thread:
[patch 0/5] 2.6.25-stable review, Greg KH, (Sun Jun 22, 3:01 pm)
Re: [patch 0/5] 2.6.25-stable review, S.Çağlar, (Mon Jun 23, 7:19 am)
Re: [stable] [patch 0/5] 2.6.25-stable review, Greg KH, (Mon Jun 23, 3:30 pm)
Re: [patch 2/5] Reinstate ZERO_PAGE optimization in get_user..., Hugh Dickins, (Mon Jun 23, 12:04 pm)
[patch 4/5] x86: use BOOTMEM_EXCLUSIVE on 32-bit, Greg KH, (Sun Jun 22, 3:01 pm)
Re: [patch 4/5] x86: use BOOTMEM_EXCLUSIVE on 32-bit, Johannes Weiner, (Sun Jun 22, 4:22 pm)
Re: [patch 4/5] x86: use BOOTMEM_EXCLUSIVE on 32-bit, Linus Torvalds, (Sun Jun 22, 4:36 pm)
Re: [patch 4/5] x86: use BOOTMEM_EXCLUSIVE on 32-bit, Ingo Molnar, (Mon Jun 23, 4:09 am)
Re: [patch 4/5] x86: use BOOTMEM_EXCLUSIVE on 32-bit, Bernhard Walle, (Mon Jun 23, 6:33 am)
Re: [patch 4/5] x86: use BOOTMEM_EXCLUSIVE on 32-bit, Ingo Molnar, (Mon Jun 23, 6:53 am)
Re: [patch 4/5] x86: use BOOTMEM_EXCLUSIVE on 32-bit, Bernhard Walle, (Mon Jun 23, 9:21 am)
Re: [patch 4/5] x86: use BOOTMEM_EXCLUSIVE on 32-bit, Adrian Bunk, (Sun Jun 22, 4:36 pm)