Re: [PATCH 1 of 4] mm: add a ptep_modify_prot transactionabstraction

From: Ingo Molnar
Date: Mon Jun 16 2008 - 14:51:12 EST



* Hugh Dickins <hugh@xxxxxxxxxxx> wrote:

> On Mon, 16 Jun 2008, Linus Torvalds wrote:
> > On Mon, 16 Jun 2008, Jeremy Fitzhardinge wrote:
> > >
> > > ptep_modify_prot_start() returns the current pte value, and puts the
> > > pte entry into a state where either the hardware will not update the
> > > pte, or if it does, the updates will be preserved on commit.
> > >
> > > ptep_modify_prot_commit() writes back the updated pte, makes sure that
> > > any hardware updates made since ptep_modify_prot_start() are
> > > preserved.
> >
> > Ok, I'm fine with this now that it's renamed to be clearly about just
> > protection bits.
> >
> > So
> >
> > Acked-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
>
> And seems very reasonable (and exceptionally well described) to me too.
>
> Acked-by: Hugh Dickins <hugh@xxxxxxxxxxx>

thanks guys, i've added the Acked-by's and added a new -tip topic for
this.

The dependencies are a bit tricky and the changes contain mm/ and
include/asm-generic/ bits so lets try a new Git trick here to keep it
all tidy and disciplined for v2.6.27 merging.

So i've created a new tip/mm/xen topic branch (the 85th -tip topic
branch ;-), which is COW-ed off the current tip/x86/xen topic branch [on
which branch these changes have some dependencies], and added these 4
changes to that. The tip/x86/xen (append-only-) topic will continue to
advance as usual, and we likely wont have dependencies on the stuff in
tip/mm/xen. (if there will be such dependencies we can handle that too)

In v2.6.27 we can then offer up the two branches separately for upstream
merge, and tip/x86/xen will still only have x86 and xen changes, not any
mm changes. (Obviously tip/mm/xen will be offered after tip/x86/xen has
gone upstream - so that it will only contain these 4 patches ontop of
already-upstream changes)

it will all be auto-merged into linux-next so there this internal
structure is not visible, all the changes are available for wide testing
of course.

i've added these mm/ changes to auto-core-next (not auto-x86-next), if
that is fine by Andrew.

Ingo
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