Re: + x86-implement-pte_special.patch added to -mm tree

Re: + x86-implement-pte_special.patch added to -mm tree

[Vegard Nossum]

On 6/3/08, akpm@linux-foundation.org <akpm@linux-foundation.org> wrote:
>
>  The patch titled
>      x86: implement pte_special
>  has been added to the -mm tree.  Its filename is
>      x86-implement-pte_special.patch

...

>  ------------------------------------------------------
>  Subject: x86: implement pte_special
>  From: Nick Piggin <npiggin@suse.de>
>
>  Implement the pte_special bit for x86.  This is required to support
>  lockless get_user_pages, because we need to know whether or not we can
>  refcount a particular page given only its pte (and no vma).

Wait... what the heck is a "special" page? Isn't that a terrible name
for _anything_? Or is there a tradition to the name? It sounds like it
should be named "novma" or "autonomous" or something instead.
Something that carries at least a little more information than
"special". Where can I find the documentation for this bit?

Has this been discussed on LKML? Is the name a result of consensus or whim?

Help! :-)


Vegard

-- 
"The animistic metaphor of the bug that maliciously sneaked in while
the programmer was not looking is intellectually dishonest as it
disguises that the error is the programmer's own creation."
	-- E. W. Dijkstra, EWD1036

Re: + x86-implement-pte_special.patch added to -mm tree

[Nick Piggin]

On Tue, Jun 03, 2008 at 05:53:22PM +0200, Vegard Nossum wrote:
> On 6/3/08, akpm@linux-foundation.org <akpm@linux-foundation.org> wrote:
> >
> >  The patch titled
> >      x86: implement pte_special
> >  has been added to the -mm tree.  Its filename is
> >      x86-implement-pte_special.patch
> 
> ...
> 
> >  ------------------------------------------------------
> >  Subject: x86: implement pte_special
> >  From: Nick Piggin <npiggin@suse.de>
> >
> >  Implement the pte_special bit for x86.  This is required to support
> >  lockless get_user_pages, because we need to know whether or not we can
> >  refcount a particular page given only its pte (and no vma).
> 
> Wait... what the heck is a "special" page? Isn't that a terrible name
> for _anything_? Or is there a tradition to the name? It sounds like it
> should be named "novma" or "autonomous" or something instead.
> Something that carries at least a little more information than
> "special". Where can I find the documentation for this bit?

It's the logical opposite of a "normal" page.

 
> Has this been discussed on LKML? Is the name a result of consensus or whim?

It has been posted many times.