Re: [RFC][PATCH] nameing reserved pages [0/3]

[Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>]

Arjan van de Ven wrote:

> On Wed, 2005-04-20 at 23:15 +0900, Kamezawa Hiroyuki wrote:
>  
>
> MCA's probably shouldn't set PG_reserved; I don't see why they should.
> They could just steal the page and "leak" it.
>  
Actually leaked pages cannot be hot-removed/replaced. So we have to 
trace which pages is removed by MCA.
I think Set PG_reserved and set page->private = Removed_by_MCA is a 
simple idea.

> > > /dev/memstate really looks like a bad idea to me as well... I rather
> > > have less than more /dev/*mem*
> > >
> > >
> > >      
> > For showing page usage and its "location", I've thought of other 
> > interface, sysfs, procfs...
> > But I have no idea.
> >    
>
> Why do you want this exported to userspace? There is absolutely no way
> you can get this exported race free without shutting the VM down, and
> without being race free this information has absolutely no meaning !!
>  
No meaning ? 
Before memory-hotremove, we can guessing whether memory is hot-removable 
or not.
As you say , this is not atomic and not fully responsible.

After failing memory-hotremove, detecting why hot-remove was failed is 
very important.
I think ,when memory hot-remove faild, memory area is isolated until it 
is pushed back by an operator.
We can get a real snapshot of specified memory area.

Regards,
-- Kame

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