Re: [linux-pm] [PATCH] hibernation should work ok with memory hotplug

[Dave Hansen <dave@linux.vnet.ibm.com>]

On Tue, 2008-11-04 at 16:35 +0100, Rafael J. Wysocki wrote:
> On Tuesday, 4 of November 2008, Dave Hansen wrote:
> > On Tue, 2008-11-04 at 09:54 +0100, Rafael J. Wysocki wrote:
> > > To handle this, I need to know two things:
> > > 1) what changes of the zones are possible due to memory hotplugging
> > > (i.e.    can they grow, shring, change boundaries etc.)
> > 
> > All of the above. 
> 
> OK
> 
> If I allocate a page frame corresponding to specific pfn, is it guaranteed to
> be associated with the same pfn in future?

Page allocation is different.  Since you hold a reference to a page, it
can not be removed until you release that reference.  That's why every
normal alloc_pages() user in the kernel doesn't have to worry about
memory hotplug.

> > Why walk zones instead of pgdats? 
> 
> This is a historical thing rather than anything else.  I think we could switch
> to pgdats, but that would require a code rewrite that's likely to introduce
> bugs, while our image-creating code is really well tested and doesn't change
> very often.

OK, fair enough.  I just wanted you to know that there are options other
than zones.

-- Dave