Subject: Re: [PATCH v2] powerpc: Track backing pages allocated by vmemmap_populate()

From: Benjamin Herrenschmidt <[email-masked]>
Date: Tue, 13 Apr 2010 21:16:44 +1000

On Tue, 2010-04-13 at 16:02 +1000, Mark Nelson wrote:
> That's a good question, and one that I probably should have added to
> the
> commit message.
> But, following through, it looks like we end up calling into
> __remove_section() from mm/memory_hotplug.c and if
> CONFIG_SPARSEMEM_VMEMMAP is enabled we just return EBUSY as freeing
> memmap with vmemmap isn't implemented yet.
> 
> So for the moment, I'm not sure we have to worry about it.

We probably don't. IE. The vmemmap will remain for those struct pages,
which means they won't need to be allocated again if some memory is
plugged back there. If not, we just waste a bit of memory. Not a big
deal.

Cheers,
Ben.