Re: [PATCH] mm: memory hotplug: Check if pages are correctly reserved on a per-section basis

Greg KH
2011-10-10T23:24:22Z

On Mon, Oct 10, 2011 at 03:00:38PM -0700, Andrew Morton wrote:
> On Mon, 10 Oct 2011 08:11:19 +0100
> Mel Gorman <mgorman@suse.de> wrote:
>
> > It is expected that memory being brought online is PageReserved
> > similar to what happens when the page allocator is being brought up.
> > Memory is onlined in "memory blocks" which consist of one or more
> > sections. Unfortunately, the code that verifies PageReserved is
> > currently assuming that the memmap backing all these pages is virtually
> > contiguous which is only the case when CONFIG_SPARSEMEM_VMEMMAP is set.
> > As a result, memory hot-add is failing on !VMEMMAP configurations
> > with the message;
> >
> > kernel: section number XXX page number 256 not reserved, was it already online?
> >
> > This patch updates the PageReserved check to lookup struct page once
> > per section to guarantee the correct struct page is being checked.
> >
>
> Nathan's earlier version of this patch is already in linux-next, via
> Greg. We should drop the old version and get the new one merged
> instead.

Ok, care to send me what exactly needs to be reverted and what needs to
be added?

thanks,

greg k-h