Re: + memory-hotplug-exclude-isolated-page-from-pco-page-alloc.patch added to -mm tree

Re: + memory-hotplug-exclude-isolated-page-from-pco-page-alloc.patch added to -mm tree

[Shaohua Li]

On Tue, Jun 30, 2009 at 06:20:00AM +0800, Christoph Lameter wrote:
> On Mon, 29 Jun 2009, akpm@linux-foundation.org wrote:
> 
> > Pages marked as isolated should not be allocated again.  If such pages
> > reside in pcp list, they can be allocated too, so there is a ping-pong
> > memory offline frees some pages to pcp list and the pages get allocated
> > and then memory offline frees them again, this loop will happen again and
> > again.
> 
> Isolated pages are freed? Could they not be kept on a separate
> list with refcount elevated until the isolation procedure is complete?
Yes, they can be freed and add into pcp list. Moving them to a separate list
is feasible, but the approach is more intrusive to me. As I explained in the
patch, adding check in buffered_rmqueue() should hasn't impact for normal path.

Thanks,
Shaohua

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