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

David Rientjes
2011-10-20T05:20:02Z

On Mon, 17 Oct 2011, Mel Gorman wrote:

> (Resending as I am not seeing it in -next so maybe it got lost)
>
> mm: memory hotplug: Check if pages are correctly reserved on a per-section basis
>
> 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 those 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.
>
> [Check pages within sections properly: rientjes@google.com]
> [original patch by: nfont@linux.vnet.ibm.com]
> Signed-off-by: Mel Gorman <mgorman@suse.de>

Acked-by: David Rientjes <rientjes@google.com>