On 03/30/2013 12:17 AM, Sam Ravnborg wrote: >>>> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c >>>> index 97454b3..9b1b494 100644 >>>> --- a/mm/memory_hotplug.c >>>> +++ b/mm/memory_hotplug.c >>>> @@ -751,10 +751,6 @@ EXPORT_SYMBOL_GPL(restore_online_page_callback); >>>> >>>> void __online_page_set_limits(struct page *page) >>>> { >>>> - unsigned long pfn = page_to_pfn(page); >>>> - >>>> - if (pfn >= num_physpages) >>>> - num_physpages = pfn + 1; >>>> } >>>> EXPORT_SYMBOL_GPL(__online_page_set_limits); >>> >>> How can this be correct? >>> With this change __online_page_set_limits() is now a nop. >> Hi Sam, >> We will eventually remove the global variable num_physpages in the last patch. >> I kept the nop __online_page_set_limits() because I have a plan to use it to fix other >> bugs in memory hotplug, otherwise it may be killed too. > > The xen ballon driver uses __online_page_set_limits for memory > hotplug - so this will break this driver afaics. Hi Sam, I haven't gotten your point yet here. Function __online_page_set_limits() was only used to update the global variable num_physpages, and one of the goals of this patch set is to get rid of num_physpages. So I think it won't break Xen balloon driver. Please refer to the patch here, which eventually kills num_physpages. http://marc.info/?l=linux-mm&m=136431387813309&w=2 Regards! Gerry > > Sam > -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html