Re: [PATCH 1 of 6] hotplug-memory: refactor online_pages to separatezone growth from page onlining

[Jeremy Fitzhardinge]

Yasunori Goto wrote:
> > +/* Mark a set of pages as online */
> > +unsigned long mark_pages_onlined(unsigned long pfn, unsigned long nr_pages)
> > +{
> > +	struct zone *zone = page_zone(pfn_to_page(pfn));
> > +	unsigned long onlined_pages = 0;
> > +	int need_zonelists_rebuild = 0;
> >  
> >  	/*
> >  	 * If this zone is not populated, then it is not in zonelist.
> > @@ -240,10 +246,38 @@
> >  	vm_total_pages = nr_free_pagecache_pages();
> >  	writeback_set_ratelimit();
> >  
> > -	if (onlined_pages)
> > +	if (onlined_pages) {
> > +		struct memory_notify arg;
> > +
> > +		arg.start_pfn = pfn;  /* ? */
> > +		arg.nr_pages = onlined_pages;
> > +		arg.status_change_nid = -1;  /* ? */
> >     
>
> status_change_nid is to prepare data structures which are allocated on
> each NUMA node.
>   

OK.  I didn't really understand the intent this logic in the 
GOING_ONLINE notifier path:

	arg.status_change_nid = -1;

	nid = page_to_nid(pfn_to_page(pfn));
	if (node_present_pages(nid) == 0)
		arg.status_change_nid = nid;

and how that should relate to the ONLINE notifier.

> When memory less node gets new memory, and it changes status
> to normal memory, then status_change_nid must be set.
>
> SLUB uses it now.
>   

Only for GOING_ONLINE. 

   J
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