Re: [PATCH v3 04/13] mm, compaction: move pageblock checks up from isolate_migratepages_range()

[Vlastimil Babka]

On 06/24/2014 06:52 AM, Naoya Horiguchi wrote:
> > -	low_pfn = isolate_migratepages_range(zone, cc, low_pfn, end_pfn, false);
> > -	if (!low_pfn || cc->contended)
> > -		return ISOLATE_ABORT;
> > +		/* Do not scan within a memory hole */
> > +		if (!pfn_valid(low_pfn))
> > +			continue;
> > +
> > +		page = pfn_to_page(low_pfn);
>
> Can we move (page_zone != zone) check here as isolate_freepages() does?

Duplicate perhaps, not sure about move. Does CMA make sure that all 
pages are in the same zone? Common sense tells me it would be useless 
otherwise, but I haven't checked if we can rely on it.

> Thanks,
> Naoya Horiguchi

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