Re: [PATCH 11/14] mm, memory_hotplug: do not associate hotadded memory to zones until online

[Wei Yang]

On Fri, Jun 16, 2017 at 10:45:55AM +0200, Michal Hocko wrote:
>On Fri 16-06-17 16:11:42, Wei Yang wrote:
>> Well, I love this patch a lot. We don't need to put the hotadd memory in one
>> zone and move it to another. This looks great!
>> 
>> On Mon, May 15, 2017 at 10:58:24AM +0200, Michal Hocko wrote:
>> >From: Michal Hocko <mhocko@xxxxxxxx>
>> >
>> [...]
>> +
>> >+void move_pfn_range_to_zone(struct zone *zone,
>> >+		unsigned long start_pfn, unsigned long nr_pages)
>> >+{
>> >+	struct pglist_data *pgdat = zone->zone_pgdat;
>> >+	int nid = pgdat->node_id;
>> >+	unsigned long flags;
>> >+	unsigned long i;
>> >+
>> >+	if (zone_is_empty(zone))
>> >+		init_currently_empty_zone(zone, start_pfn, nr_pages);
>> >+
>> >+	clear_zone_contiguous(zone);
>> >+
>> >+	/* TODO Huh pgdat is irqsave while zone is not. It used to be like that before */
>> >+	pgdat_resize_lock(pgdat, &flags);
>> >+	zone_span_writelock(zone);
>> >+	resize_zone_range(zone, start_pfn, nr_pages);
>> >+	zone_span_writeunlock(zone);
>> >+	resize_pgdat_range(pgdat, start_pfn, nr_pages);
>> >+	pgdat_resize_unlock(pgdat, &flags);
>> >+
>> >+	/*
>> >+	 * TODO now we have a visible range of pages which are not associated
>> >+	 * with their zone properly. Not nice but set_pfnblock_flags_mask
>> >+	 * expects the zone spans the pfn range. All the pages in the range
>> >+	 * are reserved so nobody should be touching them so we should be safe
>> >+	 */
>> >+	memmap_init_zone(nr_pages, nid, zone_idx(zone), start_pfn, MEMMAP_HOTPLUG);
>> >+	for (i = 0; i < nr_pages; i++) {
>> >+		unsigned long pfn = start_pfn + i;
>> >+		set_page_links(pfn_to_page(pfn), zone_idx(zone), nid, pfn);
>> > 	}
>> 
>> memmap_init_zone()->__init_single_page()->set_page_links()
>> 
>> Do I miss something that you call set_page_links() explicitly here?
>
>I guess you are right. Not sure why I've done this explicitly. I've most
>probably just missed that. Could you post a patch that removes the for
>loop.
>

Sure, I will come up with two patches based on you auto-latest branch.

>Thanks!
>-- 
>Michal Hocko
>SUSE Labs

-- 
Wei Yang
Help you, Help me

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