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

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Message-ID: <20170616081142.GA3871@WeideMacBook-Pro.local>
Date:   Fri, 16 Jun 2017 16:11:42 +0800
From:   Wei Yang <richard.weiyang@...il.com>
To:     Michal Hocko <mhocko@...nel.org>
Cc:     Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
        Mel Gorman <mgorman@...e.de>, Vlastimil Babka <vbabka@...e.cz>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Jerome Glisse <jglisse@...hat.com>,
        Reza Arbab <arbab@...ux.vnet.ibm.com>,
        Yasuaki Ishimatsu <yasu.isimatu@...il.com>,
        qiuxishi@...wei.com, Kani Toshimitsu <toshi.kani@....com>,
        slaoub@...il.com, Joonsoo Kim <js1304@...il.com>,
        Andi Kleen <ak@...ux.intel.com>,
        David Rientjes <rientjes@...gle.com>,
        Daniel Kiper <daniel.kiper@...cle.com>,
        Igor Mammedov <imammedo@...hat.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Michal Hocko <mhocko@...e.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Heiko Carstens <heiko.carstens@...ibm.com>,
        Martin Schwidefsky <schwidefsky@...ibm.com>
Subject: Re: [PATCH 11/14] mm, memory_hotplug: do not associate hotadded
 memory to zones until online

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@...e.com>
>
[...]
+
>+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?

-- 
Wei Yang
Help you, Help me

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