linux-kernel - Re: [PATCH 3/3] mm: move mirrored memory specific code outside of memmap_init

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Date:   Tue, 24 Jul 2018 18:18:00 -0700
From:   Andrew Morton <akpm@...ux-foundation.org>
To:     Pavel Tatashin <pasha.tatashin@...cle.com>
Cc:     steven.sistare@...cle.com, daniel.m.jordan@...cle.com,
        linux-kernel@...r.kernel.org, kirill.shutemov@...ux.intel.com,
        mhocko@...e.com, linux-mm@...ck.org, dan.j.williams@...el.com,
        jack@...e.cz, jglisse@...hat.com, jrdr.linux@...il.com,
        bhe@...hat.com, gregkh@...uxfoundation.org, vbabka@...e.cz,
        richard.weiyang@...il.com, dave.hansen@...el.com,
        rientjes@...gle.com, mingo@...nel.org,
        osalvador@...hadventures.net, abdhalee@...ux.vnet.ibm.com,
        mpe@...erman.id.au
Subject: Re: [PATCH 3/3] mm: move mirrored memory specific code outside of
 memmap_init_zone

On Tue, 24 Jul 2018 19:55:20 -0400 Pavel Tatashin <pasha.tatashin@...cle.com> wrote:

> memmap_init_zone, is getting complex, because it is called from different
> contexts: hotplug, and during boot, and also because it must handle some
> architecture quirks. One of them is mirroed memory.
> 
> Move the code that decides whether to skip mirrored memory outside of
> memmap_init_zone, into a separate function.

Conflicts a bit with the page_alloc.c hunk from
http://ozlabs.org/~akpm/mmots/broken-out/mm-page_alloc-remain-memblock_next_valid_pfn-on-arm-arm64.patch.  Please check my fixup:

void __meminit memmap_init_zone(unsigned long size, int nid, unsigned long zone,
		unsigned long start_pfn, enum memmap_context context,
		struct vmem_altmap *altmap)
{
	unsigned long pfn, end_pfn = start_pfn + size;
	struct page *page;

	if (highest_memmap_pfn < end_pfn - 1)
		highest_memmap_pfn = end_pfn - 1;

	/*
	 * Honor reservation requested by the driver for this ZONE_DEVICE
	 * memory
	 */
	if (altmap && start_pfn == altmap->base_pfn)
		start_pfn += altmap->reserve;

	for (pfn = start_pfn; pfn < end_pfn; pfn++) {
		/*
		 * There can be holes in boot-time mem_map[]s handed to this
		 * function.  They do not exist on hotplugged memory.
		 */
		if (context == MEMMAP_EARLY) {
			if (!early_pfn_valid(pfn)) {
				pfn = next_valid_pfn(pfn) - 1;
				continue;
			}
			if (!early_pfn_in_nid(pfn, nid))
				continue;
			if (overlap_memmap_init(zone, &pfn))
				continue;
			if (defer_init(nid, pfn, end_pfn))
				break;
		}

		page = pfn_to_page(pfn);
		__init_single_page(page, pfn, zone, nid);
		if (context == MEMMAP_HOTPLUG)
			SetPageReserved(page);

		/*
		 * Mark the block movable so that blocks are reserved for
		 * movable at startup. This will force kernel allocations
		 * to reserve their blocks rather than leaking throughout
		 * the address space during boot when many long-lived
		 * kernel allocations are made.
		 *
		 * bitmap is created for zone's valid pfn range. but memmap
		 * can be created for invalid pages (for alignment)
		 * check here not to call set_pageblock_migratetype() against
		 * pfn out of zone.
		 */
		if (!(pfn & (pageblock_nr_pages - 1))) {
			set_pageblock_migratetype(page, MIGRATE_MOVABLE);
			cond_resched();
		}
	}
}