Commit 0a1a9a00 authored by David Hildenbrand's avatar David Hildenbrand Committed by Linus Torvalds
Browse files

mm/memory_hotplug: simplify page offlining 



We make sure that we cannot have any memory holes right at the beginning
of offline_pages().  We no longer need walk_system_ram_range() and can
call test_pages_isolated() and __offline_isolated_pages() directly.

offlined_pages always corresponds to nr_pages, so we can simplify that.

[akpm@linux-foundation.org: patch conflict resolution]

Signed-off-by: default avatarDavid Hildenbrand <david@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Reviewed-by: default avatarOscar Salvador <osalvador@suse.de>
Acked-by: default avatarMichal Hocko <mhocko@suse.com>
Cc: Wei Yang <richard.weiyang@linux.alibaba.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Cc: Charan Teja Reddy <charante@codeaurora.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michel Lespinasse <walken@google.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Tony Luck <tony.luck@intel.com>
Link: https://lkml.kernel.org/r/20200819175957.28465-4-david@redhat.com


Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 4986fac1

mm/memory_hotplug.c

+10 −34
Original line number Diff line number Diff line
@@ -1384,28 +1384,6 @@ do_migrate_range(unsigned long start_pfn, unsigned long end_pfn) 
	return ret;

}



/* Mark all sections offline and remove all free pages from the buddy. */

static int

offline_isolated_pages_cb(unsigned long start, unsigned long nr_pages,

			void *data)

{

	unsigned long *offlined_pages = (unsigned long *)data;



	*offlined_pages += __offline_isolated_pages(start, start + nr_pages);

	return 0;

}



/*

 * Check all pages in range, recorded as memory resource, are isolated.

 */

static int

check_pages_isolated_cb(unsigned long start_pfn, unsigned long nr_pages,

			void *data)

{

	return test_pages_isolated(start_pfn, start_pfn + nr_pages,

				   MEMORY_OFFLINE);

}



static int __init cmdline_parse_movable_node(char *p)

{

	movable_node_enabled = true;
@@ -1492,7 +1470,7 @@ static int count_system_ram_pages_cb(unsigned long start_pfn, 
int __ref offline_pages(unsigned long start_pfn, unsigned long nr_pages)

{

	const unsigned long end_pfn = start_pfn + nr_pages;

	unsigned long pfn, system_ram_pages = 0, offlined_pages = 0;

	unsigned long pfn, system_ram_pages = 0;

	int ret, node, nr_isolate_pageblock;

	unsigned long flags;

	struct zone *zone;
@@ -1590,9 +1568,7 @@ int __ref offline_pages(unsigned long start_pfn, unsigned long nr_pages) 
			reason = "failure to dissolve huge pages";

			goto failed_removal_isolated;

		}

		/* check again */

		ret = walk_system_ram_range(start_pfn, end_pfn - start_pfn,

					    NULL, check_pages_isolated_cb);



		/*

		 * per-cpu pages are drained in start_isolate_page_range, but if

		 * there are still pages that are not free, make sure that we
@@ -1605,15 +1581,15 @@ int __ref offline_pages(unsigned long start_pfn, unsigned long nr_pages) 
		 * because has_unmovable_pages explicitly checks for

		 * PageBuddy on freed pages on other zones.

		 */

		ret = test_pages_isolated(start_pfn, end_pfn, MEMORY_OFFLINE);

		if (ret)

			drain_all_pages(zone);

	} while (ret);



	/* Ok, all of our target is isolated.

	   We cannot do rollback at this point. */

	walk_system_ram_range(start_pfn, end_pfn - start_pfn,

			      &offlined_pages, offline_isolated_pages_cb);

	pr_info("Offlined Pages %ld\n", offlined_pages);

	/* Mark all sections offline and remove free pages from the buddy. */

	__offline_isolated_pages(start_pfn, end_pfn);

	pr_info("Offlined Pages %ld\n", nr_pages);



	/*

	 * Onlining will reset pagetype flags and makes migrate type

	 * MOVABLE, so just need to decrease the number of isolated
@@ -1624,11 +1600,11 @@ int __ref offline_pages(unsigned long start_pfn, unsigned long nr_pages) 
	spin_unlock_irqrestore(&zone->lock, flags);



	/* removal success */

	adjust_managed_page_count(pfn_to_page(start_pfn), -offlined_pages);

	zone->present_pages -= offlined_pages;

	adjust_managed_page_count(pfn_to_page(start_pfn), -nr_pages);

	zone->present_pages -= nr_pages;



	pgdat_resize_lock(zone->zone_pgdat, &flags);

	zone->zone_pgdat->node_present_pages -= offlined_pages;

	zone->zone_pgdat->node_present_pages -= nr_pages;

	pgdat_resize_unlock(zone->zone_pgdat, &flags);



	init_per_zone_wmark_min();

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