mm: factor out memory isolate functions

mm/page_alloc.c has some memory isolation functions but they are used only
when we enable CONFIG_{CMA|MEMORY_HOTPLUG|MEMORY_FAILURE}.  So let's make
it configurable by new CONFIG_MEMORY_ISOLATION so that it can reduce
binary size and we can check it simple by CONFIG_MEMORY_ISOLATION, not if
defined CONFIG_{CMA|MEMORY_HOTPLUG|MEMORY_FAILURE}.

Signed-off-by: Minchan Kim <minchan@kernel.org>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 71 insertions, 0 deletions

diff --git a/mm/page_isolation.c b/mm/page_isolation.c
index c9f04774f2b..fb482cf438d 100644
--- a/mm/page_isolation.c
+++ b/mm/page_isolation.c
@@ -5,8 +5,79 @@
 #include <linux/mm.h>
 #include <linux/page-isolation.h>
 #include <linux/pageblock-flags.h>
+#include <linux/memory.h>
 #include "internal.h"
 
+int set_migratetype_isolate(struct page *page)
+{
+	struct zone *zone;
+	unsigned long flags, pfn;
+	struct memory_isolate_notify arg;
+	int notifier_ret;
+	int ret = -EBUSY;
+
+	zone = page_zone(page);
+
+	spin_lock_irqsave(&zone->lock, flags);
+
+	pfn = page_to_pfn(page);
+	arg.start_pfn = pfn;
+	arg.nr_pages = pageblock_nr_pages;
+	arg.pages_found = 0;
+
+	/*
+	 * It may be possible to isolate a pageblock even if the
+	 * migratetype is not MIGRATE_MOVABLE. The memory isolation
+	 * notifier chain is used by balloon drivers to return the
+	 * number of pages in a range that are held by the balloon
+	 * driver to shrink memory. If all the pages are accounted for
+	 * by balloons, are free, or on the LRU, isolation can continue.
+	 * Later, for example, when memory hotplug notifier runs, these
+	 * pages reported as "can be isolated" should be isolated(freed)
+	 * by the balloon driver through the memory notifier chain.
+	 */
+	notifier_ret = memory_isolate_notify(MEM_ISOLATE_COUNT, &arg);
+	notifier_ret = notifier_to_errno(notifier_ret);
+	if (notifier_ret)
+		goto out;
+	/*
+	 * FIXME: Now, memory hotplug doesn't call shrink_slab() by itself.
+	 * We just check MOVABLE pages.
+	 */
+	if (!has_unmovable_pages(zone, page, arg.pages_found))
+		ret = 0;
+
+	/*
+	 * immobile means "not-on-lru" paes. If immobile is larger than
+	 * removable-by-driver pages reported by notifier, we'll fail.
+	 */
+
+out:
+	if (!ret) {
+		set_pageblock_migratetype(page, MIGRATE_ISOLATE);
+		move_freepages_block(zone, page, MIGRATE_ISOLATE);
+	}
+
+	spin_unlock_irqrestore(&zone->lock, flags);
+	if (!ret)
+		drain_all_pages();
+	return ret;
+}
+
+void unset_migratetype_isolate(struct page *page, unsigned migratetype)
+{
+	struct zone *zone;
+	unsigned long flags;
+	zone = page_zone(page);
+	spin_lock_irqsave(&zone->lock, flags);
+	if (get_pageblock_migratetype(page) != MIGRATE_ISOLATE)
+		goto out;
+	set_pageblock_migratetype(page, migratetype);
+	move_freepages_block(zone, page, migratetype);
+out:
+	spin_unlock_irqrestore(&zone->lock, flags);
+}
+
 static inline struct page *
 __first_valid_page(unsigned long pfn, unsigned long nr_pages)
 {