This patch moves some LRU list handling code out of the swap-code.
These can be used by memory-migration code.

Signed-off-by: Hirokazu Takahashi <taka@valinux.co.jp>
Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
---

 memhotplug-dave/include/linux/mm_inline.h |   68 ++++++++++++++++++++++++++++++
 memhotplug-dave/mm/vmscan.c               |   25 +----------
 2 files changed, 72 insertions(+), 21 deletions(-)

diff -puN include/linux/mm_inline.h~AA-PM-01-steal_page_from_lru include/linux/mm_inline.h
--- memhotplug/include/linux/mm_inline.h~AA-PM-01-steal_page_from_lru	2005-07-28 13:50:31.000000000 -0700
+++ memhotplug-dave/include/linux/mm_inline.h	2005-07-28 13:50:31.000000000 -0700
@@ -38,3 +38,71 @@ del_page_from_lru(struct zone *zone, str
 		zone->nr_inactive--;
 	}
 }
+
+static inline int
+isolate_lru_onepage(struct page *page, struct list_head *src,
+			struct list_head *dst)
+{
+	if (!TestClearPageLRU(page))
+		BUG();
+	list_del(&page->lru);
+	if (get_page_testone(page)) {
+		/*
+		 * It is being freed elsewhere
+		 */
+		__put_page(page);
+		SetPageLRU(page);
+		list_add(&page->lru, src);
+		return 0;
+	}
+	list_add(&page->lru, dst);
+	return 1;
+}
+
+
+static inline int
+__steal_page_from_lru(struct zone *zone, struct page *page,
+			struct list_head *dst)
+{
+	if (PageActive(page)) {
+		if (!isolate_lru_onepage(page, &zone->active_list, dst))
+			return 0;
+		zone->nr_active--;
+	} else {
+		if (!isolate_lru_onepage(page, &zone->inactive_list, dst))
+			return 0;
+		zone->nr_inactive--;
+	}
+	return 1;
+}
+
+static inline int
+steal_page_from_lru(struct zone *zone, struct page *page,
+			struct list_head *dst)
+{
+	int ret;
+	spin_lock_irq(&zone->lru_lock);
+	ret = __steal_page_from_lru(zone, page, dst);
+	spin_unlock_irq(&zone->lru_lock);
+	return ret;
+}
+
+static inline void
+__putback_page_to_lru(struct zone *zone, struct page *page)
+{
+	if (TestSetPageLRU(page))
+		BUG();
+	if (PageActive(page))
+		add_page_to_active_list(zone, page);
+	else
+		add_page_to_inactive_list(zone, page);
+}
+
+static inline void
+putback_page_to_lru(struct zone *zone, struct page *page)
+{
+	spin_lock_irq(&zone->lru_lock);
+	__putback_page_to_lru(zone, page);
+	spin_unlock_irq(&zone->lru_lock);
+}
+
diff -puN mm/vmscan.c~AA-PM-01-steal_page_from_lru mm/vmscan.c
--- memhotplug/mm/vmscan.c~AA-PM-01-steal_page_from_lru	2005-07-28 13:50:31.000000000 -0700
+++ memhotplug-dave/mm/vmscan.c	2005-07-28 13:50:31.000000000 -0700
@@ -582,22 +582,8 @@ static int isolate_lru_pages(int nr_to_s
 	while (scan++ < nr_to_scan && !list_empty(src)) {
 		page = lru_to_page(src);
 		prefetchw_prev_lru_page(page, src, flags);
-
-		if (!TestClearPageLRU(page))
-			BUG();
-		list_del(&page->lru);
-		if (get_page_testone(page)) {
-			/*
-			 * It is being freed elsewhere
-			 */
-			__put_page(page);
-			SetPageLRU(page);
-			list_add(&page->lru, src);
-			continue;
-		} else {
-			list_add(&page->lru, dst);
+		if (isolate_lru_onepage(page, src, dst))
 			nr_taken++;
-		}
 	}
 
 	*scanned = scan;
@@ -650,13 +636,10 @@ static void shrink_cache(struct zone *zo
 		 */
 		while (!list_empty(&page_list)) {
 			page = lru_to_page(&page_list);
-			if (TestSetPageLRU(page))
-				BUG();
 			list_del(&page->lru);
-			if (PageActive(page))
-				add_page_to_active_list(zone, page);
-			else
-				add_page_to_inactive_list(zone, page);
+ 			if (PageActive(page) && page_under_capture(page))
+ 				ClearPageActive(page);
+ 			__putback_page_to_lru(zone, page);
 			if (!pagevec_add(&pvec, page)) {
 				spin_unlock_irq(&zone->lru_lock);
 				__pagevec_release(&pvec);
_