Merge commit 'v2.6.28-rc2' into core/locking

Conflicts:
	arch/um/include/asm/system.h

1 files changed, 760 insertions, 266 deletions

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 1ff1a58e7c1..3b5860294bb 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -39,6 +39,7 @@
 #include <linux/freezer.h>
 #include <linux/memcontrol.h>
 #include <linux/delayacct.h>
+#include <linux/sysctl.h>
 
 #include <asm/tlbflush.h>
 #include <asm/div64.h>
@@ -78,7 +79,7 @@ struct scan_control {
 	unsigned long (*isolate_pages)(unsigned long nr, struct list_head *dst,
 			unsigned long *scanned, int order, int mode,
 			struct zone *z, struct mem_cgroup *mem_cont,
-			int active);
+			int active, int file);
 };
 
 #define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru))
@@ -470,6 +471,85 @@ int remove_mapping(struct address_space *mapping, struct page *page)
 	return 0;
 }
 
+/**
+ * putback_lru_page - put previously isolated page onto appropriate LRU list
+ * @page: page to be put back to appropriate lru list
+ *
+ * Add previously isolated @page to appropriate LRU list.
+ * Page may still be unevictable for other reasons.
+ *
+ * lru_lock must not be held, interrupts must be enabled.
+ */
+#ifdef CONFIG_UNEVICTABLE_LRU
+void putback_lru_page(struct page *page)
+{
+	int lru;
+	int active = !!TestClearPageActive(page);
+	int was_unevictable = PageUnevictable(page);
+
+	VM_BUG_ON(PageLRU(page));
+
+redo:
+	ClearPageUnevictable(page);
+
+	if (page_evictable(page, NULL)) {
+		/*
+		 * For evictable pages, we can use the cache.
+		 * In event of a race, worst case is we end up with an
+		 * unevictable page on [in]active list.
+		 * We know how to handle that.
+		 */
+		lru = active + page_is_file_cache(page);
+		lru_cache_add_lru(page, lru);
+	} else {
+		/*
+		 * Put unevictable pages directly on zone's unevictable
+		 * list.
+		 */
+		lru = LRU_UNEVICTABLE;
+		add_page_to_unevictable_list(page);
+	}
+	mem_cgroup_move_lists(page, lru);
+
+	/*
+	 * page's status can change while we move it among lru. If an evictable
+	 * page is on unevictable list, it never be freed. To avoid that,
+	 * check after we added it to the list, again.
+	 */
+	if (lru == LRU_UNEVICTABLE && page_evictable(page, NULL)) {
+		if (!isolate_lru_page(page)) {
+			put_page(page);
+			goto redo;
+		}
+		/* This means someone else dropped this page from LRU
+		 * So, it will be freed or putback to LRU again. There is
+		 * nothing to do here.
+		 */
+	}
+
+	if (was_unevictable && lru != LRU_UNEVICTABLE)
+		count_vm_event(UNEVICTABLE_PGRESCUED);
+	else if (!was_unevictable && lru == LRU_UNEVICTABLE)
+		count_vm_event(UNEVICTABLE_PGCULLED);
+
+	put_page(page);		/* drop ref from isolate */
+}
+
+#else /* CONFIG_UNEVICTABLE_LRU */
+
+void putback_lru_page(struct page *page)
+{
+	int lru;
+	VM_BUG_ON(PageLRU(page));
+
+	lru = !!TestClearPageActive(page) + page_is_file_cache(page);
+	lru_cache_add_lru(page, lru);
+	mem_cgroup_move_lists(page, lru);
+	put_page(page);
+}
+#endif /* CONFIG_UNEVICTABLE_LRU */
+
+
 /*
  * shrink_page_list() returns the number of reclaimed pages
  */
@@ -503,6 +583,9 @@ static unsigned long shrink_page_list(struct list_head *page_list,
 
 		sc->nr_scanned++;
 
+		if (unlikely(!page_evictable(page, NULL)))
+			goto cull_mlocked;
+
 		if (!sc->may_swap && page_mapped(page))
 			goto keep_locked;
 
@@ -539,9 +622,19 @@ static unsigned long shrink_page_list(struct list_head *page_list,
 		 * Anonymous process memory has backing store?
 		 * Try to allocate it some swap space here.
 		 */
-		if (PageAnon(page) && !PageSwapCache(page))
+		if (PageAnon(page) && !PageSwapCache(page)) {
+			switch (try_to_munlock(page)) {
+			case SWAP_FAIL:		/* shouldn't happen */
+			case SWAP_AGAIN:
+				goto keep_locked;
+			case SWAP_MLOCK:
+				goto cull_mlocked;
+			case SWAP_SUCCESS:
+				; /* fall thru'; add to swap cache */
+			}
 			if (!add_to_swap(page, GFP_ATOMIC))
 				goto activate_locked;
+		}
 #endif /* CONFIG_SWAP */
 
 		mapping = page_mapping(page);
@@ -556,6 +649,8 @@ static unsigned long shrink_page_list(struct list_head *page_list,
 				goto activate_locked;
 			case SWAP_AGAIN:
 				goto keep_locked;
+			case SWAP_MLOCK:
+				goto cull_mlocked;
 			case SWAP_SUCCESS:
 				; /* try to free the page below */
 			}
@@ -602,7 +697,7 @@ static unsigned long shrink_page_list(struct list_head *page_list,
 		 * possible for a page to have PageDirty set, but it is actually
 		 * clean (all its buffers are clean).  This happens if the
 		 * buffers were written out directly, with submit_bh(). ext3
-		 * will do this, as well as the blockdev mapping. 
+		 * will do this, as well as the blockdev mapping.
 		 * try_to_release_page() will discover that cleanness and will
 		 * drop the buffers and mark the page clean - it can be freed.
 		 *
@@ -637,7 +732,14 @@ static unsigned long shrink_page_list(struct list_head *page_list,
 		if (!mapping || !__remove_mapping(mapping, page))
 			goto keep_locked;
 
-		unlock_page(page);
+		/*
+		 * At this point, we have no other references and there is
+		 * no way to pick any more up (removed from LRU, removed
+		 * from pagecache). Can use non-atomic bitops now (and
+		 * we obviously don't have to worry about waking up a process
+		 * waiting on the page lock, because there are no references.
+		 */
+		__clear_page_locked(page);
 free_it:
 		nr_reclaimed++;
 		if (!pagevec_add(&freed_pvec, page)) {
@@ -646,14 +748,23 @@ free_it:
 		}
 		continue;
 
+cull_mlocked:
+		unlock_page(page);
+		putback_lru_page(page);
+		continue;
+
 activate_locked:
+		/* Not a candidate for swapping, so reclaim swap space. */
+		if (PageSwapCache(page) && vm_swap_full())
+			remove_exclusive_swap_page_ref(page);
+		VM_BUG_ON(PageActive(page));
 		SetPageActive(page);
 		pgactivate++;
 keep_locked:
 		unlock_page(page);
 keep:
 		list_add(&page->lru, &ret_pages);
-		VM_BUG_ON(PageLRU(page));
+		VM_BUG_ON(PageLRU(page) || PageUnevictable(page));
 	}
 	list_splice(&ret_pages, page_list);
 	if (pagevec_count(&freed_pvec))
@@ -677,7 +788,7 @@ keep:
  *
  * returns 0 on success, -ve errno on failure.
  */
-int __isolate_lru_page(struct page *page, int mode)
+int __isolate_lru_page(struct page *page, int mode, int file)
 {
 	int ret = -EINVAL;
 
@@ -693,6 +804,17 @@ int __isolate_lru_page(struct page *page, int mode)
 	if (mode != ISOLATE_BOTH && (!PageActive(page) != !mode))
 		return ret;
 
+	if (mode != ISOLATE_BOTH && (!page_is_file_cache(page) != !file))
+		return ret;
+
+	/*
+	 * When this function is being called for lumpy reclaim, we
+	 * initially look into all LRU pages, active, inactive and
+	 * unevictable; only give shrink_page_list evictable pages.
+	 */
+	if (PageUnevictable(page))
+		return ret;
+
 	ret = -EBUSY;
 	if (likely(get_page_unless_zero(page))) {
 		/*
@@ -723,12 +845,13 @@ int __isolate_lru_page(struct page *page, int mode)
  * @scanned:	The number of pages that were scanned.
  * @order:	The caller's attempted allocation order
  * @mode:	One of the LRU isolation modes
+ * @file:	True [1] if isolating file [!anon] pages
  *
  * returns how many pages were moved onto *@dst.
  */
 static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
 		struct list_head *src, struct list_head *dst,
-		unsigned long *scanned, int order, int mode)
+		unsigned long *scanned, int order, int mode, int file)
 {
 	unsigned long nr_taken = 0;
 	unsigned long scan;
@@ -745,7 +868,7 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
 
 		VM_BUG_ON(!PageLRU(page));
 
-		switch (__isolate_lru_page(page, mode)) {
+		switch (__isolate_lru_page(page, mode, file)) {
 		case 0:
 			list_move(&page->lru, dst);
 			nr_taken++;
@@ -788,10 +911,11 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
 				break;
 
 			cursor_page = pfn_to_page(pfn);
+
 			/* Check that we have not crossed a zone boundary. */
 			if (unlikely(page_zone_id(cursor_page) != zone_id))
 				continue;
-			switch (__isolate_lru_page(cursor_page, mode)) {
+			switch (__isolate_lru_page(cursor_page, mode, file)) {
 			case 0:
 				list_move(&cursor_page->lru, dst);
 				nr_taken++;
@@ -802,7 +926,7 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
 				/* else it is being freed elsewhere */
 				list_move(&cursor_page->lru, src);
 			default:
-				break;
+				break;	/* ! on LRU or wrong list */
 			}
 		}
 	}
@@ -816,40 +940,93 @@ static unsigned long isolate_pages_global(unsigned long nr,
 					unsigned long *scanned, int order,
 					int mode, struct zone *z,
 					struct mem_cgroup *mem_cont,
-					int active)
+					int active, int file)
 {
+	int lru = LRU_BASE;
 	if (active)
-		return isolate_lru_pages(nr, &z->active_list, dst,
-						scanned, order, mode);
-	else
-		return isolate_lru_pages(nr, &z->inactive_list, dst,
-						scanned, order, mode);
+		lru += LRU_ACTIVE;
+	if (file)
+		lru += LRU_FILE;
+	return isolate_lru_pages(nr, &z->lru[lru].list, dst, scanned, order,
+								mode, !!file);
 }
 
 /*
  * clear_active_flags() is a helper for shrink_active_list(), clearing
  * any active bits from the pages in the list.
  */
-static unsigned long clear_active_flags(struct list_head *page_list)
+static unsigned long clear_active_flags(struct list_head *page_list,
+					unsigned int *count)
 {
 	int nr_active = 0;
+	int lru;
 	struct page *page;
 
-	list_for_each_entry(page, page_list, lru)
+	list_for_each_entry(page, page_list, lru) {
+		lru = page_is_file_cache(page);
 		if (PageActive(page)) {
+			lru += LRU_ACTIVE;
 			ClearPageActive(page);
 			nr_active++;
 		}
+		count[lru]++;
+	}
 
 	return nr_active;
 }
 
+/**
+ * isolate_lru_page - tries to isolate a page from its LRU list
+ * @page: page to isolate from its LRU list
+ *
+ * Isolates a @page from an LRU list, clears PageLRU and adjusts the
+ * vmstat statistic corresponding to whatever LRU list the page was on.
+ *
+ * Returns 0 if the page was removed from an LRU list.
+ * Returns -EBUSY if the page was not on an LRU list.
+ *
+ * The returned page will have PageLRU() cleared.  If it was found on
+ * the active list, it will have PageActive set.  If it was found on
+ * the unevictable list, it will have the PageUnevictable bit set. That flag
+ * may need to be cleared by the caller before letting the page go.
+ *
+ * The vmstat statistic corresponding to the list on which the page was
+ * found will be decremented.
+ *
+ * Restrictions:
+ * (1) Must be called with an elevated refcount on the page. This is a
+ *     fundamentnal difference from isolate_lru_pages (which is called
+ *     without a stable reference).
+ * (2) the lru_lock must not be held.
+ * (3) interrupts must be enabled.
+ */
+int isolate_lru_page(struct page *page)
+{
+	int ret = -EBUSY;
+
+	if (PageLRU(page)) {
+		struct zone *zone = page_zone(page);
+
+		spin_lock_irq(&zone->lru_lock);
+		if (PageLRU(page) && get_page_unless_zero(page)) {
+			int lru = page_lru(page);
+			ret = 0;
+			ClearPageLRU(page);
+
+			del_page_from_lru_list(zone, page, lru);
+		}
+		spin_unlock_irq(&zone->lru_lock);
+	}
+	return ret;
+}
+
 /*
  * shrink_inactive_list() is a helper for shrink_zone().  It returns the number
  * of reclaimed pages
  */
 static unsigned long shrink_inactive_list(unsigned long max_scan,
-				struct zone *zone, struct scan_control *sc)
+			struct zone *zone, struct scan_control *sc,
+			int priority, int file)
 {
 	LIST_HEAD(page_list);
 	struct pagevec pvec;
@@ -866,20 +1043,43 @@ static unsigned long shrink_inactive_list(unsigned long max_scan,
 		unsigned long nr_scan;
 		unsigned long nr_freed;
 		unsigned long nr_active;
+		unsigned int count[NR_LRU_LISTS] = { 0, };
+		int mode = ISOLATE_INACTIVE;
+
+		/*
+		 * If we need a large contiguous chunk of memory, or have
+		 * trouble getting a small set of contiguous pages, we
+		 * will reclaim both active and inactive pages.
+		 *
+		 * We use the same threshold as pageout congestion_wait below.
+		 */
+		if (sc->order > PAGE_ALLOC_COSTLY_ORDER)
+			mode = ISOLATE_BOTH;
+		else if (sc->order && priority < DEF_PRIORITY - 2)
+			mode = ISOLATE_BOTH;
 
 		nr_taken = sc->isolate_pages(sc->swap_cluster_max,
-			     &page_list, &nr_scan, sc->order,
-			     (sc->order > PAGE_ALLOC_COSTLY_ORDER)?
-					     ISOLATE_BOTH : ISOLATE_INACTIVE,
-				zone, sc->mem_cgroup, 0);
-		nr_active = clear_active_flags(&page_list);
+			     &page_list, &nr_scan, sc->order, mode,
+				zone, sc->mem_cgroup, 0, file);
+		nr_active = clear_active_flags(&page_list, count);
 		__count_vm_events(PGDEACTIVATE, nr_active);
 
-		__mod_zone_page_state(zone, NR_ACTIVE, -nr_active);
-		__mod_zone_page_state(zone, NR_INACTIVE,
-						-(nr_taken - nr_active));
-		if (scan_global_lru(sc))
+		__mod_zone_page_state(zone, NR_ACTIVE_FILE,
+						-count[LRU_ACTIVE_FILE]);
+		__mod_zone_page_state(zone, NR_INACTIVE_FILE,
+						-count[LRU_INACTIVE_FILE]);
+		__mod_zone_page_state(zone, NR_ACTIVE_ANON,
+						-count[LRU_ACTIVE_ANON]);
+		__mod_zone_page_state(zone, NR_INACTIVE_ANON,
+						-count[LRU_INACTIVE_ANON]);
+
+		if (scan_global_lru(sc)) {
 			zone->pages_scanned += nr_scan;
+			zone->recent_scanned[0] += count[LRU_INACTIVE_ANON];
+			zone->recent_scanned[0] += count[LRU_ACTIVE_ANON];
+			zone->recent_scanned[1] += count[LRU_INACTIVE_FILE];
+			zone->recent_scanned[1] += count[LRU_ACTIVE_FILE];
+		}
 		spin_unlock_irq(&zone->lru_lock);
 
 		nr_scanned += nr_scan;
@@ -899,7 +1099,7 @@ static unsigned long shrink_inactive_list(unsigned long max_scan,
 			 * The attempt at page out may have made some
 			 * of the pages active, mark them inactive again.
 			 */
-			nr_active = clear_active_flags(&page_list);
+			nr_active = clear_active_flags(&page_list, count);
 			count_vm_events(PGDEACTIVATE, nr_active);
 
 			nr_freed += shrink_page_list(&page_list, sc,
@@ -924,14 +1124,24 @@ static unsigned long shrink_inactive_list(unsigned long max_scan,
 		 * Put back any unfreeable pages.
 		 */
 		while (!list_empty(&page_list)) {
+			int lru;
 			page = lru_to_page(&page_list);
 			VM_BUG_ON(PageLRU(page));
-			SetPageLRU(page);
 			list_del(&page->lru);
-			if (PageActive(page))
-				add_page_to_active_list(zone, page);
-			else
-				add_page_to_inactive_list(zone, page);
+			if (unlikely(!page_evictable(page, NULL))) {
+				spin_unlock_irq(&zone->lru_lock);
+				putback_lru_page(page);
+				spin_lock_irq(&zone->lru_lock);
+				continue;
+			}
+			SetPageLRU(page);
+			lru = page_lru(page);
+			add_page_to_lru_list(zone, page, lru);
+			mem_cgroup_move_lists(page, lru);
+			if (PageActive(page) && scan_global_lru(sc)) {
+				int file = !!page_is_file_cache(page);
+				zone->recent_rotated[file]++;
+			}
 			if (!pagevec_add(&pvec, page)) {
 				spin_unlock_irq(&zone->lru_lock);
 				__pagevec_release(&pvec);
@@ -962,115 +1172,7 @@ static inline void note_zone_scanning_priority(struct zone *zone, int priority)
 
 static inline int zone_is_near_oom(struct zone *zone)
 {
-	return zone->pages_scanned >= (zone_page_state(zone, NR_ACTIVE)
-				+ zone_page_state(zone, NR_INACTIVE))*3;
-}
-
-/*
- * Determine we should try to reclaim mapped pages.
- * This is called only when sc->mem_cgroup is NULL.
- */
-static int calc_reclaim_mapped(struct scan_control *sc, struct zone *zone,
-				int priority)
-{
-	long mapped_ratio;
-	long distress;
-	long swap_tendency;
-	long imbalance;
-	int reclaim_mapped = 0;
-	int prev_priority;
-
-	if (scan_global_lru(sc) && zone_is_near_oom(zone))
-		return 1;
-	/*
-	 * `distress' is a measure of how much trouble we're having
-	 * reclaiming pages.  0 -> no problems.  100 -> great trouble.
-	 */
-	if (scan_global_lru(sc))
-		prev_priority = zone->prev_priority;
-	else
-		prev_priority = mem_cgroup_get_reclaim_priority(sc->mem_cgroup);
-
-	distress = 100 >> min(prev_priority, priority);
-
-	/*
-	 * The point of this algorithm is to decide when to start
-	 * reclaiming mapped memory instead of just pagecache.  Work out
-	 * how much memory
-	 * is mapped.
-	 */
-	if (scan_global_lru(sc))
-		mapped_ratio = ((global_page_state(NR_FILE_MAPPED) +
-				global_page_state(NR_ANON_PAGES)) * 100) /
-					vm_total_pages;
-	else
-		mapped_ratio = mem_cgroup_calc_mapped_ratio(sc->mem_cgroup);
-
-	/*
-	 * Now decide how much we really want to unmap some pages.  The
-	 * mapped ratio is downgraded - just because there's a lot of
-	 * mapped memory doesn't necessarily mean that page reclaim
-	 * isn't succeeding.
-	 *
-	 * The distress ratio is important - we don't want to start
-	 * going oom.
-	 *
-	 * A 100% value of vm_swappiness overrides this algorithm
-	 * altogether.
-	 */
-	swap_tendency = mapped_ratio / 2 + distress + sc->swappiness;
-
-	/*
-	 * If there's huge imbalance between active and inactive
-	 * (think active 100 times larger than inactive) we should
-	 * become more permissive, or the system will take too much
-	 * cpu before it start swapping during memory pressure.
-	 * Distress is about avoiding early-oom, this is about
-	 * making swappiness graceful despite setting it to low
-	 * values.
-	 *
-	 * Avoid div by zero with nr_inactive+1, and max resulting
-	 * value is vm_total_pages.
-	 */
-	if (scan_global_lru(sc)) {
-		imbalance  = zone_page_state(zone, NR_ACTIVE);
-		imbalance /= zone_page_state(zone, NR_INACTIVE) + 1;
-	} else
-		imbalance = mem_cgroup_reclaim_imbalance(sc->mem_cgroup);
-
-	/*
-	 * Reduce the effect of imbalance if swappiness is low,
-	 * this means for a swappiness very low, the imbalance
-	 * must be much higher than 100 for this logic to make
-	 * the difference.
-	 *
-	 * Max temporary value is vm_total_pages*100.
-	 */
-	imbalance *= (vm_swappiness + 1);
-	imbalance /= 100;
-
-	/*
-	 * If not much of the ram is mapped, makes the imbalance
-	 * less relevant, it's high priority we refill the inactive
-	 * list with mapped pages only in presence of high ratio of
-	 * mapped pages.
-	 *
-	 * Max temporary value is vm_total_pages*100.
-	 */
-	imbalance *= mapped_ratio;
-	imbalance /= 100;
-
-	/* apply imbalance feedback to swap_tendency */
-	swap_tendency += imbalance;
-
-	/*
-	 * Now use this metric to decide whether to start moving mapped
-	 * memory onto the inactive list.
-	 */
-	if (swap_tendency >= 100)
-		reclaim_mapped = 1;
-
-	return reclaim_mapped;
+	return zone->pages_scanned >= (zone_lru_pages(zone) * 3);
 }
 
 /*
@@ -1093,53 +1195,71 @@ static int calc_reclaim_mapped(struct scan_control *sc, struct zone *zone,
 
 
 static void shrink_active_list(unsigned long nr_pages, struct zone *zone,
-				struct scan_control *sc, int priority)
+			struct scan_control *sc, int priority, int file)
 {
 	unsigned long pgmoved;
 	int pgdeactivate = 0;
 	unsigned long pgscanned;
 	LIST_HEAD(l_hold);	/* The pages which were snipped off */
-	LIST_HEAD(l_inactive);	/* Pages to go onto the inactive_list */
-	LIST_HEAD(l_active);	/* Pages to go onto the active_list */
+	LIST_HEAD(l_inactive);
 	struct page *page;
 	struct pagevec pvec;
-	int reclaim_mapped = 0;
-
-	if (sc->may_swap)
-		reclaim_mapped = calc_reclaim_mapped(sc, zone, priority);
+	enum lru_list lru;
 
 	lru_add_drain();
 	spin_lock_irq(&zone->lru_lock);
 	pgmoved = sc->isolate_pages(nr_pages, &l_hold, &pgscanned, sc->order,
 					ISOLATE_ACTIVE, zone,
-					sc->mem_cgroup, 1);
+					sc->mem_cgroup, 1, file);
 	/*
 	 * zone->pages_scanned is used for detect zone's oom
 	 * mem_cgroup remembers nr_scan by itself.
 	 */
-	if (scan_global_lru(sc))
+	if (scan_global_lru(sc)) {
 		zone->pages_scanned += pgscanned;
+		zone->recent_scanned[!!file] += pgmoved;
+	}
 
-	__mod_zone_page_state(zone, NR_ACTIVE, -pgmoved);
+	if (file)
+		__mod_zone_page_state(zone, NR_ACTIVE_FILE, -pgmoved);
+	else
+		__mod_zone_page_state(zone, NR_ACTIVE_ANON, -pgmoved);
 	spin_unlock_irq(&zone->lru_lock);
 
+	pgmoved = 0;
 	while (!list_empty(&l_hold)) {
 		cond_resched();
 		page = lru_to_page(&l_hold);
 		list_del(&page->lru);
-		if (page_mapped(page)) {
-			if (!reclaim_mapped ||
-			    (total_swap_pages == 0 && PageAnon(page)) ||
-			    page_referenced(page, 0, sc->mem_cgroup)) {
-				list_add(&page->lru, &l_active);
-				continue;
-			}
+
+		if (unlikely(!page_evictable(page, NULL))) {
+			putback_lru_page(page);
+			continue;
 		}
+
+		/* page_referenced clears PageReferenced */
+		if (page_mapping_inuse(page) &&
+		    page_referenced(page, 0, sc->mem_cgroup))
+			pgmoved++;
+
 		list_add(&page->lru, &l_inactive);
 	}
 
+	/*
+	 * Count referenced pages from currently used mappings as
+	 * rotated, even though they are moved to the inactive list.
+	 * This helps balance scan pressure between file and anonymous
+	 * pages in get_scan_ratio.
+	 */
+	zone->recent_rotated[!!file] += pgmoved;
+
+	/*
+	 * Move the pages to the [file or anon] inactive list.
+	 */
 	pagevec_init(&pvec, 1);
+
 	pgmoved = 0;
+	lru = LRU_BASE + file * LRU_FILE;
 	spin_lock_irq(&zone->lru_lock);
 	while (!list_empty(&l_inactive)) {
 		page = lru_to_page(&l_inactive);
@@ -1149,11 +1269,11 @@ static void shrink_active_list(unsigned long nr_pages, struct zone *zone,
 		VM_BUG_ON(!PageActive(page));
 		ClearPageActive(page);
 
-		list_move(&page->lru, &zone->inactive_list);
-		mem_cgroup_move_lists(page, false);
+		list_move(&page->lru, &zone->lru[lru].list);
+		mem_cgroup_move_lists(page, lru);
 		pgmoved++;
 		if (!pagevec_add(&pvec, page)) {
-			__mod_zone_page_state(zone, NR_INACTIVE, pgmoved);
+			__mod_zone_page_state(zone, NR_LRU_BASE + lru, pgmoved);
 			spin_unlock_irq(&zone->lru_lock);
 			pgdeactivate += pgmoved;
 			pgmoved = 0;
@@ -1163,104 +1283,189 @@ static void shrink_active_list(unsigned long nr_pages, struct zone *zone,
 			spin_lock_irq(&zone->lru_lock);
 		}
 	}
-	__mod_zone_page_state(zone, NR_INACTIVE, pgmoved);
+	__mod_zone_page_state(zone, NR_LRU_BASE + lru, pgmoved);
 	pgdeactivate += pgmoved;
 	if (buffer_heads_over_limit) {
 		spin_unlock_irq(&zone->lru_lock);
 		pagevec_strip(&pvec);
 		spin_lock_irq(&zone->lru_lock);
 	}
-
-	pgmoved = 0;
-	while (!list_empty(&l_active)) {
-		page = lru_to_page(&l_active);
-		prefetchw_prev_lru_page(page, &l_active, flags);
-		VM_BUG_ON(PageLRU(page));
-		SetPageLRU(page);
-		VM_BUG_ON(!PageActive(page));
-
-		list_move(&page->lru, &zone->active_list);
-		mem_cgroup_move_lists(page, true);
-		pgmoved++;
-		if (!pagevec_add(&pvec, page)) {
-			__mod_zone_page_state(zone, NR_ACTIVE, pgmoved);
-			pgmoved = 0;
-			spin_unlock_irq(&zone->lru_lock);
-			__pagevec_release(&pvec);
-			spin_lock_irq(&zone->lru_lock);
-		}
-	}
-	__mod_zone_page_state(zone, NR_ACTIVE, pgmoved);
-
 	__count_zone_vm_events(PGREFILL, zone, pgscanned);
 	__count_vm_events(PGDEACTIVATE, pgdeactivate);
 	spin_unlock_irq(&zone->lru_lock);
+	if (vm_swap_full())
+		pagevec_swap_free(&pvec);
 
 	pagevec_release(&pvec);
 }
 
+static unsigned long shrink_list(enum lru_list lru, unsigned long nr_to_scan,
+	struct zone *zone, struct scan_control *sc, int priority)
+{
+	int file = is_file_lru(lru);
+
+	if (lru == LRU_ACTIVE_FILE) {
+		shrink_active_list(nr_to_scan, zone, sc, priority, file);
+		return 0;
+	}
+
+	if (lru == LRU_ACTIVE_ANON &&
+	    (!scan_global_lru(sc) || inactive_anon_is_low(zone))) {
+		shrink_active_list(nr_to_scan, zone, sc, priority, file);
+		return 0;
+	}
+	return shrink_inactive_list(nr_to_scan, zone, sc, priority, file);
+}
+
+/*
+ * Determine how aggressively the anon and file LRU lists should be
+ * scanned.  The relative value of each set of LRU lists is determined
+ * by looking at the fraction of the pages scanned we did rotate back
+ * onto the active list instead of evict.
+ *
+ * percent[0] specifies how much pressure to put on ram/swap backed
+ * memory, while percent[1] determines pressure on the file LRUs.
+ */
+static void get_scan_ratio(struct zone *zone, struct scan_control *sc,
+					unsigned long *percent)
+{
+	unsigned long anon, file, free;
+	unsigned long anon_prio, file_prio;
+	unsigned long ap, fp;
+
+	anon  = zone_page_state(zone, NR_ACTIVE_ANON) +
+		zone_page_state(zone, NR_INACTIVE_ANON);
+	file  = zone_page_state(zone, NR_ACTIVE_FILE) +
+		zone_page_state(zone, NR_INACTIVE_FILE);
+	free  = zone_page_state(zone, NR_FREE_PAGES);
+
+	/* If we have no swap space, do not bother scanning anon pages. */
+	if (nr_swap_pages <= 0) {
+		percent[0] = 0;
+		percent[1] = 100;
+		return;
+	}
+
+	/* If we have very few page cache pages, force-scan anon pages. */
+	if (unlikely(file + free <= zone->pages_high)) {
+		percent[0] = 100;
+		percent[1] = 0;
+		return;
+	}
+
+	/*
+	 * OK, so we have swap space and a fair amount of page cache
+	 * pages.  We use the recently rotated / recently scanned
+	 * ratios to determine how valuable each cache is.
+	 *
+	 * Because workloads change over time (and to avoid overflow)
+	 * we keep these statistics as a floating average, which ends
+	 * up weighing recent references more than old ones.
+	 *
+	 * anon in [0], file in [1]
+	 */
+	if (unlikely(zone->recent_scanned[0] > anon / 4)) {
+		spin_lock_irq(&zone->lru_lock);
+		zone->recent_scanned[0] /= 2;
+		zone->recent_rotated[0] /= 2;
+		spin_unlock_irq(&zone->lru_lock);
+	}
+
+	if (unlikely(zone->recent_scanned[1] > file / 4)) {
+		spin_lock_irq(&zone->lru_lock);
+		zone->recent_scanned[1] /= 2;
+		zone->recent_rotated[1] /= 2;
+		spin_unlock_irq(&zone->lru_lock);
+	}
+
+	/*
+	 * With swappiness at 100, anonymous and file have the same priority.
+	 * This scanning priority is essentially the inverse of IO cost.
+	 */
+	anon_prio = sc->swappiness;
+	file_prio = 200 - sc->swappiness;
+
+	/*
+	 *                  anon       recent_rotated[0]
+	 * %anon = 100 * ----------- / ----------------- * IO cost
+	 *               anon + file      rotate_sum
+	 */
+	ap = (anon_prio + 1) * (zone->recent_scanned[0] + 1);
+	ap /= zone->recent_rotated[0] + 1;
+
+	fp = (file_prio + 1) * (zone->recent_scanned[1] + 1);
+	fp /= zone->recent_rotated[1] + 1;
+
+	/* Normalize to percentages */
+	percent[0] = 100 * ap / (ap + fp + 1);
+	percent[1] = 100 - percent[0];
+}
+
+
 /*
  * This is a basic per-zone page freer.  Used by both kswapd and direct reclaim.
  */
 static unsigned long shrink_zone(int priority, struct zone *zone,
 				struct scan_control *sc)
 {
-	unsigned long nr_active;
-	unsigned long nr_inactive;
+	unsigned long nr[NR_LRU_LISTS];
 	unsigned long nr_to_scan;
 	unsigned long nr_reclaimed = 0;
+	unsigned long percent[2];	/* anon @ 0; file @ 1 */
+	enum lru_list l;
 
-	if (scan_global_lru(sc)) {
-		/*
-		 * Add one to nr_to_scan just to make sure that the kernel
-		 * will slowly sift through the active list.
-		 */
-		zone->nr_scan_active +=
-			(zone_page_state(zone, NR_ACTIVE) >> priority) + 1;
-		nr_active = zone->nr_scan_active;
-		zone->nr_scan_inactive +=
-			(zone_page_state(zone, NR_INACTIVE) >> priority) + 1;
-		nr_inactive = zone->nr_scan_inactive;
-		if (nr_inactive >= sc->swap_cluster_max)
-			zone->nr_scan_inactive = 0;
-		else
-			nr_inactive = 0;
-
-		if (nr_active >= sc->swap_cluster_max)
-			zone->nr_scan_active = 0;
-		else
-			nr_active = 0;
-	} else {
-		/*
-		 * This reclaim occurs not because zone memory shortage but
-		 * because memory controller hits its limit.
-		 * Then, don't modify zone reclaim related data.
-		 */
-		nr_active = mem_cgroup_calc_reclaim_active(sc->mem_cgroup,
-					zone, priority);
-
-		nr_inactive = mem_cgroup_calc_reclaim_inactive(sc->mem_cgroup,
-					zone, priority);
-	}
+	get_scan_ratio(zone, sc, percent);
 
+	for_each_evictable_lru(l) {
+		if (scan_global_lru(sc)) {
+			int file = is_file_lru(l);
+			int scan;
 
-	while (nr_active || nr_inactive) {
-		if (nr_active) {
-			nr_to_scan = min(nr_active,
-					(unsigned long)sc->swap_cluster_max);
-			nr_active -= nr_to_scan;
-			shrink_active_list(nr_to_scan, zone, sc, priority);
+			scan = zone_page_state(zone, NR_LRU_BASE + l);
+			if (priority) {
+				scan >>= priority;
+				scan = (scan * percent[file]) / 100;
+			}
+			zone->lru[l].nr_scan += scan;
+			nr[l] = zone->lru[l].nr_scan;
+			if (nr[l] >= sc->swap_cluster_max)
+				zone->lru[l].nr_scan = 0;
+			else
+				nr[l] = 0;
+		} else {
+			/*
+			 * This reclaim occurs not because zone memory shortage
+			 * but because memory controller hits its limit.
+			 * Don't modify zone reclaim related data.
+			 */
+			nr[l] = mem_cgroup_calc_reclaim(sc->mem_cgroup, zone,
+								priority, l);
 		}
+	}
 
-		if (nr_inactive) {
-			nr_to_scan = min(nr_inactive,
+	while (nr[LRU_INACTIVE_ANON] || nr[LRU_ACTIVE_FILE] ||
+					nr[LRU_INACTIVE_FILE]) {
+		for_each_evictable_lru(l) {
+			if (nr[l]) {
+				nr_to_scan = min(nr[l],
 					(unsigned long)sc->swap_cluster_max);
-			nr_inactive -= nr_to_scan;
-			nr_reclaimed += shrink_inactive_list(nr_to_scan, zone,
-								sc);
+				nr[l] -= nr_to_scan;
+
+				nr_reclaimed += shrink_list(l, nr_to_scan,
+							zone, sc, priority);
+			}
 		}
 	}
 
+	/*
+	 * Even if we did not try to evict anon pages at all, we want to
+	 * rebalance the anon lru active/inactive ratio.
+	 */
+	if (!scan_global_lru(sc) || inactive_anon_is_low(zone))
+		shrink_active_list(SWAP_CLUSTER_MAX, zone, sc, priority, 0);
+	else if (!scan_global_lru(sc))
+		shrink_active_list(SWAP_CLUSTER_MAX, zone, sc, priority, 0);
+
 	throttle_vm_writeout(sc->gfp_mask);
 	return nr_reclaimed;
 }
@@ -1321,7 +1526,7 @@ static unsigned long shrink_zones(int priority, struct zonelist *zonelist,
 
 	return nr_reclaimed;
 }
- 
+
 /*
  * This is the main entry point to direct page reclaim.
  *
@@ -1364,8 +1569,7 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
 			if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
 				continue;
 
-			lru_pages += zone_page_state(zone, NR_ACTIVE)
-					+ zone_page_state(zone, NR_INACTIVE);
+			lru_pages += zone_lru_pages(zone);
 		}
 	}
 
@@ -1555,6 +1759,14 @@ loop_again:
 			    priority != DEF_PRIORITY)
 				continue;
 
+			/*
+			 * Do some background aging of the anon list, to give
+			 * pages a chance to be referenced before reclaiming.
+			 */
+			if (inactive_anon_is_low(zone))
+				shrink_active_list(SWAP_CLUSTER_MAX, zone,
+							&sc, priority, 0);
+
 			if (!zone_watermark_ok(zone, order, zone->pages_high,
 					       0, 0)) {
 				end_zone = i;
@@ -1567,8 +1779,7 @@ loop_again:
 		for (i = 0; i <= end_zone; i++) {
 			struct zone *zone = pgdat->node_zones + i;
 
-			lru_pages += zone_page_state(zone, NR_ACTIVE)
-					+ zone_page_state(zone, NR_INACTIVE);
+			lru_pages += zone_lru_pages(zone);
 		}
 
 		/*
@@ -1612,8 +1823,7 @@ loop_again:
 			if (zone_is_all_unreclaimable(zone))
 				continue;
 			if (nr_slab == 0 && zone->pages_scanned >=
-				(zone_page_state(zone, NR_ACTIVE)
-				+ zone_page_state(zone, NR_INACTIVE)) * 6)
+						(zone_lru_pages(zone) * 6))
 					zone_set_flag(zone,
 						      ZONE_ALL_UNRECLAIMABLE);
 			/*
@@ -1667,7 +1877,7 @@ out:
 
 /*
  * The background pageout daemon, started as a kernel thread
- * from the init process. 
+ * from the init process.
  *
  * This basically trickles out pages so that we have _some_
  * free memory available even if there is no other activity
@@ -1761,6 +1971,14 @@ void wakeup_kswapd(struct zone *zone, int order)
 	wake_up_interruptible(&pgdat->kswapd_wait);
 }
 
+unsigned long global_lru_pages(void)
+{
+	return global_page_state(NR_ACTIVE_ANON)
+		+ global_page_state(NR_ACTIVE_FILE)
+		+ global_page_state(NR_INACTIVE_ANON)
+		+ global_page_state(NR_INACTIVE_FILE);
+}
+
 #ifdef CONFIG_PM
 /*
  * Helper function for shrink_all_memory().  Tries to reclaim 'nr_pages' pages
@@ -1774,6 +1992,7 @@ static unsigned long shrink_all_zones(unsigned long nr_pages, int prio,
 {
 	struct zone *zone;
 	unsigned long nr_to_scan, ret = 0;
+	enum lru_list l;
 
 	for_each_zone(zone) {
 
@@ -1783,38 +2002,31 @@ static unsigned long shrink_all_zones(unsigned long nr_pages, int prio,
 		if (zone_is_all_unreclaimable(zone) && prio != DEF_PRIORITY)
 			continue;
 
-		/* For pass = 0 we don't shrink the active list */
-		if (pass > 0) {
-			zone->nr_scan_active +=
-				(zone_page_state(zone, NR_ACTIVE) >> prio) + 1;
-			if (zone->nr_scan_active >= nr_pages || pass > 3) {
-				zone->nr_scan_active = 0;
+		for_each_evictable_lru(l) {
+			/* For pass = 0, we don't shrink the active list */
+			if (pass == 0 &&
+				(l == LRU_ACTIVE || l == LRU_ACTIVE_FILE))
+				continue;
+
+			zone->lru[l].nr_scan +=
+				(zone_page_state(zone, NR_LRU_BASE + l)
+								>> prio) + 1;
+			if (zone->lru[l].nr_scan >= nr_pages || pass > 3) {
+				zone->lru[l].nr_scan = 0;
 				nr_to_scan = min(nr_pages,
-					zone_page_state(zone, NR_ACTIVE));
-				shrink_active_list(nr_to_scan, zone, sc, prio);
+					zone_page_state(zone,
+							NR_LRU_BASE + l));
+				ret += shrink_list(l, nr_to_scan, zone,
+								sc, prio);
+				if (ret >= nr_pages)
+					return ret;
 			}
 		}
-
-		zone->nr_scan_inactive +=
-			(zone_page_state(zone, NR_INACTIVE) >> prio) + 1;
-		if (zone->nr_scan_inactive >= nr_pages || pass > 3) {
-			zone->nr_scan_inactive = 0;
-			nr_to_scan = min(nr_pages,
-				zone_page_state(zone, NR_INACTIVE));
-			ret += shrink_inactive_list(nr_to_scan, zone, sc);
-			if (ret >= nr_pages)
-				return ret;
-		}
 	}
 
 	return ret;
 }
 
-static unsigned long count_lru_pages(void)
-{
-	return global_page_state(NR_ACTIVE) + global_page_state(NR_INACTIVE);
-}
-
 /*
  * Try to free `nr_pages' of memory, system-wide, and return the number of
  * freed pages.
@@ -1840,7 +2052,7 @@ unsigned long shrink_all_memory(unsigned long nr_pages)
 
 	current->reclaim_state = &reclaim_state;
 
-	lru_pages = count_lru_pages();
+	lru_pages = global_lru_pages();
 	nr_slab = global_page_state(NR_SLAB_RECLAIMABLE);
 	/* If slab caches are huge, it's better to hit them first */
 	while (nr_slab >= lru_pages) {
@@ -1883,7 +2095,7 @@ unsigned long shrink_all_memory(unsigned long nr_pages)
 
 			reclaim_state.reclaimed_slab = 0;
 			shrink_slab(sc.nr_scanned, sc.gfp_mask,
-					count_lru_pages());
+					global_lru_pages());
 			ret += reclaim_state.reclaimed_slab;
 			if (ret >= nr_pages)
 				goto out;
@@ -1900,7 +2112,7 @@ unsigned long shrink_all_memory(unsigned long nr_pages)
 	if (!ret) {
 		do {
 			reclaim_state.reclaimed_slab = 0;
-			shrink_slab(nr_pages, sc.gfp_mask, count_lru_pages());
+			shrink_slab(nr_pages, sc.gfp_mask, global_lru_pages());
 			ret += reclaim_state.reclaimed_slab;
 		} while (ret < nr_pages && reclaim_state.reclaimed_slab > 0);
 	}
@@ -2128,3 +2340,285 @@ int zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
 	return ret;
 }
 #endif
+
+#ifdef CONFIG_UNEVICTABLE_LRU
+/*
+ * page_evictable - test whether a page is evictable
+ * @page: the page to test
+ * @vma: the VMA in which the page is or will be mapped, may be NULL
+ *
+ * Test whether page is evictable--i.e., should be placed on active/inactive
+ * lists vs unevictable list.  The vma argument is !NULL when called from the
+ * fault path to determine how to instantate a new page.
+ *
+ * Reasons page might not be evictable:
+ * (1) page's mapping marked unevictable
+ * (2) page is part of an mlocked VMA
+ *
+ */
+int page_evictable(struct page *page, struct vm_area_struct *vma)
+{
+
+	if (mapping_unevictable(page_mapping(page)))
+		return 0;
+
+	if (PageMlocked(page) || (vma && is_mlocked_vma(vma, page)))
+		return 0;
+
+	return 1;
+}
+
+static void show_page_path(struct page *page)
+{
+	char buf[256];
+	if (page_is_file_cache(page)) {
+		struct address_space *mapping = page->mapping;
+		struct dentry *dentry;
+		pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
+
+		spin_lock(&mapping->i_mmap_lock);
+		dentry = d_find_alias(mapping->host);
+		printk(KERN_INFO "rescued: %s %lu\n",
+		       dentry_path(dentry, buf, 256), pgoff);
+		spin_unlock(&mapping->i_mmap_lock);
+	} else {
+#if defined(CONFIG_MM_OWNER) && defined(CONFIG_MMU)
+		struct anon_vma *anon_vma;
+		struct vm_area_struct *vma;
+
+		anon_vma = page_lock_anon_vma(page);
+		if (!anon_vma)
+			return;
+
+		list_for_each_entry(vma, &anon_vma->head, anon_vma_node) {
+			printk(KERN_INFO "rescued: anon %s\n",
+			       vma->vm_mm->owner->comm);
+			break;
+		}
+		page_unlock_anon_vma(anon_vma);
+#endif
+	}
+}
+
+
+/**
+ * check_move_unevictable_page - check page for evictability and move to appropriate zone lru list
+ * @page: page to check evictability and move to appropriate lru list
+ * @zone: zone page is in
+ *
+ * Checks a page for evictability and moves the page to the appropriate
+ * zone lru list.
+ *
+ * Restrictions: zone->lru_lock must be held, page must be on LRU and must
+ * have PageUnevictable set.
+ */
+static void check_move_unevictable_page(struct page *page, struct zone *zone)
+{
+	VM_BUG_ON(PageActive(page));
+
+retry:
+	ClearPageUnevictable(page);
+	if (page_evictable(page, NULL)) {
+		enum lru_list l = LRU_INACTIVE_ANON + page_is_file_cache(page);
+
+		show_page_path(page);
+
+		__dec_zone_state(zone, NR_UNEVICTABLE);
+		list_move(&page->lru, &zone->lru[l].list);
+		__inc_zone_state(zone, NR_INACTIVE_ANON + l);
+		__count_vm_event(UNEVICTABLE_PGRESCUED);
+	} else {
+		/*
+		 * rotate unevictable list
+		 */
+		SetPageUnevictable(page);
+		list_move(&page->lru, &zone->lru[LRU_UNEVICTABLE].list);
+		if (page_evictable(page, NULL))
+			goto retry;
+	}
+}
+
+/**
+ * scan_mapping_unevictable_pages - scan an address space for evictable pages
+ * @mapping: struct address_space to scan for evictable pages
+ *
+ * Scan all pages in mapping.  Check unevictable pages for
+ * evictability and move them to the appropriate zone lru list.
+ */
+void scan_mapping_unevictable_pages(struct address_space *mapping)
+{
+	pgoff_t next = 0;
+	pgoff_t end   = (i_size_read(mapping->host) + PAGE_CACHE_SIZE - 1) >>
+			 PAGE_CACHE_SHIFT;
+	struct zone *zone;
+	struct pagevec pvec;
+
+	if (mapping->nrpages == 0)
+		return;
+
+	pagevec_init(&pvec, 0);
+	while (next < end &&
+		pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
+		int i;
+		int pg_scanned = 0;
+
+		zone = NULL;
+
+		for (i = 0; i < pagevec_count(&pvec); i++) {
+			struct page *page = pvec.pages[i];
+			pgoff_t page_index = page->index;
+			struct zone *pagezone = page_zone(page);
+
+			pg_scanned++;
+			if (page_index > next)
+				next = page_index;
+			next++;
+
+			if (pagezone != zone) {
+				if (zone)
+					spin_unlock_irq(&zone->lru_lock);
+				zone = pagezone;
+				spin_lock_irq(&zone->lru_lock);
+			}
+
+			if (PageLRU(page) && PageUnevictable(page))
+				check_move_unevictable_page(page, zone);
+		}
+		if (zone)
+			spin_unlock_irq(&zone->lru_lock);
+		pagevec_release(&pvec);
+
+		count_vm_events(UNEVICTABLE_PGSCANNED, pg_scanned);
+	}
+
+}
+
+/**
+ * scan_zone_unevictable_pages - check unevictable list for evictable pages
+ * @zone - zone of which to scan the unevictable list
+ *
+ * Scan @zone's unevictable LRU lists to check for pages that have become
+ * evictable.  Move those that have to @zone's inactive list where they
+ * become candidates for reclaim, unless shrink_inactive_zone() decides
+ * to reactivate them.  Pages that are still unevictable are rotated
+ * back onto @zone's unevictable list.
+ */
+#define SCAN_UNEVICTABLE_BATCH_SIZE 16UL /* arbitrary lock hold batch size */
+void scan_zone_unevictable_pages(struct zone *zone)
+{
+	struct list_head *l_unevictable = &zone->lru[LRU_UNEVICTABLE].list;
+	unsigned long scan;
+	unsigned long nr_to_scan = zone_page_state(zone, NR_UNEVICTABLE);
+
+	while (nr_to_scan > 0) {
+		unsigned long batch_size = min(nr_to_scan,
+						SCAN_UNEVICTABLE_BATCH_SIZE);
+
+		spin_lock_irq(&zone->lru_lock);
+		for (scan = 0;  scan < batch_size; scan++) {
+			struct page *page = lru_to_page(l_unevictable);
+
+			if (!trylock_page(page))
+				continue;
+
+			prefetchw_prev_lru_page(page, l_unevictable, flags);
+
+			if (likely(PageLRU(page) && PageUnevictable(page)))
+				check_move_unevictable_page(page, zone);
+
+			unlock_page(page);
+		}
+		spin_unlock_irq(&zone->lru_lock);
+
+		nr_to_scan -= batch_size;
+	}
+}
+
+
+/**
+ * scan_all_zones_unevictable_pages - scan all unevictable lists for evictable pages
+ *
+ * A really big hammer:  scan all zones' unevictable LRU lists to check for
+ * pages that have become evictable.  Move those back to the zones'
+ * inactive list where they become candidates for reclaim.
+ * This occurs when, e.g., we have unswappable pages on the unevictable lists,
+ * and we add swap to the system.  As such, it runs in the context of a task
+ * that has possibly/probably made some previously unevictable pages
+ * evictable.
+ */
+void scan_all_zones_unevictable_pages(void)
+{
+	struct zone *zone;
+
+	for_each_zone(zone) {
+		scan_zone_unevictable_pages(zone);
+	}
+}
+
+/*
+ * scan_unevictable_pages [vm] sysctl handler.  On demand re-scan of
+ * all nodes' unevictable lists for evictable pages
+ */
+unsigned long scan_unevictable_pages;
+
+int scan_unevictable_handler(struct ctl_table *table, int write,
+			   struct file *file, void __user *buffer,
+			   size_t *length, loff_t *ppos)
+{
+	proc_doulongvec_minmax(table, write, file, buffer, length, ppos);
+
+	if (write && *(unsigned long *)table->data)
+		scan_all_zones_unevictable_pages();
+
+	scan_unevictable_pages = 0;
+	return 0;
+}
+
+/*
+ * per node 'scan_unevictable_pages' attribute.  On demand re-scan of
+ * a specified node's per zone unevictable lists for evictable pages.
+ */
+
+static ssize_t read_scan_unevictable_node(struct sys_device *dev,
+					  struct sysdev_attribute *attr,
+					  char *buf)
+{
+	return sprintf(buf, "0\n");	/* always zero; should fit... */
+}
+
+static ssize_t write_scan_unevictable_node(struct sys_device *dev,
+					   struct sysdev_attribute *attr,
+					const char *buf, size_t count)
+{
+	struct zone *node_zones = NODE_DATA(dev->id)->node_zones;
+	struct zone *zone;
+	unsigned long res;
+	unsigned long req = strict_strtoul(buf, 10, &res);
+
+	if (!req)
+		return 1;	/* zero is no-op */
+
+	for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) {
+		if (!populated_zone(zone))
+			continue;
+		scan_zone_unevictable_pages(zone);
+	}
+	return 1;
+}
+
+
+static SYSDEV_ATTR(scan_unevictable_pages, S_IRUGO | S_IWUSR,
+			read_scan_unevictable_node,
+			write_scan_unevictable_node);
+
+int scan_unevictable_register_node(struct node *node)
+{
+	return sysdev_create_file(&node->sysdev, &attr_scan_unevictable_pages);
+}
+
+void scan_unevictable_unregister_node(struct node *node)
+{
+	sysdev_remove_file(&node->sysdev, &attr_scan_unevictable_pages);
+}
+
+#endif