1 files changed, 257 insertions, 65 deletions

diff --git a/mm/swap.c b/mm/swap.c
index 3f48542..bbc1ce9 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -56,17 +56,97 @@ static void __page_cache_release(struct page *page)
 		del_page_from_lru(zone, page);
 		spin_unlock_irqrestore(&zone->lru_lock, flags);
 	}
+}
+
+static void __put_single_page(struct page *page)
+{
+	__page_cache_release(page);
 	free_hot_cold_page(page, 0);
 }
 
-static void put_compound_page(struct page *page)
+static void __put_compound_page(struct page *page)
 {
-	page = compound_head(page);
-	if (put_page_testzero(page)) {
-		compound_page_dtor *dtor;
+	compound_page_dtor *dtor;
 
-		dtor = get_compound_page_dtor(page);
-		(*dtor)(page);
+	__page_cache_release(page);
+	dtor = get_compound_page_dtor(page);
+	(*dtor)(page);
+}
+
+static void put_compound_page(struct page *page)
+{
+	if (unlikely(PageTail(page))) {
+		/* __split_huge_page_refcount can run under us */
+		struct page *page_head = page->first_page;
+		smp_rmb();
+		/*
+		 * If PageTail is still set after smp_rmb() we can be sure
+		 * that the page->first_page we read wasn't a dangling pointer.
+		 * See __split_huge_page_refcount() smp_wmb().
+		 */
+		if (likely(PageTail(page) && get_page_unless_zero(page_head))) {
+			unsigned long flags;
+			/*
+			 * Verify that our page_head wasn't converted
+			 * to a a regular page before we got a
+			 * reference on it.
+			 */
+			if (unlikely(!PageHead(page_head))) {
+				/* PageHead is cleared after PageTail */
+				smp_rmb();
+				VM_BUG_ON(PageTail(page));
+				goto out_put_head;
+			}
+			/*
+			 * Only run compound_lock on a valid PageHead,
+			 * after having it pinned with
+			 * get_page_unless_zero() above.
+			 */
+			smp_mb();
+			/* page_head wasn't a dangling pointer */
+			flags = compound_lock_irqsave(page_head);
+			if (unlikely(!PageTail(page))) {
+				/* __split_huge_page_refcount run before us */
+				compound_unlock_irqrestore(page_head, flags);
+				VM_BUG_ON(PageHead(page_head));
+			out_put_head:
+				if (put_page_testzero(page_head))
+					__put_single_page(page_head);
+			out_put_single:
+				if (put_page_testzero(page))
+					__put_single_page(page);
+				return;
+			}
+			VM_BUG_ON(page_head != page->first_page);
+			/*
+			 * We can release the refcount taken by
+			 * get_page_unless_zero now that
+			 * split_huge_page_refcount is blocked on the
+			 * compound_lock.
+			 */
+			if (put_page_testzero(page_head))
+				VM_BUG_ON(1);
+			/* __split_huge_page_refcount will wait now */
+			VM_BUG_ON(atomic_read(&page->_count) <= 0);
+			atomic_dec(&page->_count);
+			VM_BUG_ON(atomic_read(&page_head->_count) <= 0);
+			compound_unlock_irqrestore(page_head, flags);
+			if (put_page_testzero(page_head)) {
+				if (PageHead(page_head))
+					__put_compound_page(page_head);
+				else
+					__put_single_page(page_head);
+			}
+		} else {
+			/* page_head is a dangling pointer */
+			VM_BUG_ON(PageTail(page));
+			goto out_put_single;
+		}
+	} else if (put_page_testzero(page)) {
+		if (PageHead(page))
+			__put_compound_page(page);
+		else
+			__put_single_page(page);
 	}
 }
 
@@ -75,7 +155,7 @@ void put_page(struct page *page)
 	if (unlikely(PageCompound(page)))
 		put_compound_page(page);
 	else if (put_page_testzero(page))
-		__page_cache_release(page);
+		__put_single_page(page);
 }
 EXPORT_SYMBOL(put_page);
 
@@ -98,15 +178,13 @@ void put_pages_list(struct list_head *pages)
 }
 EXPORT_SYMBOL(put_pages_list);
 
-/*
- * pagevec_move_tail() must be called with IRQ disabled.
- * Otherwise this may cause nasty races.
- */
-static void pagevec_move_tail(struct pagevec *pvec)
+static void pagevec_lru_move_fn(struct pagevec *pvec,
+				void (*move_fn)(struct page *page, void *arg),
+				void *arg)
 {
 	int i;
-	int pgmoved = 0;
 	struct zone *zone = NULL;
+	unsigned long flags = 0;
 
 	for (i = 0; i < pagevec_count(pvec); i++) {
 		struct page *page = pvec->pages[i];
@@ -114,29 +192,49 @@ static void pagevec_move_tail(struct pagevec *pvec)
 
 		if (pagezone != zone) {
 			if (zone)
-				spin_unlock(&zone->lru_lock);
+				spin_unlock_irqrestore(&zone->lru_lock, flags);
 			zone = pagezone;
-			spin_lock(&zone->lru_lock);
-		}
-		if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
-			int lru = page_lru_base_type(page);
-			list_move_tail(&page->lru, &zone->lru[lru].list);
-			pgmoved++;
+			spin_lock_irqsave(&zone->lru_lock, flags);
 		}
+
+		(*move_fn)(page, arg);
 	}
 	if (zone)
-		spin_unlock(&zone->lru_lock);
-	__count_vm_events(PGROTATED, pgmoved);
-	release_pages(pvec->pages, pvec->nr, pvec->cold);
+		spin_unlock_irqrestore(&zone->lru_lock, flags);
+	release_pages(pvec->pages, pagevec_count(pvec), pvec->cold);
 	pagevec_reinit(pvec);
 }
 
+static void pagevec_move_tail_fn(struct page *page, void *arg)
+{
+	int *pgmoved = arg;
+	struct zone *zone = page_zone(page);
+
+	if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
+		int lru = page_lru_base_type(page);
+		list_move_tail(&page->lru, &zone->lru[lru].list);
+		(*pgmoved)++;
+	}
+}
+
+/*
+ * pagevec_move_tail() must be called with IRQ disabled.
+ * Otherwise this may cause nasty races.
+ */
+static void pagevec_move_tail(struct pagevec *pvec)
+{
+	int pgmoved = 0;
+
+	pagevec_lru_move_fn(pvec, pagevec_move_tail_fn, &pgmoved);
+	__count_vm_events(PGROTATED, pgmoved);
+}
+
 /*
  * Writeback is about to end against a page which has been marked for immediate
  * reclaim.  If it still appears to be reclaimable, move it to the tail of the
  * inactive list.
  */
-void  rotate_reclaimable_page(struct page *page)
+void rotate_reclaimable_page(struct page *page)
 {
 	if (!PageLocked(page) && !PageDirty(page) && !PageActive(page) &&
 	    !PageUnevictable(page) && PageLRU(page)) {
@@ -173,27 +271,94 @@ static void update_page_reclaim_stat(struct zone *zone, struct page *page,
 }
 
 /*
- * FIXME: speed this up?
+ * A page will go to active list either by activate_page or putback_lru_page.
+ * In the activate_page case, the page hasn't active bit set. The page might
+ * not in LRU list because it's isolated before it gets a chance to be moved to
+ * active list. The window is small because pagevec just stores several pages.
+ * For such case, we do nothing for such page.
+ * In the putback_lru_page case, the page isn't in lru list but has active
+ * bit set
  */
-void activate_page(struct page *page)
+static void __activate_page(struct page *page, void *arg)
 {
 	struct zone *zone = page_zone(page);
+	int file = page_is_file_cache(page);
+	int lru = page_lru_base_type(page);
+	bool putback = !PageLRU(page);
 
-	spin_lock_irq(&zone->lru_lock);
-	if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
-		int file = page_is_file_cache(page);
-		int lru = page_lru_base_type(page);
+	/* The page is isolated before it's moved to active list */
+	if (!PageLRU(page) && !PageActive(page))
+		return;
+	if ((PageLRU(page) && PageActive(page)) || PageUnevictable(page))
+		return;
+
+	if (!putback)
 		del_page_from_lru_list(zone, page, lru);
+	else
+		SetPageLRU(page);
 
-		SetPageActive(page);
-		lru += LRU_ACTIVE;
-		add_page_to_lru_list(zone, page, lru);
-		__count_vm_event(PGACTIVATE);
+	SetPageActive(page);
+	lru += LRU_ACTIVE;
+	add_page_to_lru_list(zone, page, lru);
 
-		update_page_reclaim_stat(zone, page, file, 1);
+	if (putback)
+		return;
+	__count_vm_event(PGACTIVATE);
+	update_page_reclaim_stat(zone, page, file, 1);
+}
+
+#ifdef CONFIG_SMP
+static DEFINE_PER_CPU(struct pagevec, activate_page_pvecs);
+
+static void activate_page_drain(int cpu)
+{
+	struct pagevec *pvec = &per_cpu(activate_page_pvecs, cpu);
+
+	if (pagevec_count(pvec))
+		pagevec_lru_move_fn(pvec, __activate_page, NULL);
+}
+
+void activate_page(struct page *page)
+{
+	if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
+		struct pagevec *pvec = &get_cpu_var(activate_page_pvecs);
+
+		page_cache_get(page);
+		if (!pagevec_add(pvec, page))
+			pagevec_lru_move_fn(pvec, __activate_page, NULL);
+		put_cpu_var(activate_page_pvecs);
+	}
+}
+
+/* Caller should hold zone->lru_lock */
+int putback_active_lru_page(struct zone *zone, struct page *page)
+{
+	struct pagevec *pvec = &get_cpu_var(activate_page_pvecs);
+
+	if (!pagevec_add(pvec, page)) {
+		spin_unlock_irq(&zone->lru_lock);
+		pagevec_lru_move_fn(pvec, __activate_page, NULL);
+		spin_lock_irq(&zone->lru_lock);
 	}
+	put_cpu_var(activate_page_pvecs);
+	return 1;
+}
+
+#else
+static inline void activate_page_drain(int cpu)
+{
+}
+
+void activate_page(struct page *page)
+{
+	struct zone *zone = page_zone(page);
+
+	spin_lock_irq(&zone->lru_lock);
+	if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page))
+		__activate_page(page, NULL);
 	spin_unlock_irq(&zone->lru_lock);
 }
+#endif
 
 /*
  * Mark a page as having seen activity.
@@ -292,6 +457,7 @@ static void drain_cpu_pagevecs(int cpu)
 		pagevec_move_tail(pvec);
 		local_irq_restore(flags);
 	}
+	activate_page_drain(cpu);
 }
 
 void lru_add_drain(void)
@@ -399,44 +565,70 @@ void __pagevec_release(struct pagevec *pvec)
 
 EXPORT_SYMBOL(__pagevec_release);
 
+/* used by __split_huge_page_refcount() */
+void lru_add_page_tail(struct zone* zone,
+		       struct page *page, struct page *page_tail)
+{
+	int active;
+	enum lru_list lru;
+	const int file = 0;
+	struct list_head *head;
+
+	VM_BUG_ON(!PageHead(page));
+	VM_BUG_ON(PageCompound(page_tail));
+	VM_BUG_ON(PageLRU(page_tail));
+	VM_BUG_ON(!spin_is_locked(&zone->lru_lock));
+
+	SetPageLRU(page_tail);
+
+	if (page_evictable(page_tail, NULL)) {
+		if (PageActive(page)) {
+			SetPageActive(page_tail);
+			active = 1;
+			lru = LRU_ACTIVE_ANON;
+		} else {
+			active = 0;
+			lru = LRU_INACTIVE_ANON;
+		}
+		update_page_reclaim_stat(zone, page_tail, file, active);
+		if (likely(PageLRU(page)))
+			head = page->lru.prev;
+		else
+			head = &zone->lru[lru].list;
+		__add_page_to_lru_list(zone, page_tail, lru, head);
+	} else {
+		SetPageUnevictable(page_tail);
+		add_page_to_lru_list(zone, page_tail, LRU_UNEVICTABLE);
+	}
+}
+
+static void ____pagevec_lru_add_fn(struct page *page, void *arg)
+{
+	enum lru_list lru = (enum lru_list)arg;
+	struct zone *zone = page_zone(page);
+	int file = is_file_lru(lru);
+	int active = is_active_lru(lru);
+
+	VM_BUG_ON(PageActive(page));
+	VM_BUG_ON(PageUnevictable(page));
+	VM_BUG_ON(PageLRU(page));
+
+	SetPageLRU(page);
+	if (active)
+		SetPageActive(page);
+	update_page_reclaim_stat(zone, page, file, active);
+	add_page_to_lru_list(zone, page, lru);
+}
+
 /*
  * Add the passed pages to the LRU, then drop the caller's refcount
  * on them.  Reinitialises the caller's pagevec.
  */
 void ____pagevec_lru_add(struct pagevec *pvec, enum lru_list lru)
 {
-	int i;
-	struct zone *zone = NULL;
-
 	VM_BUG_ON(is_unevictable_lru(lru));
 
-	for (i = 0; i < pagevec_count(pvec); i++) {
-		struct page *page = pvec->pages[i];
-		struct zone *pagezone = page_zone(page);
-		int file;
-		int active;
-
-		if (pagezone != zone) {
-			if (zone)
-				spin_unlock_irq(&zone->lru_lock);
-			zone = pagezone;
-			spin_lock_irq(&zone->lru_lock);
-		}
-		VM_BUG_ON(PageActive(page));
-		VM_BUG_ON(PageUnevictable(page));
-		VM_BUG_ON(PageLRU(page));
-		SetPageLRU(page);
-		active = is_active_lru(lru);
-		file = is_file_lru(lru);
-		if (active)
-			SetPageActive(page);
-		update_page_reclaim_stat(zone, page, file, active);
-		add_page_to_lru_list(zone, page, lru);
-	}
-	if (zone)
-		spin_unlock_irq(&zone->lru_lock);
-	release_pages(pvec->pages, pvec->nr, pvec->cold);
-	pagevec_reinit(pvec);
+	pagevec_lru_move_fn(pvec, ____pagevec_lru_add_fn, (void *)lru);
 }
 
 EXPORT_SYMBOL(____pagevec_lru_add);