---

yaml
---
r: 115837
b: refs/heads/master
c: 68a2239
h: refs/heads/master
i:
  115835: 00cabe7
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: f04e9ebbe4909f9a41efd55149bc353299f4e83b
+refs/heads/master: 68a22394c286a2daf06ee8d65d8835f738faefa5

trunk/include/linux/pagevec.h

@@ -25,6 +25,7 @@ void __pagevec_release_nonlru(struct pagevec *pvec);
 void __pagevec_free(struct pagevec *pvec);
 void ____pagevec_lru_add(struct pagevec *pvec, enum lru_list lru);
 void pagevec_strip(struct pagevec *pvec);
+void pagevec_swap_free(struct pagevec *pvec);
 unsigned pagevec_lookup(struct pagevec *pvec, struct address_space *mapping,
 		pgoff_t start, unsigned nr_pages);
 unsigned pagevec_lookup_tag(struct pagevec *pvec,

trunk/include/linux/swap.h

@@ -265,6 +265,7 @@ extern sector_t swapdev_block(int, pgoff_t);
 extern struct swap_info_struct *get_swap_info_struct(unsigned);
 extern int can_share_swap_page(struct page *);
 extern int remove_exclusive_swap_page(struct page *);
+extern int remove_exclusive_swap_page_ref(struct page *);
 struct backing_dev_info;
 
 /* linux/mm/thrash.c */
@@ -353,6 +354,11 @@ static inline int remove_exclusive_swap_page(struct page *p)
 	return 0;
 }
 
+static inline int remove_exclusive_swap_page_ref(struct page *page)
+{
+	return 0;
+}
+
 static inline swp_entry_t get_swap_page(void)
 {
 	swp_entry_t entry;

trunk/mm/swap.c

@@ -427,6 +427,30 @@ void pagevec_strip(struct pagevec *pvec)
 	}
 }
 
+/**
+ * pagevec_swap_free - try to free swap space from the pages in a pagevec
+ * @pvec: pagevec with swapcache pages to free the swap space of
+ *
+ * The caller needs to hold an extra reference to each page and
+ * not hold the page lock on the pages.  This function uses a
+ * trylock on the page lock so it may not always free the swap
+ * space associated with a page.
+ */
+void pagevec_swap_free(struct pagevec *pvec)
+{
+	int i;
+
+	for (i = 0; i < pagevec_count(pvec); i++) {
+		struct page *page = pvec->pages[i];
+
+		if (PageSwapCache(page) && trylock_page(page)) {
+			if (PageSwapCache(page))
+				remove_exclusive_swap_page_ref(page);
+			unlock_page(page);
+		}
+	}
+}
+
 /**
  * pagevec_lookup - gang pagecache lookup
  * @pvec:	Where the resulting pages are placed

trunk/mm/swapfile.c

@@ -344,7 +344,7 @@ int can_share_swap_page(struct page *page)
  * Work out if there are any other processes sharing this
  * swap cache page. Free it if you can. Return success.
  */
-int remove_exclusive_swap_page(struct page *page)
+static int remove_exclusive_swap_page_count(struct page *page, int count)
 {
 	int retval;
 	struct swap_info_struct * p;
@@ -357,7 +357,7 @@ int remove_exclusive_swap_page(struct page *page)
 		return 0;
 	if (PageWriteback(page))
 		return 0;
-	if (page_count(page) != 2) /* 2: us + cache */
+	if (page_count(page) != count) /* us + cache + ptes */
 		return 0;
 
 	entry.val = page_private(page);
@@ -370,7 +370,7 @@ int remove_exclusive_swap_page(struct page *page)
 	if (p->swap_map[swp_offset(entry)] == 1) {
 		/* Recheck the page count with the swapcache lock held.. */
 		spin_lock_irq(&swapper_space.tree_lock);
-		if ((page_count(page) == 2) && !PageWriteback(page)) {
+		if ((page_count(page) == count) && !PageWriteback(page)) {
 			__delete_from_swap_cache(page);
 			SetPageDirty(page);
 			retval = 1;
@@ -387,6 +387,25 @@ int remove_exclusive_swap_page(struct page *page)
 	return retval;
 }
 
+/*
+ * Most of the time the page should have two references: one for the
+ * process and one for the swap cache.
+ */
+int remove_exclusive_swap_page(struct page *page)
+{
+	return remove_exclusive_swap_page_count(page, 2);
+}
+
+/*
+ * The pageout code holds an extra reference to the page.  That raises
+ * the reference count to test for to 2 for a page that is only in the
+ * swap cache plus 1 for each process that maps the page.
+ */
+int remove_exclusive_swap_page_ref(struct page *page)
+{
+	return remove_exclusive_swap_page_count(page, 2 + page_mapcount(page));
+}
+
 /*
  * Free the swap entry like above, but also try to
  * free the page cache entry if it is the last user.

trunk/mm/vmscan.c

@@ -647,6 +647,9 @@ static unsigned long shrink_page_list(struct list_head *page_list,
 		continue;
 
 activate_locked:
+		/* Not a candidate for swapping, so reclaim swap space. */
+		if (PageSwapCache(page) && vm_swap_full())
+			remove_exclusive_swap_page_ref(page);
 		SetPageActive(page);
 		pgactivate++;
 keep_locked:
@@ -1228,6 +1231,8 @@ static void shrink_active_list(unsigned long nr_pages, struct zone *zone,
 			__mod_zone_page_state(zone, NR_ACTIVE, pgmoved);
 			pgmoved = 0;
 			spin_unlock_irq(&zone->lru_lock);
+			if (vm_swap_full())
+				pagevec_swap_free(&pvec);
 			__pagevec_release(&pvec);
 			spin_lock_irq(&zone->lru_lock);
 		}
@@ -1237,6 +1242,8 @@ static void shrink_active_list(unsigned long nr_pages, struct zone *zone,
 	__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);
 }