1 files changed, 20 insertions, 14 deletions

diff --git a/mm/swapfile.c b/mm/swapfile.c
index 98d348347..dddefaeaa 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -48,6 +48,12 @@ static void free_swap_count_continuations(struct swap_info_struct *);
 DEFINE_SPINLOCK(swap_lock);
 static unsigned int nr_swapfiles;
 atomic_long_t nr_swap_pages;
+/*
+ * Some modules use swappable objects and may try to swap them out under
+ * memory pressure (via the shrinker). Before doing so, they may wish to
+ * check to see if any swap space is available.
+ */
+EXPORT_SYMBOL_GPL(nr_swap_pages);
 /* protected with swap_lock. reading in vm_swap_full() doesn't need lock */
 long total_swap_pages;
 static int least_priority;
@@ -113,7 +119,7 @@ __try_to_reclaim_swap(struct swap_info_struct *si, unsigned long offset)
 		ret = try_to_free_swap(page);
 		unlock_page(page);
 	}
-	page_cache_release(page);
+	put_page(page);
 	return ret;
 }
 
@@ -970,18 +976,19 @@ out:
  * to it.  And as a side-effect, free up its swap: because the old content
  * on disk will never be read, and seeking back there to write new content
  * later would only waste time away from clustering.
+ *
+ * NOTE: total_mapcount should not be relied upon by the caller if
+ * reuse_swap_page() returns false, but it may be always overwritten
+ * (see the other implementation for CONFIG_SWAP=n).
  */
-int reuse_swap_page(struct page *page)
+bool reuse_swap_page(struct page *page, int *total_mapcount)
 {
 	int count;
 
 	VM_BUG_ON_PAGE(!PageLocked(page), page);
 	if (unlikely(PageKsm(page)))
-		return 0;
-	/* The page is part of THP and cannot be reused */
-	if (PageTransCompound(page))
-		return 0;
-	count = page_mapcount(page);
+		return false;
+	count = page_trans_huge_mapcount(page, total_mapcount);
 	if (count <= 1 && PageSwapCache(page)) {
 		count += page_swapcount(page);
 		if (count == 1 && !PageWriteback(page)) {
@@ -1048,7 +1055,7 @@ int free_swap_and_cache(swp_entry_t entry)
 			page = find_get_page(swap_address_space(entry),
 						entry.val);
 			if (page && !trylock_page(page)) {
-				page_cache_release(page);
+				put_page(page);
 				page = NULL;
 			}
 		}
@@ -1065,7 +1072,7 @@ int free_swap_and_cache(swp_entry_t entry)
 			SetPageDirty(page);
 		}
 		unlock_page(page);
-		page_cache_release(page);
+		put_page(page);
 	}
 	return p != NULL;
 }
@@ -1566,7 +1573,7 @@ int try_to_unuse(unsigned int type, bool frontswap,
 		}
 		if (retval) {
 			unlock_page(page);
-			page_cache_release(page);
+			put_page(page);
 			break;
 		}
 
@@ -1618,7 +1625,7 @@ int try_to_unuse(unsigned int type, bool frontswap,
 		 */
 		SetPageDirty(page);
 		unlock_page(page);
-		page_cache_release(page);
+		put_page(page);
 
 		/*
 		 * Make sure that we aren't completely killing
@@ -2580,8 +2587,7 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
 		  (swap_flags & SWAP_FLAG_PRIO_MASK) >> SWAP_FLAG_PRIO_SHIFT;
 	enable_swap_info(p, prio, swap_map, cluster_info, frontswap_map);
 
-	pr_info("Adding %uk swap on %s.  "
-			"Priority:%d extents:%d across:%lluk %s%s%s%s%s\n",
+	pr_info("Adding %uk swap on %s.  Priority:%d extents:%d across:%lluk %s%s%s%s%s\n",
 		p->pages<<(PAGE_SHIFT-10), name->name, p->prio,
 		nr_extents, (unsigned long long)span<<(PAGE_SHIFT-10),
 		(p->flags & SWP_SOLIDSTATE) ? "SS" : "",
@@ -2623,7 +2629,7 @@ bad_swap:
 out:
 	if (page && !IS_ERR(page)) {
 		kunmap(page);
-		page_cache_release(page);
+		put_page(page);
 	}
 	if (name)
 		putname(name);