1 files changed, 52 insertions, 25 deletions

diff --git a/mm/swap.c b/mm/swap.c
index 62b78a6e224f..c899502d3e36 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -31,6 +31,7 @@
 #include <linux/memcontrol.h>
 #include <linux/gfp.h>
 #include <linux/uio.h>
+#include <linux/hugetlb.h>
 
 #include "internal.h"
 
@@ -81,6 +82,19 @@ static void __put_compound_page(struct page *page)
 
 static void put_compound_page(struct page *page)
 {
+	/*
+	 * hugetlbfs pages cannot be split from under us.  If this is a
+	 * hugetlbfs page, check refcount on head page and release the page if
+	 * the refcount becomes zero.
+	 */
+	if (PageHuge(page)) {
+		page = compound_head(page);
+		if (put_page_testzero(page))
+			__put_compound_page(page);
+
+		return;
+	}
+
 	if (unlikely(PageTail(page))) {
 		/* __split_huge_page_refcount can run under us */
 		struct page *page_head = compound_trans_head(page);
@@ -184,38 +198,51 @@ bool __get_page_tail(struct page *page)
 	 * proper PT lock that already serializes against
 	 * split_huge_page().
 	 */
-	unsigned long flags;
 	bool got = false;
-	struct page *page_head = compound_trans_head(page);
+	struct page *page_head;
 
-	if (likely(page != page_head && get_page_unless_zero(page_head))) {
+	/*
+	 * If this is a hugetlbfs page it cannot be split under us.  Simply
+	 * increment refcount for the head page.
+	 */
+	if (PageHuge(page)) {
+		page_head = compound_head(page);
+		atomic_inc(&page_head->_count);
+		got = true;
+	} else {
+		unsigned long flags;
+
+		page_head = compound_trans_head(page);
+		if (likely(page != page_head &&
+					get_page_unless_zero(page_head))) {
+
+			/* Ref to put_compound_page() comment. */
+			if (PageSlab(page_head)) {
+				if (likely(PageTail(page))) {
+					__get_page_tail_foll(page, false);
+					return true;
+				} else {
+					put_page(page_head);
+					return false;
+				}
+			}
 
-		/* Ref to put_compound_page() comment. */
-		if (PageSlab(page_head)) {
+			/*
+			 * page_head wasn't a dangling pointer but it
+			 * may not be a head page anymore by the time
+			 * we obtain the lock. That is ok as long as it
+			 * can't be freed from under us.
+			 */
+			flags = compound_lock_irqsave(page_head);
+			/* here __split_huge_page_refcount won't run anymore */
 			if (likely(PageTail(page))) {
 				__get_page_tail_foll(page, false);
-				return true;
-			} else {
-				put_page(page_head);
-				return false;
+				got = true;
 			}
+			compound_unlock_irqrestore(page_head, flags);
+			if (unlikely(!got))
+				put_page(page_head);
 		}
-
-		/*
-		 * page_head wasn't a dangling pointer but it
-		 * may not be a head page anymore by the time
-		 * we obtain the lock. That is ok as long as it
-		 * can't be freed from under us.
-		 */
-		flags = compound_lock_irqsave(page_head);
-		/* here __split_huge_page_refcount won't run anymore */
-		if (likely(PageTail(page))) {
-			__get_page_tail_foll(page, false);
-			got = true;
-		}
-		compound_unlock_irqrestore(page_head, flags);
-		if (unlikely(!got))
-			put_page(page_head);
 	}
 	return got;
 }