From a7d9ec70ae39edb3a4e02f6f46ddd619d953e183 Mon Sep 17 00:00:00 2001
From: Michel Lespinasse <walken@google.com>
Date: Thu, 13 Jan 2011 15:46:08 -0800
Subject: [PATCH] --- yaml --- r: 230723 b: refs/heads/master c:
 72ddc8f72270758951ccefb7d190f364d20215ab h: refs/heads/master i:   230721:
 873918def2a6948e2ba8840c436cf872645b3b73   230719:
 fdd8e459da20d4511925317e086a53e4e5537ab8 v: v3

---
 [refs]            |  2 +-
 trunk/mm/memory.c | 72 +++++++++++++++++++++++++----------------------
 2 files changed, 39 insertions(+), 35 deletions(-)

diff --git a/[refs] b/[refs]
index 6b62bd0def9a..b300fca03f45 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: b009c024ff0059e293c1937516f2defe56263650
+refs/heads/master: 72ddc8f72270758951ccefb7d190f364d20215ab
diff --git a/trunk/mm/memory.c b/trunk/mm/memory.c
index d0cc1c134a64..9144fae9a68b 100644
--- a/trunk/mm/memory.c
+++ b/trunk/mm/memory.c
@@ -2229,8 +2229,45 @@ static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
 		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
 		if (ptep_set_access_flags(vma, address, page_table, entry,1))
 			update_mmu_cache(vma, address, page_table);
+		pte_unmap_unlock(page_table, ptl);
 		ret |= VM_FAULT_WRITE;
-		goto unlock;
+
+		if (!dirty_page)
+			return ret;
+
+		/*
+		 * Yes, Virginia, this is actually required to prevent a race
+		 * with clear_page_dirty_for_io() from clearing the page dirty
+		 * bit after it clear all dirty ptes, but before a racing
+		 * do_wp_page installs a dirty pte.
+		 *
+		 * do_no_page is protected similarly.
+		 */
+		if (!page_mkwrite) {
+			wait_on_page_locked(dirty_page);
+			set_page_dirty_balance(dirty_page, page_mkwrite);
+		}
+		put_page(dirty_page);
+		if (page_mkwrite) {
+			struct address_space *mapping = dirty_page->mapping;
+
+			set_page_dirty(dirty_page);
+			unlock_page(dirty_page);
+			page_cache_release(dirty_page);
+			if (mapping)	{
+				/*
+				 * Some device drivers do not set page.mapping
+				 * but still dirty their pages
+				 */
+				balance_dirty_pages_ratelimited(mapping);
+			}
+		}
+
+		/* file_update_time outside page_lock */
+		if (vma->vm_file)
+			file_update_time(vma->vm_file);
+
+		return ret;
 	}
 
 	/*
@@ -2336,39 +2373,6 @@ static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
 		page_cache_release(old_page);
 unlock:
 	pte_unmap_unlock(page_table, ptl);
-	if (dirty_page) {
-		/*
-		 * Yes, Virginia, this is actually required to prevent a race
-		 * with clear_page_dirty_for_io() from clearing the page dirty
-		 * bit after it clear all dirty ptes, but before a racing
-		 * do_wp_page installs a dirty pte.
-		 *
-		 * do_no_page is protected similarly.
-		 */
-		if (!page_mkwrite) {
-			wait_on_page_locked(dirty_page);
-			set_page_dirty_balance(dirty_page, page_mkwrite);
-		}
-		put_page(dirty_page);
-		if (page_mkwrite) {
-			struct address_space *mapping = dirty_page->mapping;
-
-			set_page_dirty(dirty_page);
-			unlock_page(dirty_page);
-			page_cache_release(dirty_page);
-			if (mapping)	{
-				/*
-				 * Some device drivers do not set page.mapping
-				 * but still dirty their pages
-				 */
-				balance_dirty_pages_ratelimited(mapping);
-			}
-		}
-
-		/* file_update_time outside page_lock */
-		if (vma->vm_file)
-			file_update_time(vma->vm_file);
-	}
 	return ret;
 oom_free_new:
 	page_cache_release(new_page);