From 859b81ab005ac2e2673de3d248534206180058d1 Mon Sep 17 00:00:00 2001
From: Oleg Nesterov <oleg@redhat.com>
Date: Sun, 29 Jul 2012 20:22:20 +0200
Subject: [PATCH] --- yaml --- r: 320471 b: refs/heads/master c:
 9f92448ceeea5326db7d114005a7e7ac03904edf h: refs/heads/master i:   320469:
 2ec373569f1286b2105df0dc8e15b711543e0c69   320467:
 eedacddfdfdc891daf143a46d43c45e7460a8a41   320463:
 c6d86850f0387d8bd3eaffbfe285d66d75194536 v: v3

---
 [refs]                        |  2 +-
 trunk/kernel/events/uprobes.c | 27 ++++++++++++++-------------
 2 files changed, 15 insertions(+), 14 deletions(-)

diff --git a/[refs] b/[refs]
index 09f54d933c83..cb2a53fc6dbe 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 089ba999dc881a7549d97c55ac9e0052d061867d
+refs/heads/master: 9f92448ceeea5326db7d114005a7e7ac03904edf
diff --git a/trunk/kernel/events/uprobes.c b/trunk/kernel/events/uprobes.c
index 23c562b7fc2e..5db150b306d2 100644
--- a/trunk/kernel/events/uprobes.c
+++ b/trunk/kernel/events/uprobes.c
@@ -139,10 +139,15 @@ static int __replace_page(struct vm_area_struct *vma, unsigned long addr,
 	struct mm_struct *mm = vma->vm_mm;
 	spinlock_t *ptl;
 	pte_t *ptep;
+	int err;
 
+	/* freeze PageSwapCache() for try_to_free_swap() below */
+	lock_page(page);
+
+	err = -EAGAIN;
 	ptep = page_check_address(page, mm, addr, &ptl, 0);
 	if (!ptep)
-		return -EAGAIN;
+		goto unlock;
 
 	get_page(kpage);
 	page_add_new_anon_rmap(kpage, vma, addr);
@@ -162,7 +167,10 @@ static int __replace_page(struct vm_area_struct *vma, unsigned long addr,
 	put_page(page);
 	pte_unmap_unlock(ptep, ptl);
 
-	return 0;
+	err = 0;
+ unlock:
+	unlock_page(page);
+	return err;
 }
 
 /**
@@ -216,15 +224,10 @@ static int write_opcode(struct arch_uprobe *auprobe, struct mm_struct *mm,
 	ret = -ENOMEM;
 	new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vaddr);
 	if (!new_page)
-		goto put_out;
+		goto put_old;
 
 	__SetPageUptodate(new_page);
 
-	/*
-	 * lock page will serialize against do_wp_page()'s
-	 * PageAnon() handling
-	 */
-	lock_page(old_page);
 	/* copy the page now that we've got it stable */
 	vaddr_old = kmap_atomic(old_page);
 	vaddr_new = kmap_atomic(new_page);
@@ -237,15 +240,13 @@ static int write_opcode(struct arch_uprobe *auprobe, struct mm_struct *mm,
 
 	ret = anon_vma_prepare(vma);
 	if (ret)
-		goto unlock_out;
+		goto put_new;
 
 	ret = __replace_page(vma, vaddr, old_page, new_page);
 
-unlock_out:
-	unlock_page(old_page);
+put_new:
 	page_cache_release(new_page);
-
-put_out:
+put_old:
 	put_page(old_page);
 
 	if (unlikely(ret == -EAGAIN))