From 92bc320bb6d71b37f3336f32c2f97babbcd7df16 Mon Sep 17 00:00:00 2001
From: Cesar Eduardo Barros <cesarb@cesarb.net>
Date: Tue, 11 Dec 2012 16:01:13 -0800
Subject: [PATCH] --- yaml --- r: 338742 b: refs/heads/master c:
 cf0cac0a09341549dedabcfc2a66dcbc2eaaf2b9 h: refs/heads/master v: v3

---
 [refs]              |  2 +-
 trunk/mm/swapfile.c | 26 +++++++++++++++++---------
 2 files changed, 18 insertions(+), 10 deletions(-)

diff --git a/[refs] b/[refs]
index 6251781094eb..e0db3f12dbcf 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: e9868505987a03a26a3979f27b82911ccc003752
+refs/heads/master: cf0cac0a09341549dedabcfc2a66dcbc2eaaf2b9
diff --git a/trunk/mm/swapfile.c b/trunk/mm/swapfile.c
index f91a25547ffe..27a52b731576 100644
--- a/trunk/mm/swapfile.c
+++ b/trunk/mm/swapfile.c
@@ -1443,13 +1443,12 @@ static int setup_swap_extents(struct swap_info_struct *sis, sector_t *span)
 	return generic_swapfile_activate(sis, swap_file, span);
 }
 
-static void enable_swap_info(struct swap_info_struct *p, int prio,
+static void _enable_swap_info(struct swap_info_struct *p, int prio,
 				unsigned char *swap_map,
 				unsigned long *frontswap_map)
 {
 	int i, prev;
 
-	spin_lock(&swap_lock);
 	if (prio >= 0)
 		p->prio = prio;
 	else
@@ -1473,6 +1472,21 @@ static void enable_swap_info(struct swap_info_struct *p, int prio,
 	else
 		swap_info[prev]->next = p->type;
 	frontswap_init(p->type);
+}
+
+static void enable_swap_info(struct swap_info_struct *p, int prio,
+				unsigned char *swap_map,
+				unsigned long *frontswap_map)
+{
+	spin_lock(&swap_lock);
+	_enable_swap_info(p, prio, swap_map, frontswap_map);
+	spin_unlock(&swap_lock);
+}
+
+static void reinsert_swap_info(struct swap_info_struct *p)
+{
+	spin_lock(&swap_lock);
+	_enable_swap_info(p, p->prio, p->swap_map, frontswap_map_get(p));
 	spin_unlock(&swap_lock);
 }
 
@@ -1548,14 +1562,8 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile)
 	compare_swap_oom_score_adj(OOM_SCORE_ADJ_MAX, oom_score_adj);
 
 	if (err) {
-		/*
-		 * reading p->prio and p->swap_map outside the lock is
-		 * safe here because only sys_swapon and sys_swapoff
-		 * change them, and there can be no other sys_swapon or
-		 * sys_swapoff for this swap_info_struct at this point.
-		 */
 		/* re-insert swap space back into swap_list */
-		enable_swap_info(p, p->prio, p->swap_map, frontswap_map_get(p));
+		reinsert_swap_info(p);
 		goto out_dput;
 	}