From a5998061daab27802c418debe662be98a6e42874 Mon Sep 17 00:00:00 2001
From: Jamie Liu <jamieliu@google.com>
Date: Thu, 23 Jan 2014 15:53:40 -0800
Subject: [PATCH] mm/swapfile.c: do not skip lowest_bit in scan_swap_map() scan
 loop

In the second half of scan_swap_map()'s scan loop, offset is set to
si->lowest_bit and then incremented before entering the loop for the
first time, causing si->swap_map[si->lowest_bit] to be skipped.

Signed-off-by: Jamie Liu <jamieliu@google.com>
Cc: Shaohua Li <shli@fusionio.com>
Acked-by: Hugh Dickins <hughd@google.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 mm/swapfile.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/mm/swapfile.c b/mm/swapfile.c
index d443dea95c27..c6c13b050a58 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -616,7 +616,7 @@ scan:
 		}
 	}
 	offset = si->lowest_bit;
-	while (++offset < scan_base) {
+	while (offset < scan_base) {
 		if (!si->swap_map[offset]) {
 			spin_lock(&si->lock);
 			goto checks;
@@ -629,6 +629,7 @@ scan:
 			cond_resched();
 			latency_ration = LATENCY_LIMIT;
 		}
+		offset++;
 	}
 	spin_lock(&si->lock);
 
-- 
2.20.1