linux-kernel - [PATCH] swap: do not skip lowest_bit in scan_swap

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Date:	Tue, 21 Jan 2014 18:21:16 -0800
From:	Jamie Liu <jamieliu@...gle.com>
To:	Andrew Morton <akpm@...ux-foundation.org>,
	Shaohua Li <shli@...ionio.com>, Hugh Dickins <hughd@...gle.com>
Cc:	Minchan Kim <minchan@...nel.org>,
	Akinobu Mita <akinobu.mita@...il.com>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, Jamie Liu <jamieliu@...gle.com>
Subject: [PATCH] swap: 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@...gle.com>
---
 mm/swapfile.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/mm/swapfile.c b/mm/swapfile.c
index 612a7c9..6635081 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);
 
-- 
1.8.5.3

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