From 58c37f6e0dfaaab85a3c11fcbf24451dfe70c721 Mon Sep 17 00:00:00 2001 From: KOSAKI Motohiro Date: Mon, 9 Aug 2010 17:19:51 -0700 Subject: [PATCH] vmscan: protect reading of reclaim_stat with lru_lock Rik van Riel pointed out reading reclaim_stat should be protected lru_lock, otherwise vmscan might sweep 2x much pages. This fault was introduced by commit 4f98a2fee8acdb4ac84545df98cccecfd130f8db Author: Rik van Riel Date: Sat Oct 18 20:26:32 2008 -0700 vmscan: split LRU lists into anon & file sets Signed-off-by: KOSAKI Motohiro Cc: Rik van Riel Reviewed-by: Minchan Kim Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/vmscan.c | 20 +++++++++----------- 1 file changed, 9 insertions(+), 11 deletions(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index 1b4e4a5..a3d669f 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -1628,6 +1628,13 @@ static void get_scan_count(struct zone *zone, struct scan_control *sc, } /* + * With swappiness at 100, anonymous and file have the same priority. + * This scanning priority is essentially the inverse of IO cost. + */ + anon_prio = sc->swappiness; + file_prio = 200 - sc->swappiness; + + /* * OK, so we have swap space and a fair amount of page cache * pages. We use the recently rotated / recently scanned * ratios to determine how valuable each cache is. @@ -1638,28 +1645,18 @@ static void get_scan_count(struct zone *zone, struct scan_control *sc, * * anon in [0], file in [1] */ + spin_lock_irq(&zone->lru_lock); if (unlikely(reclaim_stat->recent_scanned[0] > anon / 4)) { - spin_lock_irq(&zone->lru_lock); reclaim_stat->recent_scanned[0] /= 2; reclaim_stat->recent_rotated[0] /= 2; - spin_unlock_irq(&zone->lru_lock); } if (unlikely(reclaim_stat->recent_scanned[1] > file / 4)) { - spin_lock_irq(&zone->lru_lock); reclaim_stat->recent_scanned[1] /= 2; reclaim_stat->recent_rotated[1] /= 2; - spin_unlock_irq(&zone->lru_lock); } /* - * With swappiness at 100, anonymous and file have the same priority. - * This scanning priority is essentially the inverse of IO cost. - */ - anon_prio = sc->swappiness; - file_prio = 200 - sc->swappiness; - - /* * The amount of pressure on anon vs file pages is inversely * proportional to the fraction of recently scanned pages on * each list that were recently referenced and in active use. @@ -1669,6 +1666,7 @@ static void get_scan_count(struct zone *zone, struct scan_control *sc, fp = (file_prio + 1) * (reclaim_stat->recent_scanned[1] + 1); fp /= reclaim_stat->recent_rotated[1] + 1; + spin_unlock_irq(&zone->lru_lock); fraction[0] = ap; fraction[1] = fp; -- 2.7.4