diff options
| -rw-r--r-- | mm/page-writeback.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/mm/page-writeback.c b/mm/page-writeback.c index b4fd980a93eb..644bcb665773 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c | |||
| @@ -857,8 +857,11 @@ static void bdi_update_write_bandwidth(struct backing_dev_info *bdi, | |||
| 857 | * bw * elapsed + write_bandwidth * (period - elapsed) | 857 | * bw * elapsed + write_bandwidth * (period - elapsed) |
| 858 | * write_bandwidth = --------------------------------------------------- | 858 | * write_bandwidth = --------------------------------------------------- |
| 859 | * period | 859 | * period |
| 860 | * | ||
| 861 | * @written may have decreased due to account_page_redirty(). | ||
| 862 | * Avoid underflowing @bw calculation. | ||
| 860 | */ | 863 | */ |
| 861 | bw = written - bdi->written_stamp; | 864 | bw = written - min(written, bdi->written_stamp); |
| 862 | bw *= HZ; | 865 | bw *= HZ; |
| 863 | if (unlikely(elapsed > period)) { | 866 | if (unlikely(elapsed > period)) { |
| 864 | do_div(bw, elapsed); | 867 | do_div(bw, elapsed); |