From 0a5d1a7f64702c351d1f47ef159a0df8c71be0b0 Mon Sep 17 00:00:00 2001
From: Wen Yang <wenyang@linux.alibaba.com>
Date: Mon, 13 Jan 2020 16:29:29 -0800
Subject: mm/page-writeback.c: improve arithmetic divisions

Use div64_ul() instead of do_div() if the divisor is unsigned long, to
avoid truncation to 32-bit on 64-bit platforms.

Link: http://lkml.kernel.org/r/20200102081442.8273-4-wenyang@linux.alibaba.com
Signed-off-by: Wen Yang <wenyang@linux.alibaba.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Qian Cai <cai@lca.pw>
Cc: Tejun Heo <tj@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 mm/page-writeback.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

(limited to 'mm')

diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index c74c6bd6540b..2caf780a42e7 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -1102,7 +1102,7 @@ static void wb_update_write_bandwidth(struct bdi_writeback *wb,
 	bw = written - min(written, wb->written_stamp);
 	bw *= HZ;
 	if (unlikely(elapsed > period)) {
-		do_div(bw, elapsed);
+		bw = div64_ul(bw, elapsed);
 		avg = bw;
 		goto out;
 	}
-- 
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