From: Wen Yang <wenyang@xxxxxxxxxxxxxxxxx> 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@xxxxxxxxxxxxxxxxx Signed-off-by: Wen Yang <wenyang@xxxxxxxxxxxxxxxxx> Reviewed-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Cc: Qian Cai <cai@xxxxxx> Cc: Tejun Heo <tj@xxxxxxxxxx> Cc: Jens Axboe <axboe@xxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/page-writeback.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/mm/page-writeback.c~mm-page-writebackc-improve-arithmetic-divisions +++ a/mm/page-writeback.c @@ -1102,7 +1102,7 @@ static void wb_update_write_bandwidth(st 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; } _
