diff options
| author |   Wen Yang <wenyang@linux.alibaba.com> | 2020-01-13 16:29:26 -0800 |
|---|---|---|
| committer |   Linus Torvalds <torvalds@linux-foundation.org> | 2020-01-13 18:19:02 -0800 |
| commit | d3ac946ec9de10ec4b9718ad30703c5e077916a1 (patch) | |
| tree | 7430f6a5faab50eb94bde53d63b5e20c583caa13 /mm | |
| parent | mm/page-writeback.c: avoid potential division by zero in wb_min_max_ratio() (diff) | |
| download | linux-dev-d3ac946ec9de10ec4b9718ad30703c5e077916a1.tar.xz linux-dev-d3ac946ec9de10ec4b9718ad30703c5e077916a1.zip | |
mm/page-writeback.c: use div64_ul() for u64-by-unsigned-long divide
The two variables 'numerator' and 'denominator', though they are
declared as long, they should actually be unsigned long (according to
the implementation of the fprop_fraction_percpu() function)
And do_div() does a 64-by-32 division, while the divisor 'denominator'
is unsigned long, thus 64-bit on 64-bit platforms. Hence the proper
function to call is div64_ul().
Link: http://lkml.kernel.org/r/20200102081442.8273-3-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>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/page-writeback.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/mm/page-writeback.c b/mm/page-writeback.c index 2d658b208319..c74c6bd6540b 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -766,7 +766,7 @@ static unsigned long __wb_calc_thresh(struct dirty_throttle_control *dtc) struct wb_domain *dom = dtc_dom(dtc); unsigned long thresh = dtc->thresh; u64 wb_thresh; - long numerator, denominator; + unsigned long numerator, denominator; unsigned long wb_min_ratio, wb_max_ratio; /* @@ -777,7 +777,7 @@ static unsigned long __wb_calc_thresh(struct dirty_throttle_control *dtc) wb_thresh = (thresh * (100 - bdi_min_ratio)) / 100; wb_thresh *= numerator; - do_div(wb_thresh, denominator); + wb_thresh = div64_ul(wb_thresh, denominator); wb_min_max_ratio(dtc->wb, &wb_min_ratio, &wb_max_ratio); |