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authorWen Yang <wenyang@linux.alibaba.com>2020-01-13 16:29:26 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2020-01-13 18:19:02 -0800
commitd3ac946ec9de10ec4b9718ad30703c5e077916a1 (patch)
tree7430f6a5faab50eb94bde53d63b5e20c583caa13 /mm/page-writeback.c
parent6d9e8c651dd979aa666bee15f086745f3ea9c4b3 (diff)
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/page-writeback.c')
-rw-r--r--mm/page-writeback.c4
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);