Messages in this thread Patch in this message | | | From | Jingbo Xu <> | Subject | [PATCH] mm: fix arithmetic for bdi min_ratio and max_ratio | Date | Mon, 18 Dec 2023 11:16:40 +0800 |
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bdi->[min|max]_ratio are both part per million. Fix the wrong arithmetic when setting bdi's min_ratio and max_ratio.
Fixes: efc3e6ad53ea ("mm: split off __bdi_set_max_ratio() function") Fixes: 8021fb3232f2 ("mm: split off __bdi_set_min_ratio() function") Reported-by: Joseph Qi <joseph.qi@linux.alibaba.com> Signed-off-by: Jingbo Xu <jefflexu@linux.alibaba.com> --- mm/page-writeback.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/mm/page-writeback.c b/mm/page-writeback.c index ee2fd6a6af40..b393b3281ce9 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -692,7 +692,6 @@ static int __bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ra if (min_ratio > 100 * BDI_RATIO_SCALE) return -EINVAL; - min_ratio *= BDI_RATIO_SCALE; spin_lock_bh(&bdi_lock); if (min_ratio > bdi->max_ratio) { @@ -729,7 +728,8 @@ static int __bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ra ret = -EINVAL; } else { bdi->max_ratio = max_ratio; - bdi->max_prop_frac = (FPROP_FRAC_BASE * max_ratio) / 100; + bdi->max_prop_frac = div64_u64(FPROP_FRAC_BASE * max_ratio, + 100UL * BDI_RATIO_SCALE); } spin_unlock_bh(&bdi_lock); -- 2.19.1.6.gb485710b
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