Messages in this thread | ![/](/images/icornerl.gif) | | Date | Mon, 18 Dec 2023 11:29:48 +0800 | Subject | Re: [PATCH] mm: fix arithmetic for bdi min_ratio and max_ratio | From | Jingbo Xu <> |
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+cc fsdevel
On 12/18/23 11:16 AM, Jingbo Xu wrote: > 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); >
-- Thanks, Jingbo
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