Messages in this thread Patch in this message | | | From | Jingbo Xu <> | Subject | [PATCH v2 1/2] mm: fix arithmetic for bdi min_ratio | Date | Tue, 19 Dec 2023 10:42:45 +0800 |
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Since now bdi->min_ratio is part per million, fix the wrong arithmetic. Otherwise it will fail with -EINVAL when setting a reasonable min_ratio, as it tries to set min_ratio to (min_ratio * BDI_RATIO_SCALE) in percentage unit, which exceeds 100% anyway.
# cat /sys/class/bdi/253\:0/min_ratio 0 # cat /sys/class/bdi/253\:0/max_ratio 100 # echo 1 > /sys/class/bdi/253\:0/min_ratio -bash: echo: write error: Invalid argument
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 | 1 - 1 file changed, 1 deletion(-)
diff --git a/mm/page-writeback.c b/mm/page-writeback.c index ee2fd6a6af40..2140382dd768 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) { -- 2.19.1.6.gb485710b
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