From: Jingbo Xu jefflexu@linux.alibaba.com
mainline inclusion from mainline-v6.7 commit e0646b7590084a5bf3b056d3ad871d9379d2c25a category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IAN96I
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
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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
Link: https://lkml.kernel.org/r/20231219142508.86265-2-jefflexu@linux.alibaba.com Fixes: 8021fb3232f2 ("mm: split off __bdi_set_min_ratio() function") Signed-off-by: Jingbo Xu jefflexu@linux.alibaba.com Reported-by: Joseph Qi joseph.qi@linux.alibaba.com Cc: Matthew Wilcox (Oracle) willy@infradead.org Cc: Stefan Roesch shr@devkernel.io Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Yifan Qiao qiaoyifan4@huawei.com --- mm/page-writeback.c | 1 - 1 file changed, 1 deletion(-)
diff --git a/mm/page-writeback.c b/mm/page-writeback.c index b1c73a9fc3c7..85031998bd58 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -725,7 +725,6 @@ 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) {