From 42a7bec9d0907131a905c8fafd105ba8837165dc Mon Sep 17 00:00:00 2001 From: Jingbo Xu Date: Tue, 19 Dec 2023 22:25:07 +0800 Subject: [PATCH 1/2] mm: fix arithmetic for bdi min_ratio ANBZ: #28018 commit e0646b7590084a5bf3b056d3ad871d9379d2c25a upstream. 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 Reported-by: Joseph Qi Cc: Matthew Wilcox (Oracle) Cc: Stefan Roesch Signed-off-by: Andrew Morton Signed-off-by: Jingbo Xu --- mm/page-writeback.c | 1 - 1 file changed, 1 deletion(-) diff --git a/mm/page-writeback.c b/mm/page-writeback.c index 2eeb525665bb..3887cbca2277 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -714,7 +714,6 @@ 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) { -- Gitee From ffa4659996a6f8b06cdda93f0556f29284790c60 Mon Sep 17 00:00:00 2001 From: Jingbo Xu Date: Tue, 19 Dec 2023 22:25:08 +0800 Subject: [PATCH 2/2] mm: fix arithmetic for max_prop_frac when setting max_ratio ANBZ: #28018 commit fa151a39a6879144b587f35c0dfcc15e1be9450f upstream. Since now bdi->max_ratio is part per million, fix the wrong arithmetic for max_prop_frac when setting max_ratio. Otherwise the miscalculated max_prop_frac will affect the incrementing of writeout completion count when max_ratio is not 100%. Link: https://lkml.kernel.org/r/20231219142508.86265-3-jefflexu@linux.alibaba.com Fixes: efc3e6ad53ea ("mm: split off __bdi_set_max_ratio() function") Signed-off-by: Jingbo Xu Cc: Joseph Qi Cc: Matthew Wilcox (Oracle) Cc: Stefan Roesch Signed-off-by: Andrew Morton Signed-off-by: Jingbo Xu --- mm/page-writeback.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/mm/page-writeback.c b/mm/page-writeback.c index 3887cbca2277..0ece77004514 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -750,7 +750,8 @@ 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 = (FPROP_FRAC_BASE * max_ratio) / + (100 * BDI_RATIO_SCALE); } spin_unlock_bh(&bdi_lock); -- Gitee